From t_ciorba at yahoo.com  Sun Nov  1 03:23:15 2015
From: t_ciorba at yahoo.com (t_ciorba at yahoo.com)
Date: Sun, 1 Nov 2015 10:23:15 +0200
Subject: installer user interface glitch ?
Message-ID: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>

hi,
i am not sure what is wrong, but after launching the installer for windows XPsp3 python-3.5.0.exe i couldnt see what i have to select, it was a white board and the only button on it was "cancel". here is a screen of it: 


when i click on random points of this empty board, i get random stuff, like sending me to "optional features" (where i can finally see what i can choose from), either the installer starts installing it.
-- 
Sent via EmailTray, my personal email concierge.
Get yours at http://www.emailtray.com
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From rosuav at gmail.com  Sun Nov  1 04:43:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 1 Nov 2015 20:43:14 +1100
Subject: Python 2 vs Python 3 for teaching
Message-ID: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>

I'm proud to say that a Python tutoring company has just converted its
course over from teaching Python 2.7 to teaching 3.x. For the
naysayers out there, it actually wasn't much of a transition; putting
parentheses around all print calls, plus changing the way virtual
environments get created, pretty much covered it. The difference
between well-written 2.7 code and well-written 3.4 code is really not
huge.

Interestingly, the bytes/unicode distinction wasn't much of an issue.
Under 2.7, a lot of functions return Unicode strings, and their reprs
show a u prefix, which disappears under Py3. In both cases, a Unicode
string returned from a library will compare equal to a simple
double-quoted string:

>>> import json
>>> json.loads('["Hello", "World"]')
[u'Hello', u'World']
>>> _[0] == "Hello"
True

The bulk of the changes were actually just changing displayed output
to match a change to some object's repr (eg "<type 'bool'>" becomes
"<class 'bool'>", and "set([1])" becomes "{1}"), or the exact text of
an exception (the TypeError from evaluating None[0] looks different,
but it's still a TypeError).

Who out there is currently teaching/tutoring/training using Python 2?
Push to the common subset (parenthesized single string prints, never
assuming int/int yields int, etc), with a view to migration - it's
easier than you might think!

(This isn't meant to be an ad for a specific company, so much as a
general recommendation to push to Py3, but they deserve a bit of a
shout-out anyway. The company is Thinkful, www.thinkful.com.)

ChrisA


From schweiger.gerald at gmail.com  Sun Nov  1 05:04:49 2015
From: schweiger.gerald at gmail.com (gers antifx)
Date: Sun, 1 Nov 2015 02:04:49 -0800 (PST)
Subject: LU decomposition
Message-ID: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>

Hey,

I have to write a LU-decomposition. My Code worked so far but (I want to become better:) ) I want to ask you, if I could write this LU-decomposition in a better way?

def LU(x):
    L = np.eye((x.shape[0]))
    n = x.shape[0]
    for ii in range(n-1): 
        for ll in range(1+ii,n): 
            factor = float(x[ll,ii])/x[ii,ii]  
            L[ll,ii] = factor
            for kk in range(0+ii,n):
                    x[ll,kk] = x[ll,kk] - faktor*x[ii,kk]
    LU = np.dot(L,x)

Thanks


From kwpolska at gmail.com  Sun Nov  1 05:06:36 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Sun, 1 Nov 2015 11:06:36 +0100
Subject: installer user interface glitch ?
In-Reply-To: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
Message-ID: <CAMw+j7J1RFPat6-EnoyRWmxwhOiaXJOGAuKXbL3cVLTw4sT62g@mail.gmail.com>

On 1 November 2015 at 09:23, t_ciorba--- via Python-list
<python-list at python.org> wrote:
>
> hi,
> i am not sure what is wrong, but after launching the installer for windows XPsp3 python-3.5.0.exe i couldnt see what i have to select, it was a white board and the only button on it was "cancel". here is a screen of it:

Windows XP is not supported. Please upgrade to a modern version of
Windows, or switch to Linux. (you could also use 3.4.3, but Windows XP
is insecure, and more apps will follow suit.)

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From rosuav at gmail.com  Sun Nov  1 05:08:47 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 1 Nov 2015 21:08:47 +1100
Subject: installer user interface glitch ?
In-Reply-To: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
Message-ID: <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>

On Sun, Nov 1, 2015 at 7:23 PM, t_ciorba--- via Python-list
<python-list at python.org> wrote:
>
> i am not sure what is wrong, but after launching the installer for windows XPsp3 python-3.5.0.exe i couldnt see what i have to select, it was a white board and the only button on it was "cancel".
>

Yep. The installer isn't very polite at the moment, but when 3.5.1
gets released, it'll be a little clearer in telling you what's going
on - namely, that Python 3.5 does not support Windows XP. You can get
a newer version of Windows (7, 8, 10), or an older version of Python
(3.4), and it should be fine.

Windows XP has now been around for twelve years. It's had its support
run out as many times as Voyager has left the solar system, and if you
really MUST keep using it, one of the costs is going to be that you
also have to use older versions of some software - including Python.
This is going to be increasingly the case. I recommend either
switching to a Unix-based OS (Linux, Mac OS, *BSD, etc) and using Wine
or virtualization to run critical Windows programs, or upgrading to a
newer version of Windows.

ChrisA


From __peter__ at web.de  Sun Nov  1 05:13:51 2015
From: __peter__ at web.de (Peter Otten)
Date: Sun, 01 Nov 2015 11:13:51 +0100
Subject: Puzzled
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
Message-ID: <n14ol2$mfr$1@ger.gmane.org>

Robinson, Wendy wrote:

> Hi there,
> I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic
> programs successfully.
> This morning I rebooted my computer and can't get a single one to work. 
> The interpreter seems to be fine and the environment variables look
> correct.  But every py file I try to run at the >>> prompt gives me a
> NameError.
> 
> I tried running the Repair installation, but that did not help.
> 
> Any suggestions?

If you want to run a python script you have to invoke it on the commandline, 
not inside the interactive interpreter, i. e. if you have a script 
myscript.py containing the line

print("Hello world!")

Wrong:

C:\> python3
>>> myscript.py
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'myscript' is not defined

Here python looks for a variable "myscript" which of course isn't defined. 
(If it were the next step would be to look for an attribute "py" and you'd 
probably get an AttributeError)

Right:

C:\> python3 myscript.py
Hello world!

Here python runs the script and exits.

If you have a function defined in a module that you want to use from the 
interactive interpreter you have to import the module. Assuming mymodule.py
contains the function

def say_hello():
    print("Hello world!")

C:\> python3
>>> import mymodule
>>> mymodule.say_hello()
Hello world!



From rosuav at gmail.com  Sun Nov  1 05:18:37 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 1 Nov 2015 21:18:37 +1100
Subject: LU decomposition
In-Reply-To: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
References: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
Message-ID: <CAPTjJmotPQt4ZhuPetQN5Ft25SVtxON1Xq3LyjQW9D=Fr_CeaQ@mail.gmail.com>

On Sun, Nov 1, 2015 at 9:04 PM, gers antifx <schweiger.gerald at gmail.com> wrote:
> I have to write a LU-decomposition. My Code worked so far but (I want to become better:) ) I want to ask you, if I could write this LU-decomposition in a better way?
>
> def LU(x):
>     L = np.eye((x.shape[0]))
>     n = x.shape[0]
>     for ii in range(n-1):
>         for ll in range(1+ii,n):
>             factor = float(x[ll,ii])/x[ii,ii]
>             L[ll,ii] = factor
>             for kk in range(0+ii,n):
>                     x[ll,kk] = x[ll,kk] - faktor*x[ii,kk]
>     LU = np.dot(L,x)

For a start, I would recommend being careful with your variable names.
You have 'factor' all except one, where you have 'faktor' -
transcription error, or nearly-identical global and local names? And
all your other names are fairly opaque; can they be better named? I'm
particularly looking at this line:

x[ll,kk] = x[ll,kk] - faktor*x[ii,kk]

It is *extremely not obvious* that the first two are using 'll' and
the last one is using 'ii'. (Though I would write this as "x[ll,kk] -=
faktor*x[ii,kk]", which at least cuts down the duplication, so it's
less glitchy to have one out of three that's different.) I was going
to ask if you had some reason for not inverting the factor and simply
using "x[ll,kk] *= factor", till I read it again and saw the
difference.

I'm seeing here a lot of iteration over ranges, then subscripting with
that. Is it possible to iterate over the numpy array itself instead?
That's generally a more Pythonic way to do things.

Assigning to the local name LU at the end of the function seems odd.
Did you intend to return the dot-product?

Beyond that, I'd need a better comprehension of the mathematics behind
this, to evaluate what it's doing. So I'll let the actual experts dive
in :)

ChrisA


From nulla.epistola at web.de  Sun Nov  1 05:19:47 2015
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 1 Nov 2015 11:19:47 +0100
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
Message-ID: <5635E743.9010607@web.de>

Am 30.10.2015 um 17:20 schrieb Robinson, Wendy:
> Hi there,
>
> I installed Python 3.5.0 64-bit for Windows yesterday and tried some
> basic programs successfully.
>
> This morning I rebooted my computer and can?t get a single one to work.
> The interpreter seems to be fine and the environment variables look
> correct.  But every py file I try to run at the >>> prompt gives me a
> NameError.
>

Did you try the exact same things yesterday and this morning? The >>> 
prompt isn't made for running py files, but for directly entering 
statements and executing them. Running py files from a windows command 
prompt (probably after changing into the right directory) should work. 
Importing py files at the >>> prompt and using their content should work 
(again, if Python can find them).

So, what exactly did you do yesterday and what exactly did you do today?

HTH
Sibylle




From nulla.epistola at web.de  Sun Nov  1 05:19:47 2015
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Sun, 1 Nov 2015 11:19:47 +0100
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
Message-ID: <5635E743.9010607@web.de>

Am 30.10.2015 um 17:20 schrieb Robinson, Wendy:
> Hi there,
>
> I installed Python 3.5.0 64-bit for Windows yesterday and tried some
> basic programs successfully.
>
> This morning I rebooted my computer and can?t get a single one to work.
> The interpreter seems to be fine and the environment variables look
> correct.  But every py file I try to run at the >>> prompt gives me a
> NameError.
>

Did you try the exact same things yesterday and this morning? The >>> 
prompt isn't made for running py files, but for directly entering 
statements and executing them. Running py files from a windows command 
prompt (probably after changing into the right directory) should work. 
Importing py files at the >>> prompt and using their content should work 
(again, if Python can find them).

So, what exactly did you do yesterday and what exactly did you do today?

HTH
Sibylle



From lac at openend.se  Sun Nov  1 05:20:34 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 11:20:34 +0100
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
Message-ID: <201511011020.tA1AKYAM004182@fido.openend.se>

In a message of Fri, 30 Oct 2015 09:20:23 -0700, "Robinson, Wendy" writes:
>Hi there,
>I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
>This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.
>
>I tried running the Repair installation, but that did not help.
>
>Any suggestions?
>
>Thank you
>
>Wendy Robinson
>Audit Analyst
>(916) 566-4994 phone

Paste in the Full traceback you get from the console.
Also check and see that the console is actually running the 3.5 you
installed, and not some other python, like 2.7 you might have lying
around.  

Laura


From lac at openend.se  Sun Nov  1 05:24:55 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 11:24:55 +0100
Subject: installer user interface glitch ?
In-Reply-To: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
Message-ID: <201511011024.tA1AOt1a004552@fido.openend.se>

In a message of Sun, 01 Nov 2015 10:23:15 +0200, t_ciorba--- via Python-list wr
ites:
>hi,
>i am not sure what is wrong, but after launching the installer for windows XPsp3 python-3.5.0.exe i couldnt see what i have to select, it was a white board and the only button on it was "cancel". here is a screen of it: 
>
>
>when i click on random points of this empty board, i get random stuff, like sending me to "optional features" (where i can finally see what i can choose from), either the installer starts installing it.
>-- 
>Sent via EmailTray, my personal email concierge.
>Get yours at http://www.emailtray.com

What version of Windows are you running?

If you are on Windows XP, alas, it is not supported and you will need to
get a newer OS.

If you do not know what version you are running, this may help
http://ramblings.timgolden.me.uk/2015/10/08/what-windows-version-am-i-running/

Laura


From lac at openend.se  Sun Nov  1 05:27:25 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 11:27:25 +0100
Subject: installer user interface glitch ?
In-Reply-To: <201511011024.tA1AOt1a004552@fido.openend.se>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <201511011024.tA1AOt1a004552@fido.openend.se>
Message-ID: <201511011027.tA1ARPPM004866@fido.openend.se>

In a message of Sun, 01 Nov 2015 11:24:55 +0100, Laura Creighton writes:
>In a message of Sun, 01 Nov 2015 10:23:15 +0200, t_ciorba--- via Python-list wr
>ites:
>>hi,
>>i am not sure what is wrong, but after launching the installer for windows XPsp3 python-3.5.0.exe i couldnt see what i have to select, it was a white board and the only button on it was "cancel". here is a screen of it: 
>>
>>
>>when i click on random points of this empty board, i get random stuff, like sending me to "optional features" (where i can finally see what i can choose from), either the installer starts installing it.
>>-- 
>>Sent via EmailTray, my personal email concierge.
>>Get yours at http://www.emailtray.com
>
>What version of Windows are you running?
>
>If you are on Windows XP, alas, it is not supported and you will need to
>get a newer OS.
>
>If you do not know what version you are running, this may help
>http://ramblings.timgolden.me.uk/2015/10/08/what-windows-version-am-i-running/
>
>Laura

Ooops, you did say XP, so I just cannot read this morning.  Sorry about
that.  (goes to get more caffeine)

Laura



From __peter__ at web.de  Sun Nov  1 06:55:50 2015
From: __peter__ at web.de (Peter Otten)
Date: Sun, 01 Nov 2015 12:55:50 +0100
Subject: LU decomposition
References: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
Message-ID: <n14uk7$ai0$1@ger.gmane.org>

gers antifx wrote:

> I have to write a LU-decomposition. My Code worked so far but (I want to
> become better:) ) I want to ask you, if I could write this
> LU-decomposition in a better way?
> 
> def LU(x):
>     L = np.eye((x.shape[0]))
>     n = x.shape[0]
>     for ii in range(n-1):
>         for ll in range(1+ii,n):
>             factor = float(x[ll,ii])/x[ii,ii]
>             L[ll,ii] = factor
>             for kk in range(0+ii,n):
>                     x[ll,kk] = x[ll,kk] - faktor*x[ii,kk]
>     LU = np.dot(L,x)

You want to become better? A good way to find the problems Chris pointed out 
quickly is to write unit tests similar to

import unittest
...
from mymodule import LU

class LUTest(unittest.TestCase):
    def test_LU(self):
        matrix = ...
        expected_result = ...
        self.assertEqual(LU(matrix), expected_result)

if __name__ == "__main__":
   unittest.main()

There's no point making stylistic changes or tweaks to improve performance 
on code that doesn't work and doesn't have a well-defined interface yet,
but as a rule of thumb for efficient number-crunching you should try to 
replace for loops with numpy's array operations if at all possible.
Google found me 

http://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.linalg.lu.html

but it's hard to learn from that code as the real meat is a few levels down 
and implemented in C.



From vindhyachal.takniki at gmail.com  Sun Nov  1 09:05:58 2015
From: vindhyachal.takniki at gmail.com (Vindhyachal Takniki)
Date: Sun, 1 Nov 2015 06:05:58 -0800 (PST)
Subject: Multithreading python,two tkinter windows
Message-ID: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>

I have made a python code & using multithreading in it. this is very basic code, not using queues & other stuff.

1. Task is to create two independent Tkinter windows

2. Code has four files: 
main.py:creates individual thread
analog.py: generate random values every 1 sec & 10 sec
screen.py: Tkinter file, screen keeps on updating every 1 sec
scree2.py: Tkinter file, screen keeps on updating every 10 sec

3. My code never run on gives anything. However if in main.py, I disable, one of either screen thread, another screen works fine. i.e they don't work together 


main.py
[code]import thread
import time
import analog
import screen
import screen2

thread.start_new_thread(analog.get_analog_1 , ("Thread-1",))
thread.start_new_thread(analog.get_analog_2 , ("Thread-2",))
thread.start_new_thread(screen.display , ("Thread-3",))
thread.start_new_thread(screen2.display , ("Thread-4",))

while 1:
    pass

[/code]

analog.py
[code]import time
from random import randint


current_time_1 = time.time();
current_time_2 = time.time();
read_ok_1 = 0
read_ok_2 = 0
analog_1 = 0
analog_2 = 0


#get reading at every 1 second
def get_analog_1(thread_name):
    global read_ok_1, current_time_1,analog_1
    while True:
        if((time.time() - current_time_1) > 1):
            if(0 == read_ok_1):
                current_time_1 = time.time();
                read_ok_1 = 1;
                analog_1 = randint(0,100)
                
                
#get reading on update                
def read_update_analog_1():
    global read_ok_1,analog_1
    data1 = 0
    val1 = 0
    if(1 == read_ok_1):
        read_ok_1 = 0;
        data1 = 1;
        val1 = analog_1
        
    return data1,val1                

    
    
#get reading at every 10 second
def get_analog_2(thread_name):
    global read_ok_2, current_time_2,analog_2
    while True:
        if((time.time() - current_time_2) > 10):
            if(0 == read_ok_2):
                current_time_2 = time.time();
                read_ok_2 = 1;
                analog_2 = randint(0,100)
                
                
#get reading on update                
def read_update_analog_2():
    global read_ok_2,analog_2
    data2 = 0
    val2 = 0
    if(1 == read_ok_2):
        read_ok_2 = 0;
        data2 = 1;
        val2 = analog_2
        
    return data2,val2        


[/code]

screen.py
[code]
from Tkinter import *
import analog
import thread
import time

class App():
    
    def __init__(self, master):
        self.master = master

        frame = Frame(master)
        frame.pack()

        label = Label(frame , text = "Analog" , font = ("Helvetica",32))
        label.grid(row = 0)

        self.reading_label = Label(frame, text = '0.0' , font = ("Helvetica",70))
        self.reading_label.grid(row = 1)
        
        self.update_reading()

        

    def update_reading(self):        
        data1,val1 = analog.read_update_analog_1()
        if(1 == data1):
            reading_str = "{:.1f}".format(val1)
            self.reading_label.configure(text = reading_str)
        
        self.master.after(100 , self.update_reading)
        

def display(threadName):
    root = Tk()
    root.wm_title("Ammeter")
    app = App(root)
    root.geometry("480x320")
    root.mainloop()
[/code]

screen2.py
[code]from Tkinter import *
import analog
import thread
import time

class App():
    
    def __init__(self, master):
        self.master = master

        frame = Frame(master)
        frame.pack()

        label = Label(frame , text = "Analog" , font = ("Helvetica",32))
        label.grid(row = 0)

        self.reading_label = Label(frame, text = '0.0' , font = ("Helvetica",70))
        self.reading_label.grid(row = 1)

        self.update_reading()

        

    def update_reading(self):
    
        data1,val1 = analog.read_update_analog_2()
        if(1 == data1):
            reading_str = "{:.1f}".format(val1)
            self.reading_label.configure(text = reading_str)
        
        self.master.after(1000 , self.update_reading)
        

def display(threadName):
    root = Tk()
    root.wm_title("Voltmeter")
    app = App(root)
    root.geometry("480x320")
    root.mainloop()
[/code]


From paul.hermeneutic at gmail.com  Sun Nov  1 09:11:03 2015
From: paul.hermeneutic at gmail.com (paul.hermeneutic at gmail.com)
Date: Sun, 1 Nov 2015 07:11:03 -0700
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
Message-ID: <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>

On Nov 1, 2015 2:45 AM, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> I'm proud to say that a Python tutoring company has just converted its
> course over from teaching Python 2.7 to teaching 3.x. For the
> naysayers out there, it actually wasn't much of a transition;

This would make an excellent opportunity to develop a curriculum to teach
students how to maintain a 2.x and 3.x code base using 2to3.

2.x is not going away as fast as some would like.
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From lac at openend.se  Sun Nov  1 09:26:52 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 15:26:52 +0100
Subject: Multithreading python,two tkinter windows
In-Reply-To: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
References: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
Message-ID: <201511011426.tA1EQqfW022464@fido.openend.se>

In a message of Sun, 01 Nov 2015 06:05:58 -0800, Vindhyachal Takniki writes:
>I have made a python code & using multithreading in it. this is very basic code, not using queues & other stuff.

This is your problem.
The code that uses queues is more basic.
For tkinter you cannot use threads like you do.
You must have one controlling thread, and several worker threads.
The best way to do this is using a queue.

http://code.activestate.com/recipes/82965-threads-tkinter-and-asynchronous-io/

(written by a freind of mine, wandering around in the next room)

outlines how to set this up  for all your tkinter tasks.

Laura




From steve at pearwood.info  Sun Nov  1 09:27:23 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 01:27:23 +1100
Subject: UNABLE TO GET IDLE TO RUN
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
Message-ID: <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>

On Sun, 1 Nov 2015 12:45 pm, Michiel Overtoom wrote:

> 
>> On 31 Oct 2015, at 06:59, Terry Reedy <tjreedy at udel.edu> wrote:
>> This is a different issue than IDLE avoiding clashes.  I opened
>> https://bugs.python.org/issue25522
> 
> Terry, thanks for recording this into the issue tracker.
> 
> I'd go even a step further. I think IDLE should not only warn, but
> completely prevent saving a file which shadows a stdlib module, which will
> effectively render Python unusable.

Really?

[steve at ando ~]$ touch collections.py
[steve at ando ~]$ python -c "import math; print math.sin(1.25)"
0.948984619356

Looks like Python is still usable to me.


> I remember from a few weeks back, a 
> teacher with the same problem posted this on the mailinglist. Eventually
> she had a technician coming in to reinstall Windows, just to fix this
> problem ;-) What an overkill...

If that is true, that's really sad. Were we really unable to tell this
teacher to delete the shadowing file? Or was there more to the problem than
that?



-- 
Steven



From rosuav at gmail.com  Sun Nov  1 09:27:24 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 01:27:24 +1100
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
Message-ID: <CAPTjJmo+st5-iUZ0Fie7EZ7YnGjWioTpLDqFdOm359g521YwhQ@mail.gmail.com>

On Mon, Nov 2, 2015 at 1:11 AM,  <paul.hermeneutic at gmail.com> wrote:
> On Nov 1, 2015 2:45 AM, "Chris Angelico" <rosuav at gmail.com> wrote:
>>
>> I'm proud to say that a Python tutoring company has just converted its
>> course over from teaching Python 2.7 to teaching 3.x. For the
>> naysayers out there, it actually wasn't much of a transition;
>
> This would make an excellent opportunity to develop a curriculum to teach
> students how to maintain a 2.x and 3.x code base using 2to3.
>
> 2.x is not going away as fast as some would like.

I'd rather not use 2to3 there. If you want to maintain a library that
can be used from 2.x and 3.x, it's much better to aim for the
compatible middle - u prefixes on all Unicode strings, b prefixes on
all byte strings, stick to ASCII where possible, etc, etc. Much easier
than writing code for one branch and then converting to the other.

We do have a few mentions in the course of "here's how Python 2 is
different", but we're not teaching people to write libraries, so the
notion of one program that can be run on multiple branches of Python
isn't all that significant. If you're going to maintain a 2.x
codebase, there's no knowing what kinds of coding styles it'll use -
you can't depend on it being written for 2.7 - which makes it nearly
impossible to try to teach in a generic way. The task of supporting a
legacy codebase is always one of "learn the language, then learn the
codebase"; why bother teaching things like "except ValueError, e:" or
(worse) the old style of string exceptions, just in case someone runs
into them somewhere? No. We teach 3.4 (because that's what's available
on the Ubuntu VMs that we're recommending; anything 3.2+ will probably
work just the same), and that's it.

ChrisA


From rosuav at gmail.com  Sun Nov  1 09:31:35 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 01:31:35 +1100
Subject: Multithreading python,two tkinter windows
In-Reply-To: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
References: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
Message-ID: <CAPTjJmrh8uY-7cCF3jxTnKk=Gh-sqWSCvt4k+AHjo7rhFU0EDQ@mail.gmail.com>

On Mon, Nov 2, 2015 at 1:05 AM, Vindhyachal Takniki
<vindhyachal.takniki at gmail.com> wrote:
> #get reading at every 1 second
> def get_analog_1(thread_name):
>     global read_ok_1, current_time_1,analog_1
>     while True:
>         if((time.time() - current_time_1) > 1):
>             if(0 == read_ok_1):
>                 current_time_1 = time.time();
>                 read_ok_1 = 1;
>                 analog_1 = randint(0,100)

Never do this. It's called a "busy-wait", and not only does it
saturate your Python thread, it also saturates your entire system -
this is going to keep one CPU core permanently busy going "are we
there yet? are we there yet?" about the one-second delay. Instead, use
time.sleep(), which will delay your thread by one second, allowing
other threads to run.

Better still, think about your code in terms of events. Most GUI
libraries these days are built around an event-driven model, and the
notion of "make this event happen 1 second from now" or "10 seconds
from now" is a very common one.

ChrisA


From steve at pearwood.info  Sun Nov  1 09:41:10 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 01:41:10 +1100
Subject: UNABLE TO GET IDLE TO RUN
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org> <A8FC743A-822E-438E-A3CA-F27C5D3EE392@xs4all.nl>
 <mailman.5.1446346235.4463.python-list@python.org>
Message-ID: <56362487$0$1611$c3e8da3$5496439d@news.astraweb.com>

On Sun, 1 Nov 2015 01:50 pm, Terry Reedy wrote:

> On 10/31/2015 9:45 PM, Michiel Overtoom wrote:

>> I'd go even a step further. I think IDLE should not only warn, but
> 
> The warning will require a choice, with the default (if one just hits
> <Enter>) being to reject the duplicate and go back to the Save-as
> dialog.  Please add yourself as nosy on the issue so you can comment on
> the message whenever I get around to adding a patch.


Users are inclined to ignore alerts, dialogs and error messages, and
applications try very, very hard to reinforce that tendency.

http://ux.stackexchange.com/questions/4518/should-alert-boxes-be-avoided-at-any-cost

Good to see that IDLE is going to continue that fine old tradition of
degrading usability for the sake of a quick and easy non-solution to a
problem.

:-(


-- 
Steven



From lac at openend.se  Sun Nov  1 09:49:37 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 15:49:37 +0100
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <CAPTjJmo+st5-iUZ0Fie7EZ7YnGjWioTpLDqFdOm359g521YwhQ@mail.gmail.com>
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
 <CAPTjJmo+st5-iUZ0Fie7EZ7YnGjWioTpLDqFdOm359g521YwhQ@mail.gmail.com>
Message-ID: <201511011449.tA1Enbbp024177@fido.openend.se>

In a message of Mon, 02 Nov 2015 01:27:24 +1100, Chris Angelico writes:
>On Mon, Nov 2, 2015 at 1:11 AM,  <paul.hermeneutic at gmail.com> wrote:
>> On Nov 1, 2015 2:45 AM, "Chris Angelico" <rosuav at gmail.com> wrote:
>>>
>>> I'm proud to say that a Python tutoring company has just converted its
>>> course over from teaching Python 2.7 to teaching 3.x. For the
>>> naysayers out there, it actually wasn't much of a transition;
>>
>> This would make an excellent opportunity to develop a curriculum to teach
>> students how to maintain a 2.x and 3.x code base using 2to3.
>>
>> 2.x is not going away as fast as some would like.

>I'd rather not use 2to3 there. If you want to maintain a library that
>can be used from 2.x and 3.x, it's much better to aim for the
>compatible middle - u prefixes on all Unicode strings, b prefixes on
>all byte strings, stick to ASCII where possible, etc, etc. Much easier
>than writing code for one branch and then converting to the other.

How about using six, same idea with the curriculum?

Laura


From rosuav at gmail.com  Sun Nov  1 09:52:43 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 01:52:43 +1100
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <201511011449.tA1Enbbp024177@fido.openend.se>
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
 <CAPTjJmo+st5-iUZ0Fie7EZ7YnGjWioTpLDqFdOm359g521YwhQ@mail.gmail.com>
 <201511011449.tA1Enbbp024177@fido.openend.se>
Message-ID: <CAPTjJmrhDY2CwVPpL+KjMXxx-TSk30Orvp6aJz1LJwfosOUcJw@mail.gmail.com>

On Mon, Nov 2, 2015 at 1:49 AM, Laura Creighton <lac at openend.se> wrote:
>>I'd rather not use 2to3 there. If you want to maintain a library that
>>can be used from 2.x and 3.x, it's much better to aim for the
>>compatible middle - u prefixes on all Unicode strings, b prefixes on
>>all byte strings, stick to ASCII where possible, etc, etc. Much easier
>>than writing code for one branch and then converting to the other.
>
> How about using six, same idea with the curriculum?

If we were building libraries, then yes, six would be the way to go.
But there's really no reason to bother - we're building applications
from scratch (or from templates that are under our control), so it's
easy to stipulate that Python 3.x is a prerequisite.

ChrisA


From mail at timgolden.me.uk  Sun Nov  1 10:01:00 2015
From: mail at timgolden.me.uk (Tim Golden)
Date: Sun, 1 Nov 2015 15:01:00 +0000
Subject: UNABLE TO GET IDLE TO RUN
In-Reply-To: <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5636292C.6090603@timgolden.me.uk>

On 01/11/2015 14:27, Steven D'Aprano wrote:
>> I remember from a few weeks back, a
>> teacher with the same problem posted this on the mailinglist. Eventually
>> she had a technician coming in to reinstall Windows, just to fix this
>> problem ;-) What an overkill...
>
> If that is true, that's really sad. Were we really unable to tell this
> teacher to delete the shadowing file? Or was there more to the problem than
> that?

We tried, over the course of several days. It looked like a simple 
"delete this and try again" problem. After a couple of iterations she 
and her tech support obviously decided that re-imaging the lab machines 
was a better use of their time to achieve their goal (get the thing 
working) than further distance-learning diagnostics.

TJG


From rurpy at yahoo.com  Sun Nov  1 10:43:34 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Sun, 1 Nov 2015 07:43:34 -0800 (PST)
Subject: installer user interface glitch ?
In-Reply-To: <mailman.11.1446372398.4463.python-list@python.org>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
Message-ID: <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>

On 11/01/2015 03:06 AM, Chris Warrick wrote:
> On 1 November 2015 at 09:23, t_ciorba--- via Python-list 
> <python-list at python.org> wrote:
>> 
>> hi, i am not sure what is wrong, but after launching the installer
>> for windows XPsp3 python-3.5.0.exe i couldnt see what i have to
>> select, it was a white board and the only button on it was
>> "cancel". here is a screen of it:
> 
> Windows XP is not supported. Please upgrade to a modern version of 
> Windows, or switch to Linux. (you could also use 3.4.3, but Windows
> XP is insecure, and more apps will follow suit.)

Why, oh why, do the python.org front page and other pages that offer
a Windows download not say a word about it not running on Windows XP?

Even if one is anal enough to go to the page about the 3.5 release.
  https://www.python.org/downloads/release/python-350/
a page with a lot of Windows-specific info, there is not a word
about XP.

Or perhaps the number of posts to this list are declining and having
people download Python-3.5, have it fail, and then ask why here is
part of a secret plan to increase list volume?


From rosuav at gmail.com  Sun Nov  1 10:52:27 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 02:52:27 +1100
Subject: installer user interface glitch ?
In-Reply-To: <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
Message-ID: <CAPTjJmosPAZcBSZG6G1BDxZ_j+SU70=Sj0vNeCe2z=DfEiJD3w@mail.gmail.com>

On Mon, Nov 2, 2015 at 2:43 AM, rurpy--- via Python-list
<python-list at python.org> wrote:
> Why, oh why, do the python.org front page and other pages that offer
> a Windows download not say a word about it not running on Windows XP?
>
> Even if one is anal enough to go to the page about the 3.5 release.
>   https://www.python.org/downloads/release/python-350/
> a page with a lot of Windows-specific info, there is not a word
> about XP.

A partial answer to that is in PEP 11:

https://www.python.org/dev/peps/pep-0011/#microsoft-windows

Windows XP isn't special here. There's no mention of Python 2.7 not
working on Windows 95, because it's simply an unsupported operating
system. The only reason that people keep coming asking about XP and
not (say) Win2K is that there are a lot more XP boxes out there. Do
the other download pages need to stipulate which versions of which
OSes they support, or should that be left up to the installer?

There *is* a plan to have the installer give a better error message
for this situation. But I don't think the web site necessarily has to
have noise about old versions of OSes. Where would you draw the line?

ChrisA


From motoom at xs4all.nl  Sun Nov  1 10:54:45 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Sun, 1 Nov 2015 16:54:45 +0100
Subject: installer user interface glitch ?
In-Reply-To: <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
Message-ID: <A8BF5D25-7072-44F1-A4D5-680B0DA7EE65@xs4all.nl>


> On 01 Nov 2015, at 16:43, rurpy--- via Python-list <python-list at python.org> wrote:
> 
> Why, oh why, do the python.org front page and other pages that offer
> a Windows download not say a word about it not running on Windows XP?

I'm also curious why Python 3.5 won't run on Windows XP. Which features does it use that require Windows 7 or higher? Or is the decision to not support Windows XP based on Microsoft ending the product support lifecycle for XP?

Greetings,



From lac at openend.se  Sun Nov  1 11:17:31 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 17:17:31 +0100
Subject: UNABLE TO GET IDLE TO RUN
In-Reply-To: <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <201511011617.tA1GHVKE030820@fido.openend.se>

I managed to delete the real mail I would like to reply to.
This is, at least in the same thread ....

In a message of Mon, 02 Nov 2015 01:27:23 +1100, "Steven D'Aprano" writes
a reply to Michael Overtoon:

> Users are inclined to ignore alerts, dialogs and error messages, and
> applications try very, very hard to reinforce that tendency.

http://ux.stackexchange.com/questions/4518/should-alert-boxes-be-avoided-at-any-cost

(ok posting of question.)

> Good to see that IDLE is going to continue that fine old tradition of
> degrading usability for the sake of a quick and easy non-solution to a
> problem.

I think you owe Michael an apology.
Winning an argument on  'I should I get it my way because I can come up with
a pithy and condescending way to phrase my objection to what you
want to do' seems morally bankrupt to me.  Ditto on the idea of bashing
him just because he is handy and the world is a bad place for you right 
now.  It hardly counts as a technical reason for or against the issuing
of warnings in idle, or the more severe 'not allowing you to save'.

I have a professional carreer based on saying 'do not blather useless
error/warning messages' at people.  I am pretty much always on your
side of the argument.  But, here we are, first time in 22 years, and
I am here arguing in _favour_ of a warning message. :)

I very much want to convince Michael that my warning will be sufficient,
thus preventing people from writing out strings.py is unnecessary.
It's going to be damn hard to do so if he is stung by your 
non-constructive (however brilliant) remark.

Laura


From rurpy at yahoo.com  Sun Nov  1 11:24:22 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Sun, 1 Nov 2015 08:24:22 -0800 (PST)
Subject: installer user interface glitch ?
In-Reply-To: <mailman.27.1446393155.4463.python-list@python.org>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
Message-ID: <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>

On Sunday, November 1, 2015 at 8:52:55 AM UTC-7, Chris Angelico wrote:
> On Mon, Nov 2, 2015 at 2:43 AM, rurpy--- via Python-list <python-list at python.org> wrote:
> > Why, oh why, do the python.org front page and other pages that offer
> > a Windows download not say a word about it not running on Windows XP?
> >
> > Even if one is anal enough to go to the page about the 3.5 release.
> >   https://www.python.org/downloads/release/python-350/
> > a page with a lot of Windows-specific info, there is not a word
> > about XP.
> 
> A partial answer to that is in PEP 11:
> 
> https://www.python.org/dev/peps/pep-0011/#microsoft-windows
> 
> Windows XP isn't special here. There's no mention of Python 2.7 not
> working on Windows 95, because it's simply an unsupported operating
> system. The only reason that people keep coming asking about XP and
> not (say) Win2K is that there are a lot more XP boxes out there. Do
> the other download pages need to stipulate which versions of which
> OSes they support, or should that be left up to the installer?

I dont recall seeing anyone posting asking why they could not get 
Python to install on Windows 95 recently.  I only read this group
intermittently but I have seen *many* posts asking why they couldnt
install on XP.

You acknowledge yourself: "there are a lot more XP boxes out there."

> There *is* a plan to have the installer give a better error message
> for this situation.

A better message from the installer is necessary but not sufficient.
Don't make people go through the effort to download the whole thing,
do their planning and preparations for using or upgrading Python 
only to discover at the last moment it wont work.

That is really shitty customer relations.

The reality is that people trying install Python-3.5 on XP *is* a 
problem.  Telling them they should have read some obscure release 
notes is not a solution.

> But I don't think the web site necessarily has to
> have noise about old versions of OSes. Where would you draw the line?

I think my responses above answer that.


From torriem at gmail.com  Sun Nov  1 11:39:00 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 01 Nov 2015 09:39:00 -0700
Subject: installer user interface glitch ?
In-Reply-To: <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
Message-ID: <56364024.10707@gmail.com>

On 11/01/2015 03:08 AM, Chris Angelico wrote:
> Windows XP has now been around for twelve years. 

It's older than that.  Release date was August 1, 2001.  More than 14
years ago.  My how the time flies.

Though more recent versions of Windows have added features (which Python
now takes advantage of), it doesn't seem to me that we've gained much in
all that time in overall usability terms, from an end-user persepective.
 If it weren't for security issues, I'm sure Windows XP would work just
fine indefinitely for some tasks.  But they will have to stick with
unmaintained software and any problems that entails.


From rosuav at gmail.com  Sun Nov  1 11:43:28 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 03:43:28 +1100
Subject: installer user interface glitch ?
In-Reply-To: <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
Message-ID: <CAPTjJmqNzip8oKQ_wy-kG8DXFQnLgqdkVrZ6xy=rD9MZe1EroA@mail.gmail.com>

On Mon, Nov 2, 2015 at 3:24 AM, rurpy--- via Python-list
<python-list at python.org> wrote:
> I dont recall seeing anyone posting asking why they could not get
> Python to install on Windows 95 recently.  I only read this group
> intermittently but I have seen *many* posts asking why they couldnt
> install on XP.
>
> You acknowledge yourself: "there are a lot more XP boxes out there."

Yes, there are. This is not a customer base; they are not paying me,
nor (as far as I know) the PSF, to support them.

>> There *is* a plan to have the installer give a better error message
>> for this situation.
>
> A better message from the installer is necessary but not sufficient.
> Don't make people go through the effort to download the whole thing,
> do their planning and preparations for using or upgrading Python
> only to discover at the last moment it wont work.

The largest installer [1] is 30MB, which might have been considered
large a decade ago, but on today's connections, that's probably going
to download in less time than it takes people to search for "python",
find python.org, and decide to click the download link. The web
installer is less than one megabyte. If you can't afford to download a
single meg of executable to find out whether something works on your
system, you probably can't afford to download the page with the info
telling you not to bother downloading the binary.

> That is really shitty customer relations.

See above, and define 'customer'.

> The reality is that people trying install Python-3.5 on XP *is* a
> problem.  Telling them they should have read some obscure release
> notes is not a solution.

Nor is telling them they should have read the web site that they
downloaded it from. Remember, people can click a direct download link
*on the python.org front page* and be immediately downloading Python 2
or 3 for the OS that the browser announces. Where would you put the
big fat noisy warning?

>> But I don't think the web site necessarily has to
>> have noise about old versions of OSes. Where would you draw the line?
>
> I think my responses above answer that.

Not really, no. There are currently a large number of XP boxes out
there, for some definition of 'large'. Presumably that number is
dropping. At what point will it be appropriate to ditch the warning?
And what about older versions of non-Windows OSes - if there are a
large number of people still running an old Mac OS, should we include
something on the front page that warns everyone about a lack of
support? How large is large? I say again: Where would you draw the
line?

ChrisA

[1] Based on the file sizes here:
https://www.python.org/downloads/release/python-350/


From rosuav at gmail.com  Sun Nov  1 12:01:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 04:01:41 +1100
Subject: installer user interface glitch ?
In-Reply-To: <56364024.10707@gmail.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
 <56364024.10707@gmail.com>
Message-ID: <CAPTjJmpAFgDfOXNXoFpaP1Dc5rGHKJJ6w1U4x5irbqAh6KLHWA@mail.gmail.com>

On Mon, Nov 2, 2015 at 3:39 AM, Michael Torrie <torriem at gmail.com> wrote:
> On 11/01/2015 03:08 AM, Chris Angelico wrote:
>> Windows XP has now been around for twelve years.
>
> It's older than that.  Release date was August 1, 2001.  More than 14
> years ago.  My how the time flies.
>
> Though more recent versions of Windows have added features (which Python
> now takes advantage of), it doesn't seem to me that we've gained much in
> all that time in overall usability terms, from an end-user persepective.
>  If it weren't for security issues, I'm sure Windows XP would work just
> fine indefinitely for some tasks.  But they will have to stick with
> unmaintained software and any problems that entails.

Hmm. I had a mental notion of XP as a 2003 release. So, it's even more
so: it's been around for fourteen years, and XPSP3 came out seven
years ago, so it's been that long since a major upgrade of any sort.
That's approximately the age of RHEL 5 - and a base XP is slightly
older than RHEL 2.1, the oldest that I can find dates for. If we're
really generous, then, we can accept that XP SP3 is about on par with
a Linux that's shipping Python 2.4. The fact that 2.7 and 3.4 both run
on XP is a tribute to the extensive support that XP *does* have.

ChrisA


From lac at openend.se  Sun Nov  1 12:25:21 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 18:25:21 +0100
Subject: installer user interface glitch ?
In-Reply-To: <CAPTjJmpAFgDfOXNXoFpaP1Dc5rGHKJJ6w1U4x5irbqAh6KLHWA@mail.gmail.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
 <56364024.10707@gmail.com>
 <CAPTjJmpAFgDfOXNXoFpaP1Dc5rGHKJJ6w1U4x5irbqAh6KLHWA@mail.gmail.com>
Message-ID: <201511011725.tA1HPL1S003700@fido.openend.se>

The important thing is that, numbers-wise, windowsXP was the
version of computer a whole lot of people got when they got
their first computer.

The notion of, not it "wearing out" but that the whole world
"wore out" or "advanced  beyond" them is foreign to them.

They aren't computer-hobbyists -- they are early adopters of
the web browser and internet search, if anything.

The whole message of 'get a newer os' is decidedly hard for them.
"It works fine, like my 2004 Ford car" they want to tell you.

Laura



From invalid at invalid.invalid  Sun Nov  1 12:56:33 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Sun, 1 Nov 2015 17:56:33 +0000 (UTC)
Subject: installer user interface glitch ?
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
 <56364024.10707@gmail.com>
 <CAPTjJmpAFgDfOXNXoFpaP1Dc5rGHKJJ6w1U4x5irbqAh6KLHWA@mail.gmail.com>
 <mailman.33.1446398729.4463.python-list@python.org>
Message-ID: <n15joh$k08$1@reader1.panix.com>

On 2015-11-01, Laura Creighton <lac at openend.se> wrote:

> The whole message of 'get a newer os' is decidedly hard for them.
> "It works fine, like my 2004 Ford car" they want to tell you.

Except it _doesn't_ work fine, or they wouldn't be complaining.

If you want to run Python 3.5, then XP just doesn't work.  Why they
think it's Python's fault is the question...

--
Grant




From lac at openend.se  Sun Nov  1 13:08:40 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 19:08:40 +0100
Subject: installer user interface glitch ?
In-Reply-To: <n15joh$k08$1@reader1.panix.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <CAPTjJmpN=ZdDMN26m7WAM5DyqoftSy=tGDW-G458c6YBr9Y19A@mail.gmail.com>
 <56364024.10707@gmail.com>
 <CAPTjJmpAFgDfOXNXoFpaP1Dc5rGHKJJ6w1U4x5irbqAh6KLHWA@mail.gmail.com>
 <mailman.33.1446398729.4463.python-list@python.org>
 <n15joh$k08$1@reader1.panix.com>
Message-ID: <201511011808.tA1I8eSt006945@fido.openend.se>

In a message of Sun, 01 Nov 2015 17:56:33 +0000, Grant Edwards writes:
>On 2015-11-01, Laura Creighton <lac at openend.se> wrote:
>
>> The whole message of 'get a newer os' is decidedly hard for them.
>> "It works fine, like my 2004 Ford car" they want to tell you.
>
>Except it _doesn't_ work fine, or they wouldn't be complaining.
>
>If you want to run Python 3.5, then XP just doesn't work.  Why they
>think it's Python's fault is the question...
>
>--
>Grant

:)

Actually, the people I talk to are to be forgiven for not understanding
that 3.5 does not work for them given that the installer does not
spit them out with a fail message at the start.

It's the next step.

"Why can you not make a product for my perfectly working system!"

that I was thinking about.

And, to be fair, lots of them are grandparents who want to be able to
see their grandchildren's turtle programs ....

Not the usual case for 'need to download python', to be sure

Laura



From rurpy at yahoo.com  Sun Nov  1 14:41:42 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Sun, 1 Nov 2015 11:41:42 -0800 (PST)
Subject: installer user interface glitch ?
In-Reply-To: <mailman.31.1446396218.4463.python-list@python.org>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
Message-ID: <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>

On 11/01/2015 09:43 AM, Chris Angelico wrote:
> On Mon, Nov 2, 2015 at 3:24 AM, rurpy--- via Python-list <python-list at python.org> wrote:
>> I dont recall seeing anyone posting asking why they could not get
>> Python to install on Windows 95 recently.  I only read this group
>> intermittently but I have seen *many* posts asking why they couldnt
>> install on XP.
>>
>> You acknowledge yourself: "there are a lot more XP boxes out there."
> 
> Yes, there are. This is not a customer base; they are not paying me,
> nor (as far as I know) the PSF, to support them.

I wasn't asking *you* to do anything. And I wasn't asking for python
to support XP. I'm not sure how you have possibly got that idea.
In fact I wasn't *asking* anyone to do anything.

I was pointing out (the obvious) that there was a problem with people
not understanding that Python-3.5 will not run on XP and suggesting a
low-cost way to reduce that problem.

>>> There *is* a plan to have the installer give a better error message
>>> for this situation.
>>
>> A better message from the installer is necessary but not sufficient.
>> Don't make people go through the effort to download the whole thing,
>> do their planning and preparations for using or upgrading Python
>> only to discover at the last moment it wont work.
> 
> The largest installer [1] is 30MB, which might have been considered
> large a decade ago, but on today's connections, that's probably going
> to download in less time than it takes people to search for "python",
> find python.org, and decide to click the download link. The web
> installer is less than one megabyte. If you can't afford to download a
> single meg of executable to find out whether something works on your
> system, you probably can't afford to download the page with the info
> telling you not to bother downloading the binary.

As I said it is not solely the number of minutes needed to download
something.

And not everyone in the world has high-speed reliable connection.
It wasn't that long ago my internet connection was a modem. And
even today with screaming fast 100KB/s (sometimes) connection I often
have to babysit a download to get it to complete or deal with long
outages. There are plenty of places much less connected than I am.
And of course those are the same places where people are more likely
to still be using XP.

>> That is really shitty customer relations.
> 
> See above, and define 'customer'.

customer: the people to whom you are providing a product or service.

Of course, unless the PSF has a charter that imposes some legal
requirements, PSF/Python development community has no legal
obligation to do anything for anyone. They could add spam-ware
to the installer, make backward incompatible changes on a whim,
release software that crashes when started.

Now could we return to reality please?

>> The reality is that people trying install Python-3.5 on XP *is* a
>> problem.  Telling them they should have read some obscure release
>> notes is not a solution.
> 
> Nor is telling them they should have read the web site that they
> downloaded it from. Remember, people can click a direct download link
> *on the python.org front page* and be immediately downloading Python 2
> or 3 for the OS that the browser announces. 

Where is that? I didn't see anything that wasn't accompanied with text
that could accommodate a windows xp warning. But then I was looking
at it from a Linux machine. And even if it is impossibly awkward to
provide in one case (though I doubt that's the case), there certainly
should be a warning on the windows specific pages.

AFAIK, the only place where dropping XP support is mentioned in the
docs is way down the bottom of What's New. PEP-11 doesn't count --
it unrealistic in the extreme to expect a Windows user who wants to
try Python to read (or even know about) the PEPs, or that one of
them describes supported OSes.

> Where would you put the
> big fat noisy warning?

I would not put a "big fat noisy warning" anywhere. I would put a
minimally sized but clear notice where the windows version of python-3.5
can be downloaded.
 
>>> But I don't think the web site necessarily has to
>>> have noise about old versions of OSes. Where would you draw the line?

What noise? Providing basic useful information to a significant
number of customers/clients/users, information that is not provided
elsewhere in the normal course of their actions, is not "noise".

If you want to get rid of noise, how about ditching corporate-style
PR like "Success Stories", or a big graphic of fibonacci numbers in
python?

It's really sad to see open source projects taken over by marketing
wanna-bees who think PR fluff is more important that actual actionable
information.

>> I think my responses above answer that.
> 
> Not really, no. There are currently a large number of XP boxes out
> there, for some definition of 'large'. Presumably that number is
> dropping. At what point will it be appropriate to ditch the warning?
> And what about older versions of non-Windows OSes - if there are a
> large number of people still running an old Mac OS, should we include
> something on the front page that warns everyone about a lack of
> support? 

Why don't you try answering that question yourself? Start by asking
how many posts to this list asking why the poster couldn't install
Python-3.5 on an old MacOS system you've seen.

> How large is large? I say again: Where would you draw the
> line?

If you insist on a concrete number (I presume so you can pick nits
with it rather than the general proposition), 5 years. Then reevaluate.
Once someone has actually adds a note dispute about whether it should
be there will fade into nothingness and removing it after xp truly
is insignificant will be contentious.


From no.email at nospam.invalid  Sun Nov  1 14:47:37 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Sun, 01 Nov 2015 11:47:37 -0800
Subject: Python 2 vs Python 3 for teaching
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
 <mailman.22.1446388053.4463.python-list@python.org>
Message-ID: <87y4ehzeli.fsf@nightsong.com>

Chris Angelico <rosuav at gmail.com> writes:
> We teach 3.4 (because that's what's available on the Ubuntu VMs that
> we're recommending; anything 3.2+ will probably work just the same),
> and that's it.

The async keyword seems like one of Py3's bigger improvements and it
makes its appearance in 3.5, iirc.


From python at mrabarnett.plus.com  Sun Nov  1 15:46:18 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 1 Nov 2015 20:46:18 +0000
Subject: installer user interface glitch ?
In-Reply-To: <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
Message-ID: <56367A1A.7020007@mrabarnett.plus.com>

On 2015-11-01 19:41, rurpy--- via Python-list wrote:
> On 11/01/2015 09:43 AM, Chris Angelico wrote:
>> On Mon, Nov 2, 2015 at 3:24 AM, rurpy--- via Python-list <python-list at python.org> wrote:
[snip]
>>> That is really shitty customer relations.
>>
>> See above, and define 'customer'.
>
> customer: the people to whom you are providing a product or service.
>
A customer is someone who receives goods or services in return for some
kind of monetary or other payment.

The PSF makes Python available as-is, gratis.

Those who are downloading Python from the PSF are not "customers".

[snip]



From luisjosenovoa at gmail.com  Sun Nov  1 16:27:27 2015
From: luisjosenovoa at gmail.com (LJ)
Date: Sun, 1 Nov 2015 13:27:27 -0800 (PST)
Subject: PyPy subprocess
Message-ID: <37cd1025-2b18-48bf-a3cc-e792cce11b58@googlegroups.com>

Hi All.

I hope you're having a good weekend. Im working on a large scale optimization problem which invokes the Gurobi solver from python. Before invoking the solver I use pure python to solve five subproblems in parallel using the multiprocessing module. These subproblems are the bottleneck of my procedure. Im wondering if there is a way in which I can use PyPy to solve the just subproblems in parallel, and return to CPython for the overall routines. The reason behind this, is that Gurobipy (python interface for the Gurobi optimization solver) is not compatible with PyPy, and Im seeing savings of 50% in time when using PyPy to somve the subproblems.

Any help would be highly appreciated.

Lj.


From luisjosenovoa at gmail.com  Sun Nov  1 16:29:01 2015
From: luisjosenovoa at gmail.com (LJ)
Date: Sun, 1 Nov 2015 13:29:01 -0800 (PST)
Subject: PyPy subprocess
In-Reply-To: <37cd1025-2b18-48bf-a3cc-e792cce11b58@googlegroups.com>
References: <37cd1025-2b18-48bf-a3cc-e792cce11b58@googlegroups.com>
Message-ID: <22453b31-465e-4da2-8ac9-28dbe7f4bbc7@googlegroups.com>

By the way, Im using python 2.7.

Thanks


From lac at openend.se  Sun Nov  1 16:48:28 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 01 Nov 2015 22:48:28 +0100
Subject: installer user interface glitch ?
In-Reply-To: <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
Message-ID: <201511012148.tA1LmSop023373@fido.openend.se>

Actually, adding the XP - do not look here --
message for several webpages has been on the pydotorg
todo list for more than a week now.

Not sure why it hasn't happened.

Thank you for the reminder.

Laura


From rosuav at gmail.com  Sun Nov  1 17:03:19 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 09:03:19 +1100
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <87y4ehzeli.fsf@nightsong.com>
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
 <mailman.22.1446388053.4463.python-list@python.org>
 <87y4ehzeli.fsf@nightsong.com>
Message-ID: <CAPTjJmqO4XZiq6d5K3k0WUNdaaWY1GvGfpTPZPO_gtHZTSaazg@mail.gmail.com>

On Mon, Nov 2, 2015 at 6:47 AM, Paul Rubin <no.email at nospam.invalid> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>> We teach 3.4 (because that's what's available on the Ubuntu VMs that
>> we're recommending; anything 3.2+ will probably work just the same),
>> and that's it.
>
> The async keyword seems like one of Py3's bigger improvements and it
> makes its appearance in 3.5, iirc.

Yeah. Not currently available to us, since we're recommending (for
consistency) that students use the Cloud 9 browser-based IDE, but I'm
sure when Ubuntu's next LTS comes out, it'll include 3.5 (or maybe
3.6), so we'll start using that then.

Taking advantage of new features can be done as we decide they're safe
to use, without needing any backward compatibility breaks (apart from,
of course, the async/await code not working on older Pythons). Hmm.
Maybe this should be a workshop... that could be fun.

ChrisA


From rosuav at gmail.com  Sun Nov  1 17:11:55 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 09:11:55 +1100
Subject: PyPy subprocess
In-Reply-To: <37cd1025-2b18-48bf-a3cc-e792cce11b58@googlegroups.com>
References: <37cd1025-2b18-48bf-a3cc-e792cce11b58@googlegroups.com>
Message-ID: <CAPTjJmqziciO0LGuNfDr6De1H4y2Zs_5khFpsY_Ax5Oe-fiscg@mail.gmail.com>

On Mon, Nov 2, 2015 at 8:27 AM, LJ <luisjosenovoa at gmail.com> wrote:
> Im wondering if there is a way in which I can use PyPy to solve the just subproblems in parallel, and return to CPython for the overall routines.
>

You could. What you'd have would be a setup where the subprocess is
utterly independent of the parent; the fact that they both happen to
be written in Python is almost immaterial. Figure out some way of
telling the subprocess what it needs to do (eg command-line parameters
coming through into sys.argv), and getting a response back (eg writing
something to stdout before terminating), and then you can use the
subprocess module to spin off the pypy processes, then (maybe after
doing some other work) wait for each of them to finish.

The subproblem solver could be written in any language at all, here;
there's complete decoupling. If you need to pass a lot of info down
into them, or up and out again, you'll need to serialize it all into
JSON and use stdin/stdout, or something like that. Takes some care,
but it works beautifully... I once had a "Python in Python" setup like
that to make my Python-based web site trigger something in a newer
version of Python than was shipped with my OS (think of a 2.7 invoking
a 3.5 script - I don't remember the actual versions but it was
something like that).

ChrisA


From robertvstepp at gmail.com  Sun Nov  1 17:28:00 2015
From: robertvstepp at gmail.com (boB Stepp)
Date: Sun, 1 Nov 2015 16:28:00 -0600
Subject: installer user interface glitch ?
In-Reply-To: <201511012148.tA1LmSop023373@fido.openend.se>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
 <201511012148.tA1LmSop023373@fido.openend.se>
Message-ID: <CANDiX9JbCUkrdLivXV4haCwddQLHeQ12i-FmKeK5-rBKtrD3Kw@mail.gmail.com>

On Sun, Nov 1, 2015 at 3:48 PM, Laura Creighton <lac at openend.se> wrote:
> Actually, adding the XP - do not look here --
> message for several webpages has been on the pydotorg
> todo list for more than a week now.
>
> Not sure why it hasn't happened.
>
> Thank you for the reminder.

I have to confess I do not understand all of the hullabaloo generated
in this thread, but I think it would be helpful if there were an
obviously placed minimum requirements note for the download page.
Something like "Requires Windows Vista or greater ...", etc.  I
imagine many people are like myself, just trying to learn Python and
want the latest version, etc.  Many software products include a
minimum requirements statement on their download page, so--at least to
me--it does not seem unreasonable for the Python folks to do the same.
If nothing else it might reduce the number of recent XP users from
asking the same questions over, and, ..., and over.  Of course if such
people would only type in their issue into their favorite search
engine...  But that is a different issue--heavy sigh!

-- 
boB


From rosuav at gmail.com  Sun Nov  1 17:38:10 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 09:38:10 +1100
Subject: installer user interface glitch ?
In-Reply-To: <CANDiX9JbCUkrdLivXV4haCwddQLHeQ12i-FmKeK5-rBKtrD3Kw@mail.gmail.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
 <201511012148.tA1LmSop023373@fido.openend.se>
 <CANDiX9JbCUkrdLivXV4haCwddQLHeQ12i-FmKeK5-rBKtrD3Kw@mail.gmail.com>
Message-ID: <CAPTjJmpfeQkbxqjMRX59fxmG0A_0uqNq9Fi9+saUhuNJyGq=aQ@mail.gmail.com>

On Mon, Nov 2, 2015 at 9:28 AM, boB Stepp <robertvstepp at gmail.com> wrote:
> Of course if such
> people would only type in their issue into their favorite search
> engine...  But that is a different issue--heavy sigh!

In their defense, "the installer for Python has a blank window" isn't
nearly as internet-searchable as an actual text error message - plus
the problem exhibits itself in a number of different ways (probably
relating to exactly what parts of XP are available, or something).
Once there's a clear error message saying that this Python doesn't
work on this Windows, it'll be easy for people to look up info on it,
and then find a fully-supported Python 3.4 installer.

ChrisA


From ben+python at benfinney.id.au  Sun Nov  1 17:48:42 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 02 Nov 2015 09:48:42 +1100
Subject: Python 2 vs Python 3 for teaching
References: <CAPTjJmoPtk30rzoDOFnN5evRrd3kDtvie1E1F0Wu_DxWTsc+jA@mail.gmail.com>
 <CAJ4+4apy=ibu4r6d5vj707xoLYEty7MdaOtE+9oi3VOnehB+XA@mail.gmail.com>
Message-ID: <854mh5mj3p.fsf@benfinney.id.au>

<paul.hermeneutic at gmail.com> writes:

> This would make an excellent opportunity to develop a curriculum to
> teach students how to maintain a 2.x and 3.x code base using 2to3.

The advice today reflects the great progress that has been made over
many years of migrating projects and organisations to Python 3.

Instead of ?2to3?, the best advice today is: write new code targeting
Python 3 directly, and only if necessary back-port to Python 2.

> 2.x is not going away as fast as some would like.

Likewise, Python 3 as a primary development target is not as difficult
as some would fear.

Python 2 is unarguably a legacy platform, but it has good support for
receiving code carefully targeting both Python 2 and Python 3. So it's
best to target Python 3 primarily, and back-port code to Python 2 only
as and when needed.

-- 
 \       ?We jealously reserve the right to be mistaken in our view of |
  `\      what exists, given that theories often change under pressure |
_o__)              from further investigation.? ?Thomas W. Clark, 2009 |
Ben Finney



From tjreedy at udel.edu  Sun Nov  1 18:12:27 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 1 Nov 2015 18:12:27 -0500
Subject: Multithreading python,two tkinter windows
In-Reply-To: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
References: <271f8b42-da03-40fd-8a8b-c562292577e6@googlegroups.com>
Message-ID: <n16693$of4$1@ger.gmane.org>

On 11/1/2015 9:05 AM, Vindhyachal Takniki wrote:
> I have made a python code & using multithreading in it. this is very basic code, not using queues & other stuff.

You can run multiple windows, or one window with multiple panes, in one 
thread with one event loop.  Best to do gui stuff in the main thread and 
only use other threads for things that would block.  I see that you 
already know how to use .after to loop.  You can have multiple .after 
loops, with different delays, in one thread.

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Sun Nov  1 19:07:38 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 1 Nov 2015 19:07:38 -0500
Subject: UNABLE TO GET IDLE TO RUN
In-Reply-To: <201511011617.tA1GHVKE030820@fido.openend.se>
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <201511011617.tA1GHVKE030820@fido.openend.se>
Message-ID: <n169gj$7ju$1@ger.gmane.org>

On 11/1/2015 11:17 AM, Laura Creighton wrote:

> In a message of Mon, 02 Nov 2015 01:27:23 +1100, "Steven D'Aprano" writes
> a reply to Michael Overtoon:

He was actually responding to my proposal to warn about duplicating 
stdlib names when saving-as.

>> Users are inclined to ignore alerts, dialogs and error messages, and
>> applications try very, very hard to reinforce that tendency.
>
> http://ux.stackexchange.com/questions/4518/should-alert-boxes-be-avoided-at-any-cost

I read this and at least some of the concerns do not apply.

* IDLE does not spam users with alerts.  And I may move some of the rare 
ones to a new 'log' window. The only one I see with any regularity is 
'Save work before close?' and that I appreciate.

* 'Save-as' is not part of the regular workflow.  It is done once per 
file.  Experienced users who know to avoid stdlib names will not see the 
messages unless they accidentally duplicate one -- which is possible 
because there are now so many.  I personally would like being warned.

* The target of the message is naive beginners who have not read any 
docs and who may not yet even know about the stdlib and imports.  The 
*need* the info and may not be so jaded about alert messages.

One person suggested something I thought about: make the 'right thing' 
box bigger than the 'dangerous thing' box.

>> Good to see that IDLE is going to continue that fine old tradition of
>> degrading usability for the sake of a quick and easy non-solution to a
>> problem.

Doing nothing is also a non-solution.

> I have a professional carreer based on saying 'do not blather useless
> error/warning messages' at people.  I am pretty much always on your
> side of the argument.  But, here we are, first time in 22 years, and
> I am here arguing in _favour_ of a warning message. :)

Knowing that you are not a fan of such things makes your request stronger.

 > I very much want to convince Michael that my warning will be
 > sufficient,

If the message works half the time, I would consider it successful.

 > thus preventing people from writing out strings.py is unnecessary.

I will not absolutely prevent duplicate names unless Guido says to do so.

-- 
Terry Jan Reedy



From danieljoffe at comcast.net  Sun Nov  1 19:08:44 2015
From: danieljoffe at comcast.net (Daniel Joffe)
Date: Sun, 1 Nov 2015 18:08:44 -0600
Subject: python doesn't install
Message-ID: <5636A98C.6030203@comcast.net>

WinXP...32 bits...professional

I keep getting message


note also that there is no place on the install box to start...you just 
click somewhere, and the install started.



From no.email at nospam.invalid  Sun Nov  1 19:50:04 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Sun, 01 Nov 2015 16:50:04 -0800
Subject: UNABLE TO GET IDLE TO RUN
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se>
 <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se>
 <n114n1$o4h$1@ger.gmane.org> <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <201511011617.tA1GHVKE030820@fido.openend.se>
 <mailman.43.1446422879.4463.python-list@python.org>
Message-ID: <87twp5z0lf.fsf@nightsong.com>

Terry Reedy <tjreedy at udel.edu> writes:
> * 'Save-as' is not part of the regular workflow.  It is done once per
> file.  Experienced users who know to avoid stdlib names will not see
> the messages unless they accidentally duplicate one -- which is
> possible because there are now so many.  I personally would like being
> warned.

I think there is something to be said for this.  I've gotten confused a
few times by accidentally re-using a stdlib name, and I'm experienced.

One thing I wish in IDLE is for ctrl-N (or some alternate) to prompt
for a filename immediately: opening a new window, then writing code in
it, and then using Save-as seems unnatural to me.  That would also be
a good time to validate the filename, by searching sys.path or whatever.


From tjreedy at udel.edu  Sun Nov  1 19:50:38 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 1 Nov 2015 19:50:38 -0500
Subject: installer user interface glitch ?
In-Reply-To: <CANDiX9JbCUkrdLivXV4haCwddQLHeQ12i-FmKeK5-rBKtrD3Kw@mail.gmail.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
 <201511012148.tA1LmSop023373@fido.openend.se>
 <CANDiX9JbCUkrdLivXV4haCwddQLHeQ12i-FmKeK5-rBKtrD3Kw@mail.gmail.com>
Message-ID: <n16c16$5bn$1@ger.gmane.org>

On 11/1/2015 5:28 PM, boB Stepp wrote:
> On Sun, Nov 1, 2015 at 3:48 PM, Laura Creighton <lac at openend.se> wrote:
>> Actually, adding the XP - do not look here --
>> message for several webpages has been on the pydotorg
>> todo list for more than a week now.
>>
>> Not sure why it hasn't happened.
>>
>> Thank you for the reminder.
>
> I have to confess I do not understand all of the hullabaloo generated
> in this thread, but I think it would be helpful if there were an
> obviously placed minimum requirements note for the download page.
> Something like "Requires Windows Vista or greater ...", etc.

I agree.  A Minimum Requirements box is pretty standard on both boxes 
and web pages.  For Python, a sentence suffices.

-- 
Terry Jan Reedy



From steve at pearwood.info  Sun Nov  1 19:54:45 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 11:54:45 +1100
Subject: UNABLE TO GET IDLE TO RUN
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <mailman.29.1446394667.4463.python-list@python.org>
Message-ID: <5636b458$0$1622$c3e8da3$5496439d@news.astraweb.com>

On Mon, 2 Nov 2015 03:17 am, Laura Creighton wrote:

> I managed to delete the real mail I would like to reply to.
> This is, at least in the same thread ....
> 
> In a message of Mon, 02 Nov 2015 01:27:23 +1100, "Steven D'Aprano" writes
> a reply to Michael Overtoon:

Actually it's a reply to Terry.


>> Users are inclined to ignore alerts, dialogs and error messages, and
>> applications try very, very hard to reinforce that tendency.
> 
>
http://ux.stackexchange.com/questions/4518/should-alert-boxes-be-avoided-at-any-cost
> 
> (ok posting of question.)
> 
>> Good to see that IDLE is going to continue that fine old tradition of
>> degrading usability for the sake of a quick and easy non-solution to a
>> problem.
> 
> I think you owe Michael an apology.

I can't imagine why you think I owe Michael an apology. An apology for what?


> Winning an argument on  'I should I get it my way because I can come up
> with a pithy and condescending way to phrase my objection to what you
> want to do' seems morally bankrupt to me.  Ditto on the idea of bashing
> him just because he is handy and the world is a bad place for you right
> now.  

"Bashing" him? Really? A touch of sarcasm ("Good to see") about a technical
decision is bashing the author and "morally bankrupt"?

Laura, with respect, perhaps it isn't me who is writing from "a bad place"
right now.


> It hardly counts as a technical reason for or against the issuing 
> of warnings in idle, or the more severe 'not allowing you to save'.

There is a technical reason against the issuing of warnings in IDLE, namely
that their target audience is disinclined to read warnings, not well suited
to understand these specific warnings, and likely to click on whatever
random buttons it takes to make the warnings go away and let them save
their file under their chosen name.


> I have a professional carreer based on saying 'do not blather useless
> error/warning messages' at people.  I am pretty much always on your
> side of the argument.  But, here we are, first time in 22 years, and
> I am here arguing in _favour_ of a warning message. :)

I get that, I truly do, and believe me when I say I respect your expertise.
But it seems to me that you're falling for the fallacy "we must do
something, this is something, therefore we must do it".

I completely agree that accidental shadowing is a problem, especially for
beginners. I too would like to fix that, and (as you know, but others may
not) I've proposed a solution on the Python-Ideas mailing list.

But just because there is a problem doesn't mean that the first thing we
think of is the solution. I haven't come across anyone, not one person,
willing to dispute the conventional wisdom that users don't read alert
messages. We agree that users don't read warnings, but you're expecting
them to read *this* warning. What makes this proposed warning different
from all the other useless blatherings that users don't read? Why will they
read this one?

It is 2015, nearly 2016, and surely there isn't a professional developer
alive who hasn't come across the truism that users don't read warnings, and
that they should avoid putting up modal dialogs with a warning. And yet
they still do it. Why?

They're not all idiots. I don't believe either you or Terry are idiots. I
expect that, like you and Terry, they have fallen into the trap of
believing that *this one case is special*. This issue is important enough
that we have to do something, and users might not read all those other
blathering error messages, but they'll read this one, because it is
important that they do.

Otherwise, how can you justify this warning? Users won't read it. It will
just reinforce their tendency to ignore errors and warnings, and as an
educator surely you don't want that. If they click on the OK/Cancel button
at random, as UI studies suggest people tend to do, then 50% will end up
shadowing the file regardless, and 50% will have a second chance to pick a
better name -- which they may not do.

And most shadowing is harmless. If I name my script code.py, or this.py, it
will still run fine unless I directly or indirectly import `code` or
`this`. It is true that shadowing *can* leave Python effectively unusable
(try shadowing `os` and see how many things break) but most of the time
shadowing doesn't hurt. So most of the time, these warnings will be exactly
the pointless blatherings that you usually oppose.



-- 
Steven



From tjreedy at udel.edu  Sun Nov  1 20:02:30 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 1 Nov 2015 20:02:30 -0500
Subject: installer user interface glitch ?
In-Reply-To: <A8BF5D25-7072-44F1-A4D5-680B0DA7EE65@xs4all.nl>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <A8BF5D25-7072-44F1-A4D5-680B0DA7EE65@xs4all.nl>
Message-ID: <n16cnf$kh4$1@ger.gmane.org>

On 11/1/2015 10:54 AM, Michiel Overtoom wrote:
>
>> On 01 Nov 2015, at 16:43, rurpy--- via Python-list
>> <python-list at python.org> wrote:
>>
>> Why, oh why, do the python.org front page and other pages that
>> offer a Windows download not say a word about it not running on
>> Windows XP?
>
> I'm also curious why Python 3.5 won't run on Windows XP. Which
> features does it use that require Windows 7 or higher?

The initial issue was some system functions that are new in Vista.  Then 
came MS's new-with-Win10 toolset that does not support XP.

> Or is the
> decision to not support Windows XP based on Microsoft ending the
> product support lifecycle for XP?

As I explained in another message, it was the other way around, in a 
sense.  As long as MS supported XP, Windows CPython devs either 
refrained from using new not-in-xp features or maintained old 
workarounds.  The has been more or less the same policy for other 
versions of Windows.


-- 
Terry Jan Reedy



From steve at pearwood.info  Sun Nov  1 20:19:57 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 12:19:57 +1100
Subject: UNABLE TO GET IDLE TO RUN
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org> <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <201511011617.tA1GHVKE030820@fido.openend.se>
 <mailman.43.1446422879.4463.python-list@python.org>
Message-ID: <5636ba40$0$1600$c3e8da3$5496439d@news.astraweb.com>

On Mon, 2 Nov 2015 11:07 am, Terry Reedy wrote:

> On 11/1/2015 11:17 AM, Laura Creighton wrote:
> 
>> In a message of Mon, 02 Nov 2015 01:27:23 +1100, "Steven D'Aprano" writes
>> a reply to Michael Overtoon:
> 
> He was actually responding to my proposal to warn about duplicating
> stdlib names when saving-as.
> 
>>> Users are inclined to ignore alerts, dialogs and error messages, and
>>> applications try very, very hard to reinforce that tendency.
>>
>>
http://ux.stackexchange.com/questions/4518/should-alert-boxes-be-avoided-at-any-cost
> 
> I read this and at least some of the concerns do not apply.
> 
> * IDLE does not spam users with alerts.

IDLE might not, but they will be using a computer that does. 

And frankly, I don't believe that users don't read alerts because they are
spammed by them. I've seen far too many new computer users who have not had
time to get jaded by excessive alerts click through without reading.

Certainly the excessive use of warnings makes the problem worse, teaching
even experienced users to ignore them. But that's not where the problem
starts.

We all agree on the nature of the problem, we all agree that the evidence
from systematic UI testing is that the general solution proposed ("put up a
warning dialog") is likely to be pointless, and yet some of us are sure
that the evidence doesn't apply in this case, this case is special.

I don't believe it is.


[...]
>>> Good to see that IDLE is going to continue that fine old tradition of
>>> degrading usability for the sake of a quick and easy non-solution to a
>>> problem.
> 
> Doing nothing is also a non-solution.

Some people may argue that Python has survived for over two decades with
this problem, so that "do nothing" is a perfectly valid thing to do.

But I haven't argued for "do nothing". I've offered two solutions:

- Python as a whole should move "" from the start of sys.path to the end (or
at least the middle, after the stdlib) so as to avoid accidental shadowing.

- Even if Python doesn't do this, IDLE could do it, and could do it
immediately, without waiting for a new point release. IDLE is an
application, an IDE, not the Python interpreter, and like IPython or any
other IDE, it is perfectly entitled to behave differently from the vanilla
Python interpreter.

I argue that IDLE is entitled to do anything which the site module or
PYTHONSTARTUP file could do, such as pre-import the most common modules, or
change the order of sys.path. As maintainer, you're entitled to reject my
solution. But it is a potential solution, and I believe it will come closer
to an actual fix for the shadowing issue than raising warnings.



-- 
Steven



From steve at pearwood.info  Sun Nov  1 20:32:23 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 12:32:23 +1100
Subject: installer user interface glitch ?
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
Message-ID: <5636bd2a$0$1616$c3e8da3$5496439d@news.astraweb.com>

On Mon, 2 Nov 2015 03:43 am, Chris Angelico wrote:

> Remember, people can click a direct download link
> *on the python.org front page* and be immediately downloading Python 2
> or 3 for the OS that the browser announces. Where would you put the
> big fat noisy warning?

Maybe the website shouldn't do that then.

Seriously, if the browser announces Windows XP, it's probably not a good
idea to download a version which is known not to work with XP...



-- 
Steven



From rosuav at gmail.com  Sun Nov  1 20:50:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 12:50:42 +1100
Subject: installer user interface glitch ?
In-Reply-To: <5636bd2a$0$1616$c3e8da3$5496439d@news.astraweb.com>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <5636bd2a$0$1616$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmo4b0XhS_8fWyTKW1YdRyNeSjfMNLeR_+=Ue7dhdHJVxA@mail.gmail.com>

On Mon, Nov 2, 2015 at 12:32 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Mon, 2 Nov 2015 03:43 am, Chris Angelico wrote:
>
>> Remember, people can click a direct download link
>> *on the python.org front page* and be immediately downloading Python 2
>> or 3 for the OS that the browser announces. Where would you put the
>> big fat noisy warning?
>
> Maybe the website shouldn't do that then.
>
> Seriously, if the browser announces Windows XP, it's probably not a good
> idea to download a version which is known not to work with XP...

Maybe Laura would know how plausible this is, but...

I expect most people who go to the front page are looking for the "one
most obvious download". (Okay, we have two - 2.7 and 3.x - but leaving
that aside.) There's detection of what your OS is, which then selects
an appropriate download file; it'd be really cool if a browser UA that
represents XP would cause the link to point to 3.4 instead of 3.5. Or
would that cause more confusion than it solves?

ChrisA


From rosuav at gmail.com  Sun Nov  1 21:08:10 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 2 Nov 2015 13:08:10 +1100
Subject: UNABLE TO GET IDLE TO RUN
In-Reply-To: <5636ba40$0$1600$c3e8da3$5496439d@news.astraweb.com>
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0ccgu$uj9$1@ger.gmane.org>
 <201510230905.t9N95FPe025528@fido.openend.se>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se>
 <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se>
 <n114n1$o4h$1@ger.gmane.org> <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <201511011617.tA1GHVKE030820@fido.openend.se>
 <mailman.43.1446422879.4463.python-list@python.org>
 <5636ba40$0$1600$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmojDi-GzRGfHV6fDAhmDuAff7z8KZ=OEgxU9hztvRjd9g@mail.gmail.com>

On Mon, Nov 2, 2015 at 12:19 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> - Python as a whole should move "" from the start of sys.path to the end (or
> at least the middle, after the stdlib) so as to avoid accidental shadowing.
>
> - Even if Python doesn't do this, IDLE could do it, and could do it
> immediately, without waiting for a new point release. IDLE is an
> application, an IDE, not the Python interpreter, and like IPython or any
> other IDE, it is perfectly entitled to behave differently from the vanilla
> Python interpreter.

IDLE consists of two things: its own code, and a means of running user
code. Conceptually, they're entirely separate - it's almost a
coincidence that they happen to be using the same language. If the IDE
wants to protect itself against running unexpected userland modules,
it is absolutely allowed to do that, same as any other application is;
it can remove "" from sys.path, or reposition it, or add traps to see
where some_module.__file__ is, or anything at all.

But when it's running user code, it should be semantically as close as
possible to the command-line interpreter as it can be. If I type
"import foo" into IDLE's interactive mode, or if I type "import foo"
into IDLE's editor and hit Run, or if I type "import foo" into the
standard command-line interactive interpreter, I expect that they'll
all find the same module, and if they don't, it's an extra debugging
hassle. When I'm debugging a script, I'll often try some parts of it
in an interactive interpreter, and it should not matter whether I pick
"python", or Idle, or ipython in a terminal window, or the in-browser
ipython notebook, etc, etc, etc. I want to be able to keep the
differences *in my head*. There are already a few; interactive
interpreters...

* Can't have blank lines in class/function definitions;
* Automatically print non-None expression results;
* Recover from exceptions by returning to the main loop, rather than
bombing the whole module load
* Warnings are enabled by default

AFAIK, all of these are consistent across _all_ interactive Python
interpreters. (The second one is configurable, but it's always the
default.) I do *not* want to have to add "Local modules do not shadow
stdlib modules" as an additional difference, particularly not in one
specific interface and not others.

So yes, technically IDLE is allowed to behave differently. But I would
hope this is extremely rare and VERY solidly justified (eg "Python 3.6
will do it this way, and IDLE is a bit ahead of the curve").

ChrisA


From chris at simplistix.co.uk  Sun Nov  1 23:08:46 2015
From: chris at simplistix.co.uk (Chris Withers)
Date: Sun, 1 Nov 2015 22:08:46 -0600
Subject: testfixtures 4.4.0 Released!
Message-ID: <5636E1CE.7080500@simplistix.co.uk>

Hi All,

I'm pleased to announce the release of testfixtures 4.4.0. This is a 
feature release that adds the following:

- Add support for labelling the arguments passed to compare().

- Allow expected and actual keyword parameters to be passed to
   compare().

- Fix "TypeError: unorderable types" when compare() found multiple
   differences in sets and dictionaries on Python 3.

- Add official support for Python 3.5.

- Drop official support for Python 2.6.

Thanks to Daniel Fortunov for the initial ideas for explicit expected 
and actual support in compare().

The package is on PyPI and a full list of all the links to docs, issue 
trackers and the like can be found here:

https://github.com/Simplistix/testfixtures

Any questions, please do ask on the Testing in Python list or on the 
Simplistix open source mailing list...

cheers,

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
            - http://www.simplistix.co.uk


From amnaee at gmail.com  Mon Nov  2 00:30:19 2015
From: amnaee at gmail.com (amnaee at gmail.com)
Date: Sun, 1 Nov 2015 21:30:19 -0800 (PST)
Subject: Problem in implementing Romania Map using Paython Script
Message-ID: <24e4a4ca-59d1-433e-a0ed-fa04fc23041d@googlegroups.com>

Dear all;

I want to code algorithm in Python for driving from Arad to Bucharest as quickly as possible.

I formulated the problem in python as following :
1- States : Various cities.
2- Actions : Drive distances between different cities.
3- Goal : To be in Bucharest.

class Problem:
    def __init__(self, initial, goal=None):
       
        self.initial = initial
        self.goal = goal
        
    def goalTest(self, state):
        
        return state == self.goal

But the problem now is with Roaming and Node classifications :

class RoamingProblem(Problem):   
    def successors(self, state):

Q1 : How I can complete the class RoamingProblem (Problem) and include action costs.
I think its related in some how in using a new city map ????...
And how I can return the cost next state  ????...

list of tuples [(action1,[(action1, successor-state1, cost1, action2, successor-state2, cost2 ...)]

Q2 : For the class node 
class Node:
    def __init__(self, state, parent=None, action=None, pathCost=0):
        self.state = state
        self.parent = parent
        self.action = action
        self.pathCost = pathCost
        update(state,parent,action,pathcost,depth)
    def expand(self, problem):
        
        return [Node(next,self,action,problem,....].

THE last line How I can return : list of Node objects, one for each successor state, parent of the created nodes is self ????....

I need a help in completing the Class Roaming problem using Euclidean function , Completing the Class Node .....

And def treesearch and graph search problem ?????

Waiting for reply ????



From ben+python at benfinney.id.au  Mon Nov  2 00:45:50 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 02 Nov 2015 16:45:50 +1100
Subject: Problem in implementing Romania Map using Paython Script
References: <24e4a4ca-59d1-433e-a0ed-fa04fc23041d@googlegroups.com>
Message-ID: <85ziyxkl81.fsf@benfinney.id.au>

amnaee at gmail.com writes:

> I need a help in completing the Class Roaming problem using Euclidean
> function , Completing the Class Node .....

I think you need to research how to solve this algorithm, and only
*then* think about how to code it in Python.

Is this a homework assignment?

> And def treesearch and graph search problem ?????
>
> Waiting for reply ????

You may not intend it, but adding multiple question marks communicates
urgent insistence, and is rather rude in a request to a community of
volunteers.

-- 
 \         ?I may disagree with what you say, but I will defend to the |
  `\        death your right to mis-attribute this quote to Voltaire.? |
_o__)                   ?Avram Grumer, rec.arts.sf.written, 2000-05-30 |
Ben Finney



From mail at timgolden.me.uk  Mon Nov  2 01:16:25 2015
From: mail at timgolden.me.uk (Tim Golden)
Date: Mon, 2 Nov 2015 06:16:25 +0000
Subject: python doesn't install
In-Reply-To: <5636A98C.6030203@comcast.net>
References: <5636A98C.6030203@comcast.net>
Message-ID: <5636FFB9.8040703@timgolden.me.uk>

On 02/11/2015 00:08, Daniel Joffe wrote:
> WinXP...32 bits...professional
>
> I keep getting message
>
>
> note also that there is no place on the install box to start...you just
> click somewhere, and the install started.
>

I'm afraid you've been bitten by the fact that we no longer support 
Windows XP and haven't communicated this very well. We have a new 
version of the installer almost ready for release which indicates this 
much earlier (and more obviously). I'm afraid if you're on XP you're 
limited to Python 3.4 and earlier, all of which are perfectly usable I'm 
happy to say!

TJG


From auriocus at gmx.de  Mon Nov  2 01:45:32 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Mon, 2 Nov 2015 07:45:32 +0100
Subject: Problem in implementing Romania Map using Paython Script
In-Reply-To: <24e4a4ca-59d1-433e-a0ed-fa04fc23041d@googlegroups.com>
References: <24e4a4ca-59d1-433e-a0ed-fa04fc23041d@googlegroups.com>
Message-ID: <n170m7$gnj$1@dont-email.me>

Am 02.11.15 um 06:30 schrieb amnaee at gmail.com:
> Dear all;
>
> I want to code algorithm in Python for driving from Arad to Bucharest as quickly as possible.
>

It sounds a lot like a homework problem. If so, look into your notes for 
"Dijkstra algorithm", or "A* algorithm". If not, look for a library that 
does routing or make an API call to graphhopper, Google maps or similar. 
Routing (esp. fast routing) is a non-trivial problem.

	Christian



From tjreedy at udel.edu  Mon Nov  2 02:46:45 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 2 Nov 2015 02:46:45 -0500
Subject: UNABLE TO GET IDLE TO RUN
In-Reply-To: <87twp5z0lf.fsf@nightsong.com>
References: <1501485483.555358.1445441061800.JavaMail.yahoo@mail.yahoo.com>
 <n0cvev$nhn$1@ger.gmane.org> <n0d0lm$cm3$1@ger.gmane.org>
 <n0lbd3$pin$1@ger.gmane.org> <n0mb0v$tel$1@ger.gmane.org>
 <n0nbr7$4jp$1@ger.gmane.org> <n0nmij$k8b$1@ger.gmane.org>
 <n0qs2l$8t8$1@ger.gmane.org> <56310743.3070708@gmail.com>
 <n0r3me$e50$1@ger.gmane.org> <563180CB.5080303@gmail.com>
 <201510290753.t9T7rZqR032272@fido.openend.se> <n0ssmm$adi$1@ger.gmane.org>
 <5A7F323C-ED4A-4CCA-A392-2C6F64EA6A6F@xs4all.nl>
 <201510301629.t9UGTY2i013568@fido.openend.se> <n114n1$o4h$1@ger.gmane.org>
 <n11lcd$snp$1@ger.gmane.org>
 <mailman.3.1446342360.4463.python-list@python.org>
 <5636214b$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <201511011617.tA1GHVKE030820@fido.openend.se>
 <mailman.43.1446422879.4463.python-list@python.org>
 <87twp5z0lf.fsf@nightsong.com>
Message-ID: <n174dd$ba$1@ger.gmane.org>

On 11/1/2015 7:50 PM, Paul Rubin wrote:
> Terry Reedy <tjreedy at udel.edu> writes:
>> * 'Save-as' is not part of the regular workflow.  It is done once per
>> file.  Experienced users who know to avoid stdlib names will not see
>> the messages unless they accidentally duplicate one -- which is
>> possible because there are now so many.  I personally would like being
>> warned.
>
> I think there is something to be said for this.  I've gotten confused a
> few times by accidentally re-using a stdlib name, and I'm experienced.
>
> One thing I wish in IDLE is for ctrl-N (or some alternate) to prompt
> for a filename immediately: opening a new window, then writing code in
> it, and then using Save-as seems unnatural to me.  That would also be
> a good time to validate the filename, by searching sys.path or whatever.

Given that one has to save-as before running, this seems somewhat 
sensible.  There is also request to be able to run 'Untitled' windows.

-- 
Terry Jan Reedy



From steve+comp.lang.python at pearwood.info  Mon Nov  2 02:52:55 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Mon, 02 Nov 2015 18:52:55 +1100
Subject: Unbuffered stderr in Python 3
Message-ID: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>

In Python 2, stderr is unbuffered.

In most other environments (the shell, C...) stderr is unbuffered.

It is usually considered a bad, bad thing for stderr to be buffered. What 
happens if your application is killed before the buffer fills up? The errors 
in the buffer will be lost.

So how come Python 3 has line buffered stderr? And more importantly, how can 
I turn buffering off?

I don't want to use the -u unbuffered command line switch, because that 
effects stdout as well. I'm happy for stdout to remain buffered.


Here is the function I'm using to test this in in the interactive 
interpreter:

import sys, time

def test():
    # Simulate a slow calculation that prints status and/or error
    # messages to stderr.
    for i in range(10):
        print(i, file=sys.stderr, end="")
        time.sleep(2)
    print("", file=sys.stderr)


Running it pauses for 20 seconds, then displays "0123456789" in one go. What 
I expect is to see the digits arrive individually.

I tried this:

py> sys.stderr.line_buffering = False
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: readonly attribute


Next I tried this:

py> sys.stderr.buffer.line_buffering = False


which succeeded, but has no effect on print: it still buffers.




-- 
Steve



From df at see.replyto.invalid  Mon Nov  2 03:28:58 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Mon, 02 Nov 2015 08:28:58 +0000
Subject: python doesn't install
References: <5636A98C.6030203@comcast.net>
 <mailman.51.1446444994.4463.python-list@python.org>
Message-ID: <je5e3bdo94nr68k9dho41243s7s97hcqlp@4ax.com>

Tim Golden <mail at timgolden.me.uk> wrote:

>I'm afraid you've been bitten by the fact that we no longer support 
>Windows XP and haven't communicated this very well. We have a new 
>version of the installer almost ready for release which indicates this 
>much earlier (and more obviously). I'm afraid if you're on XP you're 
>limited to Python 3.4 and earlier, all of which are perfectly usable I'm 
>happy to say!

I've been reading the comments about Python and XP on this group -- and
I must say that I'm thinking: Doesn't pretty much every other Windows
software package tell you the minimum requirements -- because that's the
first thing you'd want to know?

So I've Googled for "python 3.5 minimum requirements":

1st hit: "Using Python on Windows -- Python 3.5.0 documentation"
and a few paragraphs down that page there's:
"Python on XP --  7 Minutes to Hello World by Richard Dooling, 2006"
which says how easy it is to install on XP.

2nd hit: "Download Python -- Python.org"
There's download links but nothing about XP, but there's a link for
"Information about specific ports" -- so click on "Windows"
and no information actually, just more download links.

3rd hit: "Welcome to Python.org"
There's download links and no info about minimum requirements.

And so on down the page of Google hits.

Yes, I've read the justifications. Why list all the non-supported OSs?
And the explanation about each version of Python being supported just
for the supported versions of Windows upon its release is in the
documentation -- somewhere.  But it still seems to me that stating the
minimum requirements in a place that people would tend to look for it is
a... minimum requirement.

If the developers really are determined not to mention specific versions
of Windows (If it was me, I'd have probably mentioned that the most
recent version required Vista somewhere on the download page), then
maybe adding the comment about matching the release date of Python to
the supported versions of Windows to the download pages would give
people some sort of clue as to what's going on.


From mail at timgolden.me.uk  Mon Nov  2 03:32:46 2015
From: mail at timgolden.me.uk (Tim Golden)
Date: Mon, 2 Nov 2015 08:32:46 +0000
Subject: python doesn't install
In-Reply-To: <5636FFB9.8040703@timgolden.me.uk>
References: <5636A98C.6030203@comcast.net> <5636FFB9.8040703@timgolden.me.uk>
Message-ID: <56371FAE.4080903@timgolden.me.uk>

On 02/11/2015 06:16, Tim Golden wrote:
> On 02/11/2015 00:08, Daniel Joffe wrote:
>> WinXP...32 bits...professional
>>
>> I keep getting message
>>
>>
>> note also that there is no place on the install box to start...you just
>> click somewhere, and the install started.
>>
> 
> I'm afraid you've been bitten by the fact that we no longer support
> Windows XP and haven't communicated this very well. We have a new
> version of the installer almost ready for release which indicates this
> much earlier (and more obviously). I'm afraid if you're on XP you're
> limited to Python 3.4 and earlier, all of which are perfectly usable I'm
> happy to say!

Sorry, I omitted to say that you can download the latest Python 3.4 from
here:

https://www.python.org/downloads/release/python-343/

TJG





From kwpolska at gmail.com  Mon Nov  2 04:03:31 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Mon, 2 Nov 2015 10:03:31 +0100
Subject: python doesn't install
In-Reply-To: <je5e3bdo94nr68k9dho41243s7s97hcqlp@4ax.com>
References: <5636A98C.6030203@comcast.net>
 <mailman.51.1446444994.4463.python-list@python.org>
 <je5e3bdo94nr68k9dho41243s7s97hcqlp@4ax.com>
Message-ID: <CAMw+j7J5TDKM3-7ehEmY-bVdaxiY2Z2d1f814=5hSNEJerQsXA@mail.gmail.com>

On 2 November 2015 at 09:28, Dave Farrance <df at see.replyto.invalid> wrote:
> Yes, I've read the justifications. Why list all the non-supported OSs?
> And the explanation about each version of Python being supported just
> for the supported versions of Windows upon its release is in the
> documentation -- somewhere.  But it still seems to me that stating the
> minimum requirements in a place that people would tend to look for it is
> a... minimum requirement.
>
> If the developers really are determined not to mention specific versions
> of Windows (If it was me, I'd have probably mentioned that the most
> recent version required Vista somewhere on the download page), then
> maybe adding the comment about matching the release date of Python to
> the supported versions of Windows to the download pages would give
> people some sort of clue as to what's going on.
> --
> https://mail.python.org/mailman/listinfo/python-list

This could be resolved in one line of HTML or reST. Windows XP is
still in use, and it was supported one minor version ago. Surely it
wouldn?t hurt to add a ?Warning: Windows XP is ancient, and Python 3.5
does not support it ? upgrade to a newer OS or use 3.4.3 instead?
notice to the download page?

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From wolfgang.maier at biologie.uni-freiburg.de  Mon Nov  2 05:48:32 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Mon, 2 Nov 2015 11:48:32 +0100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n17f20$8tt$1@ger.gmane.org>

On 02.11.2015 08:52, Steven D'Aprano wrote:
> In Python 2, stderr is unbuffered.
>
> In most other environments (the shell, C...) stderr is unbuffered.
>
> It is usually considered a bad, bad thing for stderr to be buffered. What
> happens if your application is killed before the buffer fills up? The errors
> in the buffer will be lost.
>
> So how come Python 3 has line buffered stderr? And more importantly, how can
> I turn buffering off?
>

I cannot comment on your first question, but unbuffered writing to 
sys.stderr is possible just like for any other buffered file object. You 
just call its flush method after writing.

Since Python3.3, the print function has a flush keyword argument that 
accepts a boolean and lets you do just this. Rewrite your example as:

import sys, time

def test():
# Simulate a slow calculation that prints status and/or error
# messages to stderr.
for i in range(10):
_print(i, file=sys.stderr, end="", flush=True)
time.sleep(2)
print("", file=sys.stderr)

and it should do what you want.


Before Python 3.3, if I needed an unbuffered print function, I used a 
wrapper to call flush for me, so instead of:

>
> import sys, time
>
> def test():
>      # Simulate a slow calculation that prints status and/or error
>      # messages to stderr.
>      for i in range(10):
>          print(i, file=sys.stderr, end="")
>          time.sleep(2)
>      print("", file=sys.stderr)
>

I'd use (and still do this if I need compatibility with 3.2):

import sys, time

def _print (*args, **kwargs):
    file = kwargs.get('file', sys.stdout)
    print(*args, **kwargs)
    file.flush()

def test():
     # Simulate a slow calculation that prints status and/or error
     # messages to stderr.
     for i in range(10):
         _print(i, file=sys.stderr, end="")
         time.sleep(2)
     print("", file=sys.stderr)

Best,
Wolfgang



From wolfgang.maier at biologie.uni-freiburg.de  Mon Nov  2 05:54:44 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Mon, 2 Nov 2015 11:54:44 +0100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <n17f20$8tt$1@ger.gmane.org>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <n17f20$8tt$1@ger.gmane.org>
Message-ID: <n17fdk$euv$1@ger.gmane.org>

On 02.11.2015 11:48, Wolfgang Maier wrote:
>
> Since Python3.3, the print function has a flush keyword argument that
> accepts a boolean and lets you do just this. Rewrite your example as:
>
> import sys, time
>
> def test():
> # Simulate a slow calculation that prints status and/or error
> # messages to stderr.
> for i in range(10):
> _print(i, file=sys.stderr, end="", flush=True)
> time.sleep(2)
> print("", file=sys.stderr)
>
> and it should do what you want.

sorry for this mess (copy pasted from the wrong source).
The code should be:

def test():
     # Simulate a slow calculation that prints status and/or error
     # messages to stderr.
     for i in range(10):
         print(i, file=sys.stderr, end="", flush=True)
         time.sleep(2)
     print("", file=sys.stderr)




From tjreedy at udel.edu  Mon Nov  2 06:08:31 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 2 Nov 2015 06:08:31 -0500
Subject: Problem in implementing Romania Map using Paython Script
In-Reply-To: <85ziyxkl81.fsf@benfinney.id.au>
References: <24e4a4ca-59d1-433e-a0ed-fa04fc23041d@googlegroups.com>
 <85ziyxkl81.fsf@benfinney.id.au>
Message-ID: <n17g7n$o89$1@ger.gmane.org>

On 11/2/2015 12:45 AM, Ben Finney wrote:
> amnaee at gmail.com writes:
>
>> I need a help in completing the Class Roaming problem using Euclidean
>> function , Completing the Class Node .....
>
> I think you need to research how to solve this algorithm, and only
> *then* think about how to code it in Python.
>
> Is this a homework assignment?

Norquist's AI book uses the Romania map to illustrate search problems. 
Whether this is a class assignment is a different matter, but OP should 
mention it either way.

-- 
Terry Jan Reedy



From danieljoffe at comcast.net  Mon Nov  2 07:35:52 2015
From: danieljoffe at comcast.net (Daniel Joffe)
Date: Mon, 2 Nov 2015 06:35:52 -0600
Subject: same problem even after repair
Message-ID: <563758A8.7010207@comcast.net>



From beliavsky at aol.com  Mon Nov  2 08:15:17 2015
From: beliavsky at aol.com (beliavsky at aol.com)
Date: Mon, 2 Nov 2015 05:15:17 -0800 (PST)
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <mailman.7.1446371003.4463.python-list@python.org>
References: <mailman.7.1446371003.4463.python-list@python.org>
Message-ID: <c6405c34-43cc-417b-9027-12e3ac1bbfb5@googlegroups.com>

I think Python 2.x is still used more than Python 3.x in scientific computing. The Python books I have in this area, such as "Python for Finance: Analyze Big Financial Data" and "Python for Data Analysis", still use Python 2.x . An aspiring computational scientist, data scientist, or financial quant may still be better off learning Python 2.x but using print(x) rather than print x and doing other things to future-proof his code.


From input/ldompeling at casema.nl  Mon Nov  2 08:29:04 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 02 Nov 2015 13:29:04 GMT
Subject: GoPiGo script
References: <d9hnjqF4lbuU1@mid.individual.net>
Message-ID: <AyJZx.1$Gy4.0@fe40.am1>

I tried to use def loop(): now for to restart the script.
but its only restart "fwd()" print ("forward 1x") and then stop.
It does not look further for the if function.
Is there another way to restart this script ?
I also tried with (while True:) but that does nothing.

Thanks


-------------------------------------------------------------------------------
from  gopigo import *
import time


set_right_speed(150)
set_left_speed(105)

enable_servo
mindist = 80
servo(90)
def loop():
    fwd()
    print ("forward 1x")
    time.sleep(2)
    stop()

if mindist > us_dist(15):
    bwd()
    print ("backward 1x",us_dist(15))
    time.sleep(2)
    left_rot()
    print("left rot",us_dist(15))
    time.sleep(3)
    stop()

if mindist < us_dist(15):
    fwd()
    print("forward 2x",us_dist(15))
    time.sleep(2)
    stop()

#for x in range(3):

if mindist > us_dist(15):
    bwd()
    print("backward 2x",us_dist(15))
    time.sleep(2)
    stop()
    right()

else:
     fwd()
     print("forward else",us_dist(15))
     time.sleep(4)
     stop()

if mindist > us_dist(15):
    bwd()
    print("backward 3x")
    time.sleep(2)
    stop()
    left_rot()
    print("left rot")
    time.sleep(1)
    stop()
    mindist = 80
loop()

































In reply to "Peter Pearson" who wrote the following:

> On Fri, 30 Oct 2015 16:58:16 GMT, input/ldompeling at casema.nl wrote:
> > The GoPiGo is a little robot on wheels.
> > 
> > I want that this script restart when its ends.
> > I tried with "while True"and"return"and also "continue"
> > But those functions gives me errors.
> > What for function else can I use to restart this script.
> > 
> [snip]
> > 
> > from gopigo import *
> > import time
> > 
> > 
> > set_right_speed(150)
> > set_left_speed(105)
> > 
> > while True:
> 
> Is this the "while True" that gave you errors?  I think it
> should, since a "while" should be followed by an indented block
> of code.  Perhaps you should use this "while True" to replace
> the "for x in range(3)" near the bottom.
> 
> > #def test():
> > enable_servo()
> > mindist = 80
> > servo(90)
> > fwd()#wheels go forward
> > print ("forward1x")
> > #time.sleep(5)
> > #stop()
> > 
> > if mindist > us_dist(15):
> >      #enc_tgt(1,1,72)
> >     bwd()#wheels go backward
> >     print ("backward1x",us_dist(15))
> >     time.sleep(2)
> >     left_rot()#wheels rotate left
> >     print("left rot",us_dist(15))
> >     time.sleep(3)
> >     stop()
> > 
> > if mindist < us_dist(15):
> >    #enc_tgt(1,1,72)
> >     fwd()#wheels go forward
> >     print("forward2x",us_dist(15))
> >     time.sleep(2)
> >     stop()
> > 
> > for x in range(3):
> > 
> >     if mindist > us_dist(15):
> >          bwd()#wheels go backward
> >          print("backward2x",us_dist(15))
> 
> In future questions, it might help if you explained which of these
> print statements you would like to see executed how many times.
> 
> --
> To email me, substitute nowhere->runbox, invalid->com.




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From hakugin.gin at gmail.com  Mon Nov  2 08:45:09 2015
From: hakugin.gin at gmail.com (hakugin.gin at gmail.com)
Date: Mon, 2 Nov 2015 05:45:09 -0800 (PST)
Subject: GoPiGo script
In-Reply-To: <AyJZx.1$Gy4.0@fe40.am1>
References: <d9hnjqF4lbuU1@mid.individual.net> <AyJZx.1$Gy4.0@fe40.am1>
Message-ID: <7bcb9d61-e610-47e3-9cba-35eba075e993@googlegroups.com>

On Monday, November 2, 2015 at 8:29:26 AM UTC-5, input/ld... at casema.nl wrote:
> I tried to use def loop(): now for to restart the script.
> but its only restart "fwd()" print ("forward 1x") and then stop.
> It does not look further for the if function.
> Is there another way to restart this script ?
> I also tried with (while True:) but that does nothing.
> 
> Thanks

<snip>

Try this: (hopefully the indentation is preserved)

from gopigo import *
from time import sleep

# Boolean variable for the "while" loop
KEEP_GOING = True

enable_servo()
mindist = 80
servo(90)

set_right_speed(150)
set_left_speed(105)

def MainLoop():
  # A check statement can be added to set KEEP_GOING to False
  # and allow the function to end
    while KEEP_GOING:
        mindist = 90
        server(90)
        fwd()
        print("forward1x")
        if mindist > us_dist(15):
            bwd()
            print("backward1x",us_dist(15)
            sleep(2)
            left_rot()
            print("left rot",us_dist(15))
            sleep(3)
            stop()
        if mindist < us_dist(15):
            fwd()
            print("forward2x",us_dist(15))
            time.sleep(2)
            stop()

# This is a simple check to determine if the script was run by itself
# or if it was imported by another script. If it was imported it will
# fail this check and not run the code but will allow access to the
# function defined above.
if __name__ == '__main__':
    MainLoop()


- Mike


From hakugin.gin at gmail.com  Mon Nov  2 08:49:27 2015
From: hakugin.gin at gmail.com (hakugin.gin at gmail.com)
Date: Mon, 2 Nov 2015 05:49:27 -0800 (PST)
Subject: GoPiGo script
In-Reply-To: <7bcb9d61-e610-47e3-9cba-35eba075e993@googlegroups.com>
References: <d9hnjqF4lbuU1@mid.individual.net> <AyJZx.1$Gy4.0@fe40.am1>
 <7bcb9d61-e610-47e3-9cba-35eba075e993@googlegroups.com>
Message-ID: <197fe872-0501-4ce8-a273-5220d4527c1f@googlegroups.com>

On Monday, November 2, 2015 at 8:45:35 AM UTC-5, hakug... at gmail.com wrote:
> On Monday, November 2, 2015 at 8:29:26 AM UTC-5, input/ld... at casema.nl wrote:
> > I tried to use def loop(): now for to restart the script.
> > but its only restart "fwd()" print ("forward 1x") and then stop.
> > It does not look further for the if function.
> > Is there another way to restart this script ?
> > I also tried with (while True:) but that does nothing.
> > 
> > Thanks
> 
> <snip>
> 

Ignore that last suggestion... between auto correct and other things there are some issues with it.

Try this instead:

from gopigo import *
from time import sleep

# Boolean variable for the "while" loop
KEEP_GOING = True

enable_servo()
mindist = 80
servo(90)

set_right_speed(150)
set_left_speed(105)

def MainLoop():
  # A check statement can be added to set KEEP_GOING to False
  # and allow the function to end
    while KEEP_GOING:
        fwd()
        print("forward1x")
        if mindist > us_dist(15):
            bwd()
            print("backward1x",us_dist(15)
            sleep(2)
            left_rot()
            print("left rot",us_dist(15))
            sleep(3)
            stop()
        if mindist < us_dist(15):
            fwd()
            print("forward2x",us_dist(15))
            time.sleep(2)
            stop()

# This is a simple check to determine if the script was run by itself
# or if it was imported by another script. If it was imported it will
# fail this check and not run the code but will allow access to the
# function defined above.
if __name__ == '__main__':
    MainLoop()

- Mike


From rosuav at gmail.com  Mon Nov  2 09:10:19 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 3 Nov 2015 01:10:19 +1100
Subject: Python 2 vs Python 3 for teaching
In-Reply-To: <c6405c34-43cc-417b-9027-12e3ac1bbfb5@googlegroups.com>
References: <mailman.7.1446371003.4463.python-list@python.org>
 <c6405c34-43cc-417b-9027-12e3ac1bbfb5@googlegroups.com>
Message-ID: <CAPTjJmqDPQfJoxsM0Obuo6p4qptZY=XCE_EzjCkERUEFQ0Pzgw@mail.gmail.com>

On Tue, Nov 3, 2015 at 12:15 AM, beliavsky--- via Python-list
<python-list at python.org> wrote:
> I think Python 2.x is still used more than Python 3.x in scientific computing. The Python books I have in this area, such as "Python for Finance: Analyze Big Financial Data" and "Python for Data Analysis", still use Python 2.x . An aspiring computational scientist, data scientist, or financial quant may still be better off learning Python 2.x but using print(x) rather than print x and doing other things to future-proof his code.
>

That doesn't mean that Python 3 *can't* be used. Far as I know, all
the key libraries (numpy, pandas, statsmodels, scipy) are available
for Python 3 as well. Recommending the use of Python 2 simply because
all the books you have teach Python 2 is a purely circular argument.

But yes. If you're going to use Py2, aim for the common subset. Good
Py2 code is a lot more similar to good Py3 code than an enumeration of
language-level differences would suggest.

ChrisA


From input/ldompeling at casema.nl  Mon Nov  2 09:28:17 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 02 Nov 2015 14:28:17 GMT
Subject: GoPiGo script
References: <197fe872-0501-4ce8-a273-5220d4527c1f@googlegroups.com>
Message-ID: <5qKZx.1282$u_1.105@fx05.am1>

He mike,

Thank you or making this script.
Only I get errors for sleep.
I also tried to change it to time.sleep() but that also gives errors.

File "test05.py", line 23
    sleep(2)
        ^
SyntaxError: invalid syntax
-------------------------------------------------------------------------------

In reply to "hakugin.gin at gmail.com" who wrote the following:

> On Monday, November 2, 2015 at 8:45:35 AM UTC-5, hakug... at gmail.com wrote:
> > On Monday, November 2, 2015 at 8:29:26 AM UTC-5, input/ld... at casema.nl 
> > wrote:
> > > I tried to use def loop(): now for to restart the script.
> > > but its only restart "fwd()" print ("forward 1x") and then stop.
> > > It does not look further for the if function.
> > > Is there another way to restart this script ?
> > > I also tried with (while True:) but that does nothing.
> > > 
> > > Thanks
> > 
> > <snip>
> > 
> 
> Ignore that last suggestion... between auto correct and other things there 
are
> some issues with it.
> 
> Try this instead:
> 
> from gopigo import *
> from time import sleep
> 
> # Boolean variable for the "while" loop
> KEEP_GOING = True
> 
> enable_servo()
> mindist = 80
> servo(90)
> 
> set_right_speed(150)
> set_left_speed(105)
> 
> def MainLoop():
>   # A check statement can be added to set KEEP_GOING to False
>   # and allow the function to end
>     while KEEP_GOING:
>         fwd()
>         print("forward1x")
>         if mindist > us_dist(15):
>             bwd()
>             print("backward1x",us_dist(15)
>             sleep(2)
>             left_rot()
>             print("left rot",us_dist(15))
>             sleep(3)
>             stop()
>         if mindist < us_dist(15):
>             fwd()
>             print("forward2x",us_dist(15))
>             time.sleep(2)
>             stop()
> 
> # This is a simple check to determine if the script was run by itself
> # or if it was imported by another script. If it was imported it will
> # fail this check and not run the code but will allow access to the
> # function defined above.
> if __name__ == '__main__':
>     MainLoop()
> 
> - Mike




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From arimfrexdrapuse at gmail.com  Mon Nov  2 09:28:37 2015
From: arimfrexdrapuse at gmail.com (Gabe Clark)
Date: Mon, 2 Nov 2015 09:28:37 -0500
Subject: help
Message-ID: <CAFuR03m2KrG5ZsYU4U5y754ivh5_ucf1Azo5x8K+ZnTrXA4khQ@mail.gmail.com>

i am currently running python 3.5 in my programming class and when ever i
go to open one of my saved files or a file saved by some one else this new
tab pops up and says modify, repair, or uninstall i have uninstalled and
repaired it multiple times to no success please help


From nulla.epistola at web.de  Mon Nov  2 09:32:43 2015
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Mon, 2 Nov 2015 15:32:43 +0100
Subject: same problem even after repair
In-Reply-To: <563758A8.7010207@comcast.net>
References: <563758A8.7010207@comcast.net>
Message-ID: <5637740B.6070104@web.de>

Am 02.11.2015 um 13:35 schrieb Daniel Joffe:
>
Didn't you see the answers to your first posting? All of them earlier 
than this.

Sibylle




From nulla.epistola at web.de  Mon Nov  2 09:32:43 2015
From: nulla.epistola at web.de (Sibylle Koczian)
Date: Mon, 2 Nov 2015 15:32:43 +0100
Subject: same problem even after repair
In-Reply-To: <563758A8.7010207@comcast.net>
References: <563758A8.7010207@comcast.net>
Message-ID: <5637740B.6070104@web.de>

Am 02.11.2015 um 13:35 schrieb Daniel Joffe:
>
Didn't you see the answers to your first posting? All of them earlier 
than this.

Sibylle



From input/ldompeling at casema.nl  Mon Nov  2 09:32:57 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 02 Nov 2015 14:32:57 GMT
Subject: GoPiGo script
References: <mailman.64.1446473424.4463.python-list@python.org>
Message-ID: <tuKZx.1283$u_1.517@fx05.am1>

Thank you for the explanation for it.
I must tell you that  i yust beginning with python.
I bought the book beginning programming with python.









In reply to "Dennis Lee Bieber" who wrote the following:

> On Mon, 02 Nov 2015 13:29:04 GMT, input/ldompeling at casema.nl declaimed the
> following:
> 
> > I tried to use def loop(): now for to restart the script.
> > but its only restart "fwd()" print ("forward 1x") and then stop.
> 
> > def loop():
> >    fwd()
> >    print ("forward 1x")
> >    time.sleep(2)
> >    stop()
> > 
> > if mindist > us_dist(15):
> 
>  Which is exactly what you told it to do. You have defined a function
> containing four statements: fwd(), print(), sleep(), and stop(); after
> executing the stop the function will return to where it was called -- the
> end of your program.
> 
>  All of your"if" statements will be executed after "loop" is defined
> (but not executed) and before the call to "loop" at the bottom. They are
> NOT part of "loop". Please reread the Python language reference manual,
> focusing on the part that describes indentation and block structuring.
> 
> 
> > loop()
> > 
> 
>  Also, just calling something "loop" does not make it a loop. This
> function will be called just one time and then the program will exit.
> --
>  Wulfraed                 Dennis Lee Bieber         AF6VN
>     wlfraed at ix.netcom.com    HTTP://wlfraed.home.netcom.com/




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From ian.g.kelly at gmail.com  Mon Nov  2 09:49:23 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 2 Nov 2015 07:49:23 -0700
Subject: help
In-Reply-To: <CAFuR03m2KrG5ZsYU4U5y754ivh5_ucf1Azo5x8K+ZnTrXA4khQ@mail.gmail.com>
References: <CAFuR03m2KrG5ZsYU4U5y754ivh5_ucf1Azo5x8K+ZnTrXA4khQ@mail.gmail.com>
Message-ID: <CALwzidnNMVdTdU_NXpS9MPOSfcVcZ4u5-uoWknHQ8VtWQRqq0g@mail.gmail.com>

On Nov 2, 2015 7:31 AM, "Gabe Clark" <arimfrexdrapuse at gmail.com> wrote:
>
> i am currently running python 3.5 in my programming class and when ever i
> go to open one of my saved files or a file saved by some one else this new
> tab pops up and says modify, repair, or uninstall i have uninstalled and
> repaired it multiple times to no success please help

Check the Windows file association for .py files (you are saving your files
with the .py extension, right?). From the description it sounds like .py
has somehow become associated with the Python installer rather than the
Python interpreter.

If you're familiar with the command line, you can run the script by running
Python specifically and passing the script as a command-line argument.


From hakugin.gin at gmail.com  Mon Nov  2 10:19:09 2015
From: hakugin.gin at gmail.com (hakugin.gin at gmail.com)
Date: Mon, 2 Nov 2015 07:19:09 -0800 (PST)
Subject: GoPiGo script
In-Reply-To: <5qKZx.1282$u_1.105@fx05.am1>
References: <197fe872-0501-4ce8-a273-5220d4527c1f@googlegroups.com>
 <5qKZx.1282$u_1.105@fx05.am1>
Message-ID: <e4e11fd6-01b2-4b86-9fc9-13c50b25342f@googlegroups.com>

On Monday, November 2, 2015 at 9:28:35 AM UTC-5, input/ld... at casema.nl wrote:
> He mike,
> 
> Thank you or making this script.
> Only I get errors for sleep.
> I also tried to change it to time.sleep() but that also gives errors.
> 
> File "test05.py", line 23
>     sleep(2)
>         ^
> SyntaxError: invalid syntax
> -------------------------------------------------------------------------------
> 

And this is why I shouldn't code while tired hahaha...

I reviewed the code I submitted and found a couple of other errors. If you are changing the "sleep()" lines to "time.sleep()" you will need to change the line "from time import sleep" to "import time", otherwise you will most likely encounter something like:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'time' is not defined

Since you are just beginning with Python I would suggest reading various entry level books such as Python 101 by Mike Driscoll, which I have read and own. I am not Mike Driscoll, but his book and blog, http://www.blog.pythonlibrary.org/ have been extremely helpful. There are MANY resources available for learning the Python programming language out there, including https://wiki.python.org/moin/BeginnersGuide


From python at mrabarnett.plus.com  Mon Nov  2 10:21:16 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 2 Nov 2015 15:21:16 +0000
Subject: GoPiGo script
In-Reply-To: <5qKZx.1282$u_1.105@fx05.am1>
References: <197fe872-0501-4ce8-a273-5220d4527c1f@googlegroups.com>
 <5qKZx.1282$u_1.105@fx05.am1>
Message-ID: <56377F6C.1040309@mrabarnett.plus.com>

On 2015-11-02 14:28, input/ldompeling at casema.nl wrote:
> He mike,
>
> Thank you or making this script.
> Only I get errors for sleep.
> I also tried to change it to time.sleep() but that also gives errors.
>
> File "test05.py", line 23
>      sleep(2)
>          ^
> SyntaxError: invalid syntax
> -------------------------------------------------------------------------------
>
The previous line is missing a ")"; it should end with two of them, not
just one.

> In reply to "hakugin.gin at gmail.com" who wrote the following:
>
>> On Monday, November 2, 2015 at 8:45:35 AM UTC-5, hakug... at gmail.com wrote:
>> > On Monday, November 2, 2015 at 8:29:26 AM UTC-5, input/ld... at casema.nl
>> > wrote:
>> > > I tried to use def loop(): now for to restart the script.
>> > > but its only restart "fwd()" print ("forward 1x") and then stop.
>> > > It does not look further for the if function.
>> > > Is there another way to restart this script ?
>> > > I also tried with (while True:) but that does nothing.
>> > >
>> > > Thanks
>> >
>> > <snip>
>> >
>>
>> Ignore that last suggestion... between auto correct and other things there
> are
>> some issues with it.
>>
>> Try this instead:
>>
>> from gopigo import *
>> from time import sleep
>>
>> # Boolean variable for the "while" loop
>> KEEP_GOING = True
>>
>> enable_servo()
>> mindist = 80
>> servo(90)
>>
>> set_right_speed(150)
>> set_left_speed(105)
>>
>> def MainLoop():
>>   # A check statement can be added to set KEEP_GOING to False
>>   # and allow the function to end
>>     while KEEP_GOING:
>>         fwd()
>>         print("forward1x")
>>         if mindist > us_dist(15):
>>             bwd()
>>             print("backward1x",us_dist(15)
>>             sleep(2)
>>             left_rot()
>>             print("left rot",us_dist(15))
>>             sleep(3)
>>             stop()
>>         if mindist < us_dist(15):
>>             fwd()
>>             print("forward2x",us_dist(15))
>>             time.sleep(2)
>>             stop()
>>
>> # This is a simple check to determine if the script was run by itself
>> # or if it was imported by another script. If it was imported it will
>> # fail this check and not run the code but will allow access to the
>> # function defined above.
>> if __name__ == '__main__':
>>     MainLoop()
>>



From hakugin.gin at gmail.com  Mon Nov  2 10:30:48 2015
From: hakugin.gin at gmail.com (hakugin.gin at gmail.com)
Date: Mon, 2 Nov 2015 07:30:48 -0800 (PST)
Subject: GoPiGo script
In-Reply-To: <mailman.69.1446477686.4463.python-list@python.org>
References: <197fe872-0501-4ce8-a273-5220d4527c1f@googlegroups.com>
 <5qKZx.1282$u_1.105@fx05.am1>
 <mailman.69.1446477686.4463.python-list@python.org>
Message-ID: <5fb9577c-175f-402a-9307-3d9e7f448cc7@googlegroups.com>

On Monday, November 2, 2015 at 10:21:46 AM UTC-5, MRAB wrote:
> On 2015-11-02 14:28, input/ldom... at casema.nl wrote:
> > He mike,
> >
> > Thank you or making this script.
> > Only I get errors for sleep.
> > I also tried to change it to time.sleep() but that also gives errors.
> >
> > File "test05.py", line 23
> >      sleep(2)
> >          ^
> > SyntaxError: invalid syntax
> > -------------------------------------------------------------------------------
> >
> The previous line is missing a ")"; it should end with two of them, not
> just one.
> 

Yep, I shouldn't code while tired... I also forgot to change line 31 from "time.sleep(2)" to "sleep(2)".

> > In reply to "haku... at gmail.com" who wrote the following:
> >
> >> On Monday, November 2, 2015 at 8:45:35 AM UTC-5, hakug... at gmail.com wrote:
> >> > On Monday, November 2, 2015 at 8:29:26 AM UTC-5, input/ld... at casema.nl
> >> > wrote:
> >> > > I tried to use def loop(): now for to restart the script.
> >> > > but its only restart "fwd()" print ("forward 1x") and then stop.
> >> > > It does not look further for the if function.
> >> > > Is there another way to restart this script ?
> >> > > I also tried with (while True:) but that does nothing.
> >> > >
> >> > > Thanks
> >> >
> >> > <snip>
> >> >
> >>
> >> Ignore that last suggestion... between auto correct and other things there
> > are
> >> some issues with it.
> >>
> >> Try this instead:
> >>
> >> from gopigo import *
> >> from time import sleep
> >>
> >> # Boolean variable for the "while" loop
> >> KEEP_GOING = True
> >>
> >> enable_servo()
> >> mindist = 80
> >> servo(90)
> >>
> >> set_right_speed(150)
> >> set_left_speed(105)
> >>
> >> def MainLoop():
> >>   # A check statement can be added to set KEEP_GOING to False
> >>   # and allow the function to end
> >>     while KEEP_GOING:
> >>         fwd()
> >>         print("forward1x")
> >>         if mindist > us_dist(15):
> >>             bwd()
> >>             print("backward1x",us_dist(15)
> >>             sleep(2)
> >>             left_rot()
> >>             print("left rot",us_dist(15))
> >>             sleep(3)
> >>             stop()
> >>         if mindist < us_dist(15):
> >>             fwd()
> >>             print("forward2x",us_dist(15))
> >>             time.sleep(2)
> >>             stop()
> >>
> >> # This is a simple check to determine if the script was run by itself
> >> # or if it was imported by another script. If it was imported it will
> >> # fail this check and not run the code but will allow access to the
> >> # function defined above.
> >> if __name__ == '__main__':
> >>     MainLoop()
> >>



From RobinsW1 at sutterhealth.org  Mon Nov  2 10:52:07 2015
From: RobinsW1 at sutterhealth.org (Robinson, Wendy)
Date: Mon, 2 Nov 2015 07:52:07 -0800
Subject: Puzzled
In-Reply-To: <201511011020.tA1AKYAM004182@fido.openend.se>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
Message-ID: <4CFEDC132D44AC49BA0E91FBEB947119084A742DCC@DCBL123VX.root.sutterhealth.org>

[cid:image001.png at 01D11543.5ED11D50]



Wendy Robinson

Audit Analyst

(916) 566-4994 phone







NOTICE OF CONFIDENTIALITY: This email is for the sole use of the intended recipient and may contain material that is confidential and protected by state and federal regulations.  If you are not the intended recipient please immediately delete it and contact the sender.



-----Original Message-----
From: Laura Creighton [mailto:lac at openend.se]
Sent: Sunday, November 01, 2015 2:21 AM
To: Robinson, Wendy
Cc: 'python-list at python.org'; lac at openend.se
Subject: Re: Puzzled



In a message of Fri, 30 Oct 2015 09:20:23 -0700, "Robinson, Wendy" writes:

>Hi there,

>I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.

>This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.

>

>I tried running the Repair installation, but that did not help.

>

>Any suggestions?

>

>Thank you

>

>Wendy Robinson

>Audit Analyst

>(916) 566-4994 phone



Paste in the Full traceback you get from the console.

Also check and see that the console is actually running the 3.5 you installed, and not some other python, like 2.7 you might have lying around.



Laura


From rurpy at yahoo.com  Mon Nov  2 10:53:22 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Mon, 2 Nov 2015 07:53:22 -0800 (PST)
Subject: installer user interface glitch ?
In-Reply-To: <mailman.36.1446414523.4463.python-list@python.org>
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
 <mailman.31.1446396218.4463.python-list@python.org>
 <641afbd8-b0b3-4d6b-969f-13cf19c25043@googlegroups.com>
 <mailman.36.1446414523.4463.python-list@python.org>
Message-ID: <95f13f37-52ec-4aaa-9ece-4e8057148217@googlegroups.com>

On Sunday, November 1, 2015 at 2:48:58 PM UTC-7, Laura Creighton wrote:
> Actually, adding the XP - do not look here --
> message for several webpages has been on the pydotorg
> todo list for more than a week now.
> 
> Not sure why it hasn't happened.
> 
> Thank you for the reminder.

You're welcome.  And thanks for the reasonable response.  Everytime
I post to this list it is like stepping into Alice's Wonderland so
it is a nice change.


From teamprimalforce at gmail.com  Mon Nov  2 13:35:55 2015
From: teamprimalforce at gmail.com (Lee Bradley)
Date: Mon, 2 Nov 2015 10:35:55 -0800 (PST)
Subject: need help understanding a python program
Message-ID: <f25cc66a-3003-41cb-8c47-bbece515c275@googlegroups.com>

http://pastebin.com/ndDYjYe1

The above link takes you to a very interesting way of solving the classic game of Bulls and Cows. It uses an entropy-based decision algorithm. I realize this is asking a lot but I am not yet proficient enough in python to follow some of the methods.

There is a fair amount on the internet on both the game and on entropy-based machine learning. I will provide further information if anyone is interested.

For now I am looking for someone who can dig into this code and explain what's going on. I understand a lot of it but not enough to really *get it*.


From ben+python at benfinney.id.au  Mon Nov  2 13:45:15 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 03 Nov 2015 05:45:15 +1100
Subject: need help understanding a python program
References: <f25cc66a-3003-41cb-8c47-bbece515c275@googlegroups.com>
Message-ID: <85vb9kkzpg.fsf@benfinney.id.au>

Lee Bradley <teamprimalforce at gmail.com> writes:

> http://pastebin.com/ndDYjYe1

We much prefer to discuss code in the context of plain text messages
right here, because this forum is archived longer than the expected
lifetime of content hosted on other services.

> For now I am looking for someone who can dig into this code and
> explain what's going on. I understand a lot of it but not enough to
> really *get it*.

Could you discuss your own impressions of it so far, with (parts of) the
code pasted here as plain text for context of your commentary?

-- 
 \       Moriarty: ?Forty thousand million billion dollars? That money |
  `\            must be worth a fortune!? ?The Goon Show, _The Sale of |
_o__)                                                       Manhattan_ |
Ben Finney



From zljubisic at gmail.com  Mon Nov  2 14:24:36 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 2 Nov 2015 11:24:36 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
Message-ID: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>

Let's say that I have the following simple function:

def get_html(url):

    wpage = requests.get(url)
    
    return wpage.text

How to handle exceptions properly that can arise during execution of the requests.get(url)?

If I call this function with

try:
    html = get_html('www.abc.com/index.html')
except ConnectionError:
        service_exception
else:
    continue_with_the_code

and ConnectionError exception happens I can handle the exception with service_exception part of the code.

I could also put some try/except block in get_html function, but the only purpose why should I do it,  is to log the url and re rise the error. Is there any other reason why should I do this?
 
def get_html(url):

    try:
        wpage = requests.get(url)
    except ConnectionError:
        flog('warning', 'ConnectionError exception', log_except=True)
        raise

    return 

Anyway, whenever I am calling the get_html function I should put it in the try/except block and handle all exceptions.
Now which exceptions? Can I know them in advance or I should wait for one to happened and then put it in caller except block?

Let's say that I have called get_html function hundred times in try/except block with ConnectionError part, and now I found a new exception that can happen during execution of the requests.get(url) command. What should I do now?
Should I put the same except block that handles that new exception in every and each of these hundred calls? 

I could also handle all exceptions in get_html function, and in case that I am not able to get the html, I can return None. 

def get_html(url):

    try:
        wpage = requests.get(url)
    except ConnectionError:
        flog('warning', 'ConnectionError exception', log_except=True)
        raise
    except Exception as e:
        flog("warning", "{0}   [wpage = requests.get(url) {1}]".format(e, url), log_except=True)
        raise
    else:

        if wpage.status_code == requests.codes.ok:
            flog('debug', 'wpage.status_code = %s' % wpage.status_code)
            html = wpage.text
        else:
            flog('debug', 'url = %s' % url)
            html = None

    return html


Now caller should only check if function has returned something other than None. Caller doesn't need try/except block anymore. Something like this:

if get_html('www.abc.com/index.html') is not None:
    I_am_sure_that_html_has_been_downloaded_correctly


Now if I want to catch a new exception, I can catch it in get_html function, which is the only change in the program.

I have read some articles that returning None is not a good approach, so I am confused.

How to handle exceptions properly in a pythonic way?

Regards.


From robin.koch at t-online.de  Mon Nov  2 14:31:29 2015
From: robin.koch at t-online.de (Robin Koch)
Date: Mon, 2 Nov 2015 20:31:29 +0100
Subject: GoPiGo script
In-Reply-To: <tuKZx.1283$u_1.517@fx05.am1>
References: <mailman.64.1446473424.4463.python-list@python.org>
 <tuKZx.1283$u_1.517@fx05.am1>
Message-ID: <n18dmg$hvo$1@news.albasani.net>

Am 02.11.2015 um 15:32 schrieb input/ldompeling at casema.nl:

> Thank you for the explanation for it.
> I must tell you that  i yust beginning with python.
> I bought the book beginning programming with python.

Have you programming experience with other languages?

Well, the very first thing you should have learned is the basic syntax 
of Python. (That's how a program has to be written to work properly.)

And one of those first things is that python code is structured not by 
braces (like many other programming languages), but by intendation (as 
mentioned by others before).

That means that everything "depending" of a line somehow has to be 
intended deeper than that line.

Those lines are typically lines starting with "if", "for", "while", 
"def" or other keywords and end with a colon.

In your code the ifs and fors (and the following lines) are correctly 
intended. But you are using the "while" and "def" kind of wrong.

Let me give an example (note that the line numbers are only for this 
posting to prevent funny formating business and to talk about the single 
lines!):

01 for i in [1,2,3]:
02     print('A')
03     print('B')
04 print('C')

The first line (01) starts a loop. (Starting with a for, ending with a 
colon.) For every entry in the given list "something" is supposed to be 
repeated. But what is repeated and what isn't?

Easy: All following *intended* lines (02-03) are repeated.
Line 04 isn't intended and marks the point where the loop ends.

The output of the above is:

A
B
A
B
A
B
C


If we change the code just a tiny bit:

01 for i in [1,2,3]:
02     print('A')
03 print('B')
04 print('C')

(Notice, that the only change is the removed whitespace in line 03.)

only line 02 is repeated:

A
A
A
B
C


That works also for if and while:

01 if False:
02     print("This isn't printed.")
03     print("This neigther.")
03 print("But this is!")

01 c = 1
02 while c < 10:
03     print(c)
04     c = c*2
05 print("done")

prints

1
2
4
8
done


And of course those are mixable:

01 for a in [3,5,7]:
02    b = 1
03    while a*b < 10:
04	if a*b % 2 != 0:
05            print(a*b)
06        b = b+1
07    print("Next a")
08 print("done")

prints:

3
9
Next a
5
Next a
7
Next a
done


And this is where your problems seems to be.

You start with

"while True:"

which does start an endless loop.

But: As explained it only repeats the lines theat follow and are intended!

In your original post the next line isn't intended at all, which is 
considered an error.
In your second attempt you intended only the first 5 lines. So those 
(and only those) are repeated.

The next line ("if mindist > us_dist(15):") wasn't intended and 
therefore *not* repeated.

If you just learning programming with Python you migth want to start 
with smaller examples to understand the syntax better.
Do you understand what the script is supposed to do in every line?

-- 
Robin Koch


From gordon at panix.com  Mon Nov  2 15:05:36 2015
From: gordon at panix.com (John Gordon)
Date: Mon, 2 Nov 2015 20:05:36 +0000 (UTC)
Subject: How to handle exceptions properly in a pythonic way?
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
Message-ID: <n18fmg$oj6$1@reader1.panix.com>

In <4b303213-62e2-42d4-b2f6-4fc1f6025944 at googlegroups.com> zljubisic at gmail.com writes:

> Let's say that I have the following simple function:

> def get_html(url):

>     wpage = requests.get(url)
>     
>     return wpage.text

> How to handle exceptions properly that can arise during execution of the
> requests.get(url)?

The best way is probably to do nothing at all, and let the caller handle
any exceptions.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From ian.g.kelly at gmail.com  Mon Nov  2 15:58:39 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 2 Nov 2015 13:58:39 -0700
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
Message-ID: <CALwzid=CGd+LDSY+1C-0dtP0q+cbEb3kA2NPCCVvsZSL5tR+sg@mail.gmail.com>

On Mon, Nov 2, 2015 at 12:24 PM,  <zljubisic at gmail.com> wrote:
> I have read some articles that returning None is not a good approach, so I am confused.
>
> How to handle exceptions properly in a pythonic way?

I'm having a hard time understanding what question you're asking. You
have a lot of discussion about where to handle exceptions, but the
examples that you show are of logging the the exception and re-raising
it, which is a good practice but distinct from handling the exception.

Then you seem to be asking about the practice of returning None as an
alternative to propagating the exception, but the example you show
only returns None in a case where no exception was raised in the first
place.

None is arguably reasonable to return when it makes sense as a
non-exceptional value in the context. For example, if you're looking
up a policy that may or may not exist, then your get_policy function
might return None to indicate no value. If get_policy fails because of
an RPC timeout however, then it needs to raise an exception rather
than possibly incorrectly returning "no policy".

In comparison, if you're returning something that should always have a
value, then you should never return None. In such a case, None would
indicate that something went wrong, but it lacks any information about
*what* went wrong. An exception, on the other hand, is ideal for
carrying that sort of information. Returning None in such a scenario
is also risky in that the caller may not be expecting None and may try
to treat it as a normal value. In some cases this may even appear to
work until something breaks in a completely different part of the
code.

In the example given, the case where None is returned is clearly an
exceptional case (non-success) even though no exception was raised by
requests.get. You should raise an exception there instead of returning
None to allow the caller better control over the situation.


From orgnut at yahoo.com  Mon Nov  2 16:06:43 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Mon, 2 Nov 2015 13:06:43 -0800
Subject: GoPiGo script
In-Reply-To: <n18dmg$hvo$1@news.albasani.net>
References: <mailman.64.1446473424.4463.python-list@python.org>
 <tuKZx.1283$u_1.517@fx05.am1> <n18dmg$hvo$1@news.albasani.net>
Message-ID: <GIqdnXbZo7v1TarLnZ2dnUU7-Y_OydjZ@giganews.com>

On 11/02/2015 11:31 AM, Robin Koch wrote:
> Am 02.11.2015 um 15:32 schrieb input/ldompeling at casema.nl:
>
>> Thank you for the explanation for it.
>> I must tell you that  i yust beginning with python.
>> I bought the book beginning programming with python.
>
> Have you programming experience with other languages?
>
> Well, the very first thing you should have learned is the basic syntax of Python. (That's how a
> program has to be written to work properly.)
>
> And one of those first things is that python code is structured not by braces (like many other
> programming languages), but by intendation (as mentioned by others before).
                                  ^^^^^^^^^^^

[snip a lot of text, also using the word intend...]

The word you want is indent not intend.
Intend means something entirely different,
and is not a Python term.

      -=- Larry -=-



From lorenzofsutton at gmail.com  Mon Nov  2 18:29:51 2015
From: lorenzofsutton at gmail.com (Lorenzo Sutton)
Date: Tue, 3 Nov 2015 00:29:51 +0100
Subject: Detection of a specific sound
In-Reply-To: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
Message-ID: <5637F1EF.2030505@gmail.com>

On 26/10/15 01:17, Montana Burr wrote:
> I'm looking for a library that will allow Python to listen for the
> shriek of a smoke alarm. Once it detects this shriek, it is to notify
> someone. Ideally, specificity can be adjusted for the user's
> environment. For example, I expect to need moderate specificity as I
> live in a quiet neighborhood, but an apartment dweller might need more.
>
> I'm thinking of recording a smoke alarm and having the program try to
> find the recorded sound in the stream from the microphone.
>
> Any help is greatly appreciated!
>

It would really be helpful if you could explain the (hardware) setting 
in more detail.
When you say "Python to listen" I assume you mean a microphone connected 
to a computer where your python programme will be running.

How many smoke allarms and in what radius should be detected? Or is it 
only a specific one?

This could range from a simple programme triggered by an amplitude 
change (e.g. a piezo attached to the single alarm in question) to a 
complex audio fingerprinting one...

Lorenzo.


From robin.koch at t-online.de  Mon Nov  2 19:45:23 2015
From: robin.koch at t-online.de (Robin Koch)
Date: Tue, 3 Nov 2015 01:45:23 +0100
Subject: GoPiGo script
In-Reply-To: <GIqdnXbZo7v1TarLnZ2dnUU7-Y_OydjZ@giganews.com>
References: <mailman.64.1446473424.4463.python-list@python.org>
 <tuKZx.1283$u_1.517@fx05.am1> <n18dmg$hvo$1@news.albasani.net>
 <GIqdnXbZo7v1TarLnZ2dnUU7-Y_OydjZ@giganews.com>
Message-ID: <n19033$jkj$1@news.albasani.net>

Am 02.11.2015 um 22:06 schrieb Larry Hudson:

> [snip a lot of text, also using the word intend...]
>
> The word you want is indent not intend.

Oops. Of course you are right.
You might have noticed, english isn't my native language.
Not an excuse, but an explanation. ;-)

I can only hope, that Loek does understand what I meant.

> Intend means something entirely different,
> and is not a Python term.

Yes, I know the difference. I just didn't pay enough attention to it.

Ironically enough I wrote actually another post about Android-intends 
earlier.

-- 
Robin Koch


From Seymore4Head at Hotmail.invalid  Mon Nov  2 20:09:02 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Mon, 02 Nov 2015 20:09:02 -0500
Subject: Regular expressions
Message-ID: <662g3blobme52hfoududj27err185v2npm@4ax.com>

How do I make a regular expression that returns true if the end of the
line is an asterisk



From python at mrabarnett.plus.com  Mon Nov  2 20:19:34 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 3 Nov 2015 01:19:34 +0000
Subject: Regular expressions
In-Reply-To: <662g3blobme52hfoududj27err185v2npm@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
Message-ID: <56380BA6.20500@mrabarnett.plus.com>

On 2015-11-03 01:09, Seymore4Head wrote:
> How do I make a regular expression that returns true if the end of the
> line is an asterisk
>
To match an asterisk: \*

To match the end of a line: $

To match an asterisk at the end of a line: \*$



From python.list at tim.thechases.com  Mon Nov  2 21:42:37 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 2 Nov 2015 20:42:37 -0600
Subject: Regular expressions
In-Reply-To: <662g3blobme52hfoududj27err185v2npm@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
Message-ID: <20151102204237.6a78abdf@bigbox.christie.dr>

On 2015-11-02 20:09, Seymore4Head wrote:
> How do I make a regular expression that returns true if the end of
> the line is an asterisk

Why use a regular expression?

  if line[-1] == '*':
    yep(line)
  else:
    nope(line)

-tkc





From Seymore4Head at Hotmail.invalid  Mon Nov  2 22:17:49 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Mon, 02 Nov 2015 22:17:49 -0500
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
Message-ID: <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>

On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
<python.list at tim.thechases.com> wrote:

>On 2015-11-02 20:09, Seymore4Head wrote:
>> How do I make a regular expression that returns true if the end of
>> the line is an asterisk
>
>Why use a regular expression?
>
>  if line[-1] == '*':
>    yep(line)
>  else:
>    nope(line)
>
>-tkc
>
>
Because that is the part of Python I am trying to learn at the moment.
Thanks


From Seymore4Head at Hotmail.invalid  Mon Nov  2 22:17:59 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Mon, 02 Nov 2015 22:17:59 -0500
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.76.1446513578.4463.python-list@python.org>
Message-ID: <1r9g3bd89q1mp36l7bioasgmsrhsb8c7fg@4ax.com>

On Tue, 3 Nov 2015 01:19:34 +0000, MRAB <python at mrabarnett.plus.com>
wrote:

>On 2015-11-03 01:09, Seymore4Head wrote:
>> How do I make a regular expression that returns true if the end of the
>> line is an asterisk
>>
>To match an asterisk: \*
>
>To match the end of a line: $
>
>To match an asterisk at the end of a line: \*$

Thanks


From torriem at gmail.com  Mon Nov  2 22:49:03 2015
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 02 Nov 2015 20:49:03 -0700
Subject: Detection of a specific sound
In-Reply-To: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
Message-ID: <56382EAF.2000407@gmail.com>

On 10/25/2015 06:17 PM, Montana Burr wrote:
> I'm looking for a library that will allow Python to listen for the shriek
> of a smoke alarm. Once it detects this shriek, it is to notify someone.
> Ideally, specificity can be adjusted for the user's environment. For
> example, I expect to need moderate specificity as I live in a quiet
> neighborhood, but an apartment dweller might need more.
> 
> I'm thinking of recording a smoke alarm and having the program try to find
> the recorded sound in the stream from the microphone.
> 
> Any help is greatly appreciated!

At this point, from what you say, your problem is not a python one. It's
a more general problem that you have to tackle.  In other words how are
you going to identify this one sound amongst background noise?  Once you
know that, then you can apply Python to the problem.

I suggest you spend some time exploring how you would actually go about
recognizing a particular sound algorithmically.  Relevant tops of
research include: digital signal processing and fourier analysis.

A quick google search reveals some info that may point you in the right
direction:

https://blog.adafruit.com/2015/01/12/think-dsp-introduction-to-signal-processing-using-python/
http://samcarcagno.altervista.org/blog/basic-sound-processing-python/

I know very little about the subject, but if it were me, my naive
approach would be to do fourier analysis on the sound you are trying to
identify to pick out the sound's fingerprint (certain component
waveforms that stand out), and then do the same analysis on your audio
stream, looking for this footprint.


From torriem at gmail.com  Mon Nov  2 22:51:15 2015
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 02 Nov 2015 20:51:15 -0700
Subject: Regular expressions
In-Reply-To: <20151102204237.6a78abdf@bigbox.christie.dr>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
Message-ID: <56382F33.8050905@gmail.com>

On 11/02/2015 07:42 PM, Tim Chase wrote:
> On 2015-11-02 20:09, Seymore4Head wrote:
>> How do I make a regular expression that returns true if the end of
>> the line is an asterisk
> 
> Why use a regular expression?
> 
>   if line[-1] == '*':
>     yep(line)
>   else:
>     nope(line)

Indeed, sometimes Jamie Zawinski's is often quite appropriate:

    Some people, when confronted with a problem, think "I know, I'll use
regular expressions." Now they have two problems.




From joel.goldstick at gmail.com  Mon Nov  2 22:58:22 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Mon, 2 Nov 2015 22:58:22 -0500
Subject: Regular expressions
In-Reply-To: <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
Message-ID: <CAPM-O+xyqNV6bs6UNUJzpFbLdhS5fY+ep-BLgzBi7xuW33Kavg@mail.gmail.com>

On Mon, Nov 2, 2015 at 10:17 PM, Seymore4Head <Seymore4Head at hotmail.invalid>
wrote:

> On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
> <python.list at tim.thechases.com> wrote:
>
> >On 2015-11-02 20:09, Seymore4Head wrote:
> >> How do I make a regular expression that returns true if the end of
> >> the line is an asterisk
> >
> >Why use a regular expression?
> >
> >  if line[-1] == '*':
> >    yep(line)
> >  else:
> >    nope(line)
> >
> >-tkc
> >
> >
> Because that is the part of Python I am trying to learn at the moment.
> Thanks
> --
> https://mail.python.org/mailman/listinfo/python-list
>

My completely unsolicited advice is that regular expressions shouldn't be
very high on the list of things to learn.  They are very useful, and very
tricky and prone many problems that can and should be learned to be
resolved with much simpler methods.  If you really want to learn regular
expressions, that's great but the problem you posed is not one for which
they are the best solution.  Remember simpler is better than complex.

-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From rurpy at yahoo.com  Mon Nov  2 23:23:15 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Mon, 2 Nov 2015 20:23:15 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.2.1446522680.8789.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <mailman.2.1446522680.8789.python-list@python.org>
Message-ID: <0cb3abb6-ec1e-4357-ab0f-b018d0c688fa@googlegroups.com>

On 11/02/2015 08:51 PM, Michael Torrie wrote:
>[...]
> Indeed, sometimes Jamie Zawinski's is often quite appropriate:
> 
>     Some people, when confronted with a problem, think "I know, I'll use
> regular expressions." Now they have two problems.

Or its sometimes heard paraphrase:
  Some people, when confronted with a problem, think "I know, I'll use
  Python." Now they have two problems
The point being it's a cute and memorable aphorism but not very meaningful
because it can be applied to anything one wishes to denigrate.

Of course there are people who misuse regexes. But I am quite sure,
especially in the Python community, there are just as many who fail to
use them when they are appropriate which is just as bad.


From rurpy at yahoo.com  Mon Nov  2 23:23:48 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Mon, 2 Nov 2015 20:23:48 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.3.1446523111.8789.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
Message-ID: <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>

On Monday, November 2, 2015 at 8:58:45 PM UTC-7, Joel Goldstick wrote:
> On Mon, Nov 2, 2015 at 10:17 PM, Seymore4Head <Seymore4Head at hotmail.invalid>
> wrote:
> 
> > On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
> > <python.list at tim.thechases.com> wrote:
> >
> > >On 2015-11-02 20:09, Seymore4Head wrote:
> > >> How do I make a regular expression that returns true if the end of
> > >> the line is an asterisk
> > >
> > >Why use a regular expression?
> > >
> > >  if line[-1] == '*':
> > >    yep(line)
> > >  else:
> > >    nope(line)
> > >
> > >-tkc
> > >
> > >
> > Because that is the part of Python I am trying to learn at the moment.
> > Thanks
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> >
> 
> My completely unsolicited advice is that regular expressions shouldn't be
> very high on the list of things to learn.  They are very useful, and very
> tricky and prone many problems that can and should be learned to be
> resolved with much simpler methods.  If you really want to learn regular
> expressions, that's great but the problem you posed is not one for which
> they are the best solution.  Remember simpler is better than complex.

Regular expressions should be learned by every programmer or by anyone
who wants to use computers as a tool.  They are a fundamental part of
computer science and are used in all sorts of matching and searching 
from compilers down to your work-a-day text editor.

Not knowing how to use them is like an auto mechanic not knowing how to 
use a socket wrench.


From torriem at gmail.com  Mon Nov  2 23:33:50 2015
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 02 Nov 2015 21:33:50 -0700
Subject: Regular expressions
In-Reply-To: <0cb3abb6-ec1e-4357-ab0f-b018d0c688fa@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <mailman.2.1446522680.8789.python-list@python.org>
 <0cb3abb6-ec1e-4357-ab0f-b018d0c688fa@googlegroups.com>
Message-ID: <5638392E.8080308@gmail.com>

On 11/02/2015 09:23 PM, rurpy--- via Python-list wrote:
> On 11/02/2015 08:51 PM, Michael Torrie wrote:
>> [...]
>> Indeed, sometimes Jamie Zawinski's is often quite appropriate:
>>
>>     Some people, when confronted with a problem, think "I know, I'll use
>> regular expressions." Now they have two problems.
> 
> Or its sometimes heard paraphrase:
>   Some people, when confronted with a problem, think "I know, I'll use
>   Python." Now they have two problems
> The point being it's a cute and memorable aphorism but not very meaningful
> because it can be applied to anything one wishes to denigrate.
> 
> Of course there are people who misuse regexes. But I am quite sure,
> especially in the Python community, there are just as many who fail to
> use them when they are appropriate which is just as bad.

Judging by a few posts on the list lately, I'd say it is highly relevant
to Python itself.  Too many people have only a vague notion of a problem
they'd like to solve and although they don't really understand the
problem, they've heard Python is a good language to learn, so they ask
how they can solve that problem with Python.

Now, this certainly can work for a person who's already experienced in
several languages and who already understands the problem.  For others,
it's very much now two intractable problems.



From torriem at gmail.com  Mon Nov  2 23:38:04 2015
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 02 Nov 2015 21:38:04 -0700
Subject: Regular expressions
In-Reply-To: <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
Message-ID: <56383A2C.1020202@gmail.com>

On 11/02/2015 09:23 PM, rurpy--- via Python-list wrote:
>> My completely unsolicited advice is that regular expressions shouldn't be
>> very high on the list of things to learn.  They are very useful, and very
>> tricky and prone many problems that can and should be learned to be
>> resolved with much simpler methods.  If you really want to learn regular
>> expressions, that's great but the problem you posed is not one for which
>> they are the best solution.  Remember simpler is better than complex.
> 
> Regular expressions should be learned by every programmer or by anyone
> who wants to use computers as a tool.  They are a fundamental part of
> computer science and are used in all sorts of matching and searching 
> from compilers down to your work-a-day text editor.
> 
> Not knowing how to use them is like an auto mechanic not knowing how to 
> use a socket wrench.

Not quite.  Core language concepts like ifs, loops, functions,
variables, slicing, etc are the socket wrenches of the programmer's
toolbox.  Regexs are like an electric impact socket wrench.  You can do
the same work without it, but in many cases it's slower. But you have to
learn the other hand tools first in order to really use the electric
driver properly (understanding torques, direction of threads, etc), lest
you wonder why you're breaking off so many bolts with the torque of the
impact drive.




From torriem at gmail.com  Mon Nov  2 23:46:17 2015
From: torriem at gmail.com (Michael Torrie)
Date: Mon, 02 Nov 2015 21:46:17 -0700
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A742DCC@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A742DCC@DCBL123VX.root.sutterhealth.org>
Message-ID: <56383C19.8080607@gmail.com>

On 11/02/2015 08:52 AM, Robinson, Wendy wrote:
> [cid:image001.png at 01D11543.5ED11D50]

Just FYI this mailing list group is tied with with a system called
USENET which is plain text only, so most of us can't see your
attachment.  This may help you copy the text to your messages in plain
text form:

http://www.howtogeek.com/howto/windows-vista/copy-to-the-clipboard-from-the-windows-command-prompt/

Did you read what Peter Otten said in reply to your original message and
did that not work?

Sometimes on Windows you can double-click a python file and it will run.
However many python programs don't display graphical elements so you'll
just see a black console window flash and disappear.  That's why it's
probably important while learning Python to become comfortable with the
command prompt.

Alternatively use the IDLE program that comes with Python to edit and
run your programs in a graphical environment.  I think if you are on
Windows and are unfamiliar with the command prompt I would recommend
this course of action.  Should be in the Start menu.



From steve at pearwood.info  Tue Nov  3 01:47:33 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 03 Nov 2015 17:47:33 +1100
Subject: Modern recommended exception handling practices?
References: <52739457-5f7a-48ea-8835-9fc8934174f9@googlegroups.com>
Message-ID: <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>

Hi Vasudev, and welcome.

Sorry for the delay in replying to your questions. My answers inline, below.


On Fri, 30 Oct 2015 04:43 am, vasudevram wrote:

> Are there any modern (i.e. for current versions of Python 2 and 3)
> recommended exception handling practices?

When you say "modern", it sounds like you want to contrast them with "old
fashioned and obsolete" exception-handling practices. I don't know if there
are any obsolete exception-handling practices in Python.

I would follow these rules, as best I am able to:


(1) Remember that, in general, exception catching is very course-grained.
You can catch a particular kind of exception, but you don't know which
specific line of code or expression caused it, the reason why, or where in
the `try` block it was raised. The entire `try` clause is as fine-grained
as you get.

One consequence is that it is easy to write exceptional handling code which
is wrong and buggy:

http://blogs.msdn.com/b/oldnewthing/archive/2004/04/22/118161.aspx

http://blogs.msdn.com/b/oldnewthing/archive/2005/01/14/352949.aspx


To avoid this, the `try` block should cover the least amount of code
possible. For example, suppose you have this:

    try:
        result = calculate(mylist.index(x), func(key))
    except ValueError:
        # thrown by mylist.index if x is not found
        result = "x not found"


That code is probably unsafe, because you can't be sure that either
func(key) or calculate(...) itself might not throw a ValueError. Unless you
can guarantee that there are no circumstances where that might happen, or
if it doesn't matter which of the three expressions throws the ValueError,
you are better off writing this:

    try:
        idx = mylist.index(x)
    except ValueError:
        result = "x not found"
    else:
        result = calculate(idx, func(key))


(2) Catch only the exceptions that you expect and can genuinely recover
from. Don't use `try...except` as a way to cover up and hide the fact that
an error occurred.

One of my favourite quotes about programming is this one:

   "I find it amusing when novice programmers believe their main
    job is preventing programs from crashing. ... More experienced
    programmers realize that correct code is great, code that
    crashes could use improvement, but incorrect code that doesn?t
    crash is a horrible nightmare."
    -- Chris Smith

In context of Python, "crash" means "raise an exception". Exceptions are
your best friend: they show you were your bugs are. How can you fix bugs if
you don't know where they are?

You should only catch the exceptions that you expect to occur, and can
recover from. Everything else should be allowed to raise an exception, so
you can *see* that something is broken. Now you know that something in your
code has a bug, and needs to be fixed.

Consequently, you should never (well, *almost* never) be tempted to write a
bare `except` clause, or even `except Exception`. They are almost always
too broad, and catch too much.

Bare `except` clauses are very possibly *literally the worst* thing that you
can write in Python:

https://realpython.com/blog/python/the-most-diabolical-python-antipattern/


(3) One exception to rule (2) is that sometimes it is useful to surround
your entire main program with a `try...except`, for the purposes of logging
errors and presenting a nice clean error message to your users:

    try:
        main()
    except Exception as err:
        # Catch any and all unexpected exceptions.
        log(err)
        alert("A serious problem has occurred and MyApplication must quit. " 
              "Please contact the help desk on 999-999-999.")
        sys.exit(1)


(4) Remember that Python matches exceptions from top down, so more specific
exceptions (subclasses of a less specific exception) need to come first. So
if we write this:

    try:
        ...
    except Exception:
        print("something unexpected occurred")
    except TypeError:
        print("this is expected")


the TypeError will be caught by the first except clause, and treated as
something unexpected. Swap the order of the except clauses, and you will be
fine:

    try:
        ...
    except TypeError:
        print("this is expected")
    except Exception:
        print("something unexpected occurred")


(5) Remember that often you can avoid exceptions instead of catching
them. "Look Before You Leap" (LBYL) may be a perfectly good alternative:

    if item in mylist:
        idx = mylist.index(item)
        process(idx)
    else:
        result = "not found"


but be sensitive to the amount of work done. The above code searches the
list twice instead of just once.


(6) In general, you can consider setting up a "try" block to be practically
free in Python (which is the opposite to Java, where exception handling is
always expensive). If no exception occurs, there is virtually no difference
in speed between:

    func(x)

and

    try:
        func(x)
    except:
        pass


but if an exception does occur, actually catching it is quite costly. This
idiom is usually called "Easier to Ask for Forgiveness than Permission"
(EAFP).


(7) So which is faster, LBYL or catching the exception? That is extremely
sensitive to not just the specific operations being performed, but how
often the exceptional cases occur. In general, you must measure your code
to know.

But as a very rough rule of thumb, consider looking up a key in a dict:

    if key in mydict:
        result = mydict[key]

versus

    try:
        result = mydict[key]
    except KeyError:
        pass


In my experience, catching the KeyError is about ten times more costly than
testing for the key's presence. So if your keys are missing more than one
time in ten, it's probably better to use LBYL.


(8) Remember that this is called *exception handling*, not "error handling".
In Python, exceptions are not just for errors.

For example, Python extensively uses StopIteration for flow-control. When an
iterator runs out of items, it raises an exception, which the Python
interpreter catches to recognise the end of the iterator. You can do the
same in your own code, invent your own protocols that use exceptions to
signal exceptional cases.

Some very highly respected people like Joel Spolsky and Raymond Chen dislike
exceptions as flow-control, calling them just a thinly disguised GOTO:

http://www.joelonsoftware.com/items/2003/10/13.html

http://blogs.msdn.com/b/oldnewthing/archive/2005/01/06/347666.aspx

and while it is true that exceptions are a kind of GOTO, that doesn't mean
much. For-loops, and if-elif-else are a kind of GOTO too, and we don't
worry about them. (For example, you can't use an exception to jump *into* a
function, only out of one.)


See also:

http://c2.com/cgi/wiki?AvoidExceptionsWheneverPossible

http://c2.com/cgi/wiki?ExceptionsAreOurFriends




[...]
> I realize that there may not be any recommended standard practices for
> this, or they may be more than one set, because of differences of opinion.
> For example, several years back, there was a somewhat controversial thread
> about, IIRC, checked vs. unchecked Java exceptions, maybe triggered by
> some post on Elliot Rusty Harold's site (he used to write a lot about
> Java, both blog posts and books).

Java is, as far as I know, the only language with checked exceptions.
Certainly Python doesn't have them. I know that checked exceptions are very
controversial in the Java community, but I understand that Java's creator
James Gosling eventually came out to say that they were a mistake.

In Python's case, you should document what exceptions you expect your
functions to raise, but you must not assume that such documentation is ever
complete. For example, consider the operator "+". We know that + will raise
a TypeError:

py> 2 + "2"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'

but if one of the operands is a custom type, it could raise *anything*:


py> class X:
...     def __add__(self, other):
...             raise OSError
...
py> X() + 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in __add__
OSError

Does this mean you should *catch* everything? No. See Rule (2) above. Unless
you are expecting an X instance in your code, the presence of one is
probably a bug. The *unexpected* OSError will be the exception that reveals
this bug, and allows you to fix it.




-- 
Steven



From nobody at nowhere.invalid  Tue Nov  3 02:10:58 2015
From: nobody at nowhere.invalid (Nobody)
Date: Tue, 03 Nov 2015 07:10:58 +0000
Subject: Unbuffered stderr in Python 3
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <pan.2015.11.03.07.10.58.482000@nowhere.invalid>

On Mon, 02 Nov 2015 18:52:55 +1100, Steven D'Aprano wrote:

> In Python 2, stderr is unbuffered.
> 
> In most other environments (the shell, C...) stderr is unbuffered.
> 
> It is usually considered a bad, bad thing for stderr to be buffered. What
> happens if your application is killed before the buffer fills up? The
> errors in the buffer will be lost.
> 
> So how come Python 3 has line buffered stderr? And more importantly, how
> can I turn buffering off?

It's probably related to the fact that std{in,out,err} are Unicode
streams. 

	> type(sys.stderr)
	<class '_io.TextIOWrapper'>
	> type(sys.stderr.buffer)
	<class '_io.BufferedWriter'>
	> type(sys.stderr.buffer.raw)
	<class '_io.FileIO'>

It appears that you can turn it off with:

	sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
or:
	sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach())

This results in a sys.stderr which appears to work and whose
.line_buffering property is False.



From steve at pearwood.info  Tue Nov  3 02:15:06 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 03 Nov 2015 18:15:06 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
Message-ID: <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>

On Tue, 3 Nov 2015 03:23 pm, rurpy at yahoo.com wrote:

> Regular expressions should be learned by every programmer or by anyone
> who wants to use computers as a tool. ?They are a fundamental part of
> computer science and are used in all sorts of matching and searching
> from compilers down to your work-a-day text editor.

You are absolutely right.

If only regular expressions weren't such an overly-terse, cryptic
mini-language, with all but no debugging capabilities, they would be great.

If only there wasn't an extensive culture of regular expression abuse within
programming communities, they would be fine.

All technologies are open to abuse. But we don't say:

  Some people, when confronted with a problem, think "I know, I'll use
  arithmetic." Now they have two problems.

because abuse of arithmetic is rare. It's hard to misuse it, and while
arithmetic can be complicated, it's rare for programmers to abuse it. But
the same cannot be said for regexes -- they are regularly misused, abused,
and down-right hard to use right even when you have a good reason for using
them:

http://www.thedailywtf.com/articles/Irregular_Expression

http://blog.codinghorror.com/regex-use-vs-regex-abuse/

http://psung.blogspot.com.au/2008/01/wonderful-abuse-of-regular-expressions.html


If there is one person who has done more to create a regex culture, it is
Larry Wall, inventor of Perl. Even Larry Wall says that regexes are
overused and their syntax is harmful, and he has recreated them for Perl 6:

http://www.perl.com/pub/2002/06/04/apo5.html

Oh, and the icing on the cake, regexes can be a security vulnerability too:

https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS



-- 
Steven



From steve at pearwood.info  Tue Nov  3 02:15:06 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 03 Nov 2015 18:15:06 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
Message-ID: <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>

On Tue, 3 Nov 2015 03:23 pm, rurpy at yahoo.com wrote:

> Regular expressions should be learned by every programmer or by anyone
> who wants to use computers as a tool. ?They are a fundamental part of
> computer science and are used in all sorts of matching and searching
> from compilers down to your work-a-day text editor.

You are absolutely right.

If only regular expressions weren't such an overly-terse, cryptic
mini-language, with all but no debugging capabilities, they would be great.

If only there wasn't an extensive culture of regular expression abuse within
programming communities, they would be fine.

All technologies are open to abuse. But we don't say:

  Some people, when confronted with a problem, think "I know, I'll use
  arithmetic." Now they have two problems.

because abuse of arithmetic is rare. It's hard to misuse it, and while
arithmetic can be complicated, it's rare for programmers to abuse it. But
the same cannot be said for regexes -- they are regularly misused, abused,
and down-right hard to use right even when you have a good reason for using
them:

http://www.thedailywtf.com/articles/Irregular_Expression

http://blog.codinghorror.com/regex-use-vs-regex-abuse/

http://psung.blogspot.com.au/2008/01/wonderful-abuse-of-regular-expressions.html


If there is one person who has done more to create a regex culture, it is
Larry Wall, inventor of Perl. Even Larry Wall says that regexes are
overused and their syntax is harmful, and he has recreated them for Perl 6:

http://www.perl.com/pub/2002/06/04/apo5.html

Oh, and the icing on the cake, regexes can be a security vulnerability too:

https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS



-- 
Steven



From rosuav at gmail.com  Tue Nov  3 02:16:18 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 3 Nov 2015 18:16:18 +1100
Subject: Modern recommended exception handling practices?
In-Reply-To: <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>
References: <52739457-5f7a-48ea-8835-9fc8934174f9@googlegroups.com>
 <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqVj8jbQzpQTcyfKbLbpvm-2qo9xUoGEAst0_Bf2ReCWA@mail.gmail.com>

On Tue, Nov 3, 2015 at 5:47 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Fri, 30 Oct 2015 04:43 am, vasudevram wrote:
>
>> Are there any modern (i.e. for current versions of Python 2 and 3)
>> recommended exception handling practices?
>
> When you say "modern", it sounds like you want to contrast them with "old
> fashioned and obsolete" exception-handling practices. I don't know if there
> are any obsolete exception-handling practices in Python.

Aside from string exceptions and the "except Type, e:" syntax, I would
agree with you. Actually, I can't think of any "obsolete
exception-handling practices" in any language. Exception handling is
pretty straight-forward: you raise an exception in one place, and you
catch it in another.

> Bare `except` clauses are very possibly *literally the worst* thing that you
> can write in Python:
>
> https://realpython.com/blog/python/the-most-diabolical-python-antipattern/

I would actually like to disallow the bare except, in the same way
that I would disallow the Py2 input() function. In the rare cases
where you really do want to catch *every* exception (eg at a boundary
between a web server and a request handler, where you would log the
exception and return a 500), it should be spelled "except
BaseException [as e]:", same as you should use "eval(raw_input())" in
those extremely rare cases where you actually want to take keyboard
input and evaluate it.

But more generally, the over-broad exception handler is a nasty anti-pattern.

> (5) Remember that often you can avoid exceptions instead of catching
> them. "Look Before You Leap" (LBYL) may be a perfectly good alternative:
>
>     if item in mylist:
>         idx = mylist.index(item)
>         process(idx)
>     else:
>         result = "not found"
>
>
> but be sensitive to the amount of work done. The above code searches the
> list twice instead of just once.

Not to mention having race condition possibilities. There are a few
places where this is useful, though:

start_time = time()
work_done = do_some_work()
time_spent = time()-start_time or 1
print(f"Did {work_done} jobs in {time_spent} secs: {work_done/time_spent} j/s")

The "or 1" is a quick check that means we don't divide by zero. The
performance figure becomes meaningless, but if this is a rare case,
that's probably fine.

> (7) So which is faster, LBYL or catching the exception? That is extremely
> sensitive to not just the specific operations being performed, but how
> often the exceptional cases occur. In general, you must measure your code
> to know.
>
> But as a very rough rule of thumb, consider looking up a key in a dict:
>
>     if key in mydict:
>         result = mydict[key]
>
> versus
>
>     try:
>         result = mydict[key]
>     except KeyError:
>         pass
>
>
> In my experience, catching the KeyError is about ten times more costly than
> testing for the key's presence. So if your keys are missing more than one
> time in ten, it's probably better to use LBYL.

This is actually a tribute to dict performance for key lookup (since
that's one of the important operations in a hashtable). It's NOT the
case for a list.


Exceptions are the "other way" to return something. In a function that
always returns a string, returning None is distinguishable (in the
same way that a C function can return a NULL pointer); in a function
that returns absolutely any object, the only way to signal "no object
to return" is to raise an exception. That's why StopIteration exists,
for instance. Exceptions are a normal part of program flow - they
signal an "exceptional condition" in some small area, but it's normal
to cope with exceptional conditions.

ChrisA


From steve at pearwood.info  Tue Nov  3 02:22:30 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 03 Nov 2015 18:22:30 +1100
Subject: Modern recommended exception handling practices?
References: <52739457-5f7a-48ea-8835-9fc8934174f9@googlegroups.com>
 <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7.1446534982.8789.python-list@python.org>
Message-ID: <563860b9$0$1589$c3e8da3$5496439d@news.astraweb.com>

On Tue, 3 Nov 2015 06:16 pm, Chris Angelico wrote:

> Not to mention having race condition possibilities.

Arrggghhh! I knew there was something else I wanted to say.

You're right. Sometimes you *have* to use exception handling code. Take this
for example:


if os.path.exists(pathname):
    f = open(pathname)

That might be good enough for a quick and dirty script, but it's wrong,
because there's a race condition between the time you check whether the
file exists and the time you actually try to open it. (There are other
problems too: just because the file exists doesn't mean you have read
permission to it.) A lot can happen in the few microseconds between
checking for the existence of the file and actually opening it -- the file
could be renamed or deleted.

https://en.wikipedia.org/wiki/Time_of_check_to_time_of_use


-- 
Steven



From rosuav at gmail.com  Tue Nov  3 02:52:27 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 3 Nov 2015 18:52:27 +1100
Subject: Modern recommended exception handling practices?
In-Reply-To: <563860b9$0$1589$c3e8da3$5496439d@news.astraweb.com>
References: <52739457-5f7a-48ea-8835-9fc8934174f9@googlegroups.com>
 <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7.1446534982.8789.python-list@python.org>
 <563860b9$0$1589$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqHCq9HFgLNcWnW8BvLk1yQQf=0M-yWre9MRQKhu-1CHg@mail.gmail.com>

On Tue, Nov 3, 2015 at 6:22 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> A lot can happen in the few microseconds between
> checking for the existence of the file and actually opening it -- the file
> could be renamed or deleted.

And a lot of microseconds can happen between two opcodes, too. Even
inside a Python script, it's possible for threads or other arbitrary
code execution to get in your way:

if "foo" in counters:
    # context switch here!
    process(counters["foo"])

Garbage collection can happen at any time. Here's an (admittedly
arbitrary) example of how the above could be broken:

>>> class X:
...     def __init__(self, name, dict):
...         self.dict = dict; self.name = name
...         self.dict[self.name] = 0
...     def frob(self):
...         self.dict[self.name] += 1
...     def __del__(self):
...         del self.dict[self.name]
...
>>> counters = {}
>>> x = X("foo", counters)
>>> x.refcycle = x
>>> counters
{'foo': 0}
>>> del x
>>> counters
{'foo': 0}
>>> gc.collect()
10
>>> counters
{}

If the cycle-detecting garbage collector happens to be called
immediately after the 'if', you'll get an exception.

So I suppose what you might do is this:

try:
    # Optimization: Since a lot of these names won't be
    # in the dict, we check first rather than relying on the
    # exception. Since counters get removed in the __del__
    # method, we can't depend 100% on the 'in' check,
    # but an unnecessary try block is cheap.
    if "foo" in counters:
        process(counters["foo"])
except KeyError:
    pass

But any time you need a block comment to justify your code, you'd
better be REALLY sure the performance benefit is worth the complexity.

For reliability, expect exceptions.

ChrisA


From nick.a.sarbicki at gmail.com  Tue Nov  3 03:43:10 2015
From: nick.a.sarbicki at gmail.com (Nick Sarbicki)
Date: Tue, 3 Nov 2015 08:43:10 +0000
Subject: Regular expressions
In-Reply-To: <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAGuvt93-ktpSzbrEPRfni1hbu5oKaQXKgC_wGknGry8CCSqzAw@mail.gmail.com>

On Tue, Nov 3, 2015 at 7:15 AM, Steven D'Aprano <steve at pearwood.info> wrote:

> On Tue, 3 Nov 2015 03:23 pm, rurpy at yahoo.com wrote:
>
> > Regular expressions should be learned by every programmer or by anyone
> > who wants to use computers as a tool.  They are a fundamental part of
> > computer science and are used in all sorts of matching and searching
> > from compilers down to your work-a-day text editor.
>
> You are absolutely right.
>
> If only regular expressions weren't such an overly-terse, cryptic
> mini-language, with all but no debugging capabilities, they would be great.
>
> If only there wasn't an extensive culture of regular expression abuse
> within
> programming communities, they would be fine.
>
> All technologies are open to abuse. But we don't say:
>
>   Some people, when confronted with a problem, think "I know, I'll use
>   arithmetic." Now they have two problems.
>
> because abuse of arithmetic is rare. It's hard to misuse it, and while
> arithmetic can be complicated, it's rare for programmers to abuse it. But
> the same cannot be said for regexes -- they are regularly misused, abused,
> and down-right hard to use right even when you have a good reason for using
> them:
>
> http://www.thedailywtf.com/articles/Irregular_Expression
>
> http://blog.codinghorror.com/regex-use-vs-regex-abuse/
>
>
> http://psung.blogspot.com.au/2008/01/wonderful-abuse-of-regular-expressions.html
>
>
> If there is one person who has done more to create a regex culture, it is
> Larry Wall, inventor of Perl. Even Larry Wall says that regexes are
> overused and their syntax is harmful, and he has recreated them for Perl 6:
>
> http://www.perl.com/pub/2002/06/04/apo5.html
>
> Oh, and the icing on the cake, regexes can be a security vulnerability too:
>
>
> https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS
>
>
>
> --
> Steven
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>


+1

I agree that regex is an entirely necessary part of a programmers toolkit,
but dear god some people need to be taught restraint. The majority of
people I talk about regex to have no idea when and where it shouldn't be
used.

As an example part of my job is bringing our legacy Python code into the
modern day, and one of the largest roadblocks is the amount of regex used.

Some is necessary.

Some can be replaced by an `if word in str` or something similarly basic.

Some spans hundreds of lines and causes acute alopecia.

Just yesterday I found a colleague trying to parse HTML with regex.

So yes, teach regex, but teach it after the basics, and please emphasise
when it is appropriate to use it.

Yes I am bitter.

- Nick.


From alister.nospam.ware at ntlworld.com  Tue Nov  3 03:50:34 2015
From: alister.nospam.ware at ntlworld.com (alister)
Date: Tue, 3 Nov 2015 08:50:34 +0000 (UTC)
Subject: Detection of a specific sound
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <mailman.1.1446522557.8789.python-list@python.org>
Message-ID: <n19sgq$ppu$1@speranza.aioe.org>

On Mon, 02 Nov 2015 20:49:03 -0700, Michael Torrie wrote:

> On 10/25/2015 06:17 PM, Montana Burr wrote:
>> I'm looking for a library that will allow Python to listen for the
>> shriek of a smoke alarm. Once it detects this shriek, it is to notify
>> someone. Ideally, specificity can be adjusted for the user's
>> environment. For example, I expect to need moderate specificity as I
>> live in a quiet neighborhood, but an apartment dweller might need more.
>> 
>> I'm thinking of recording a smoke alarm and having the program try to
>> find the recorded sound in the stream from the microphone.
>> 
>> Any help is greatly appreciated!
> 
> At this point, from what you say, your problem is not a python one. It's
> a more general problem that you have to tackle.  In other words how are
> you going to identify this one sound amongst background noise?  Once you
> know that, then you can apply Python to the problem.
> 
> I suggest you spend some time exploring how you would actually go about
> recognizing a particular sound algorithmically.  Relevant tops of
> research include: digital signal processing and fourier analysis.
> 
> A quick google search reveals some info that may point you in the right
> direction:
> 
> https://blog.adafruit.com/2015/01/12/think-dsp-introduction-to-signal-
processing-using-python/
> http://samcarcagno.altervista.org/blog/basic-sound-processing-python/
> 
> I know very little about the subject, but if it were me, my naive
> approach would be to do fourier analysis on the sound you are trying to
> identify to pick out the sound's fingerprint (certain component
> waveforms that stand out), and then do the same analysis on your audio
> stream, looking for this footprint.

Personally I would forget trying to analyse sound & see if there is any 
way to get an input signal direct from the alarm (even if that is as 
crude as taking a tap from the siren feed wires) 

This application sounds far to critical for anything else.



-- 
 ______________________________________
/ "Can't you just gesture hypnotically \
| and make him disappear?"             |
|                                      |
| "It does not work that way. RUN!" -- |
| Hadji on metaphyics and Mandrake in  |
\ "Johnny Quest"                       /
 --------------------------------------
   \
    \
        .--.
       |o_o |
       |:_/ |
      //   \ \
     (|     | )
    /'\_   _/`\
    \___)=(___/



From alister.nospam.ware at ntlworld.com  Tue Nov  3 04:04:20 2015
From: alister.nospam.ware at ntlworld.com (alister)
Date: Tue, 3 Nov 2015 09:04:20 +0000 (UTC)
Subject: installer user interface glitch ?
References: <20151101081401312.7CB171092D5B3FA6@griff-18f062b3e>
 <mailman.11.1446372398.4463.python-list@python.org>
 <5cf3c8b2-4095-4e73-98bf-dcc8d776005d@googlegroups.com>
 <mailman.27.1446393155.4463.python-list@python.org>
 <1e5939df-d2c3-4e08-ab26-36c81b0218c5@googlegroups.com>
Message-ID: <n19tak$rau$1@speranza.aioe.org>

On Sun, 01 Nov 2015 08:24:22 -0800, rurpy wrote:

> On Sunday, November 1, 2015 at 8:52:55 AM UTC-7, Chris Angelico wrote:
>> On Mon, Nov 2, 2015 at 2:43 AM, rurpy--- via Python-list
>> <python-list at python.org> wrote:
>> > Why, oh why, do the python.org front page and other pages that offer
>> > a Windows download not say a word about it not running on Windows XP?
>> >
>> > Even if one is anal enough to go to the page about the 3.5 release.
>> >   https://www.python.org/downloads/release/python-350/
>> > a page with a lot of Windows-specific info, there is not a word about
>> > XP.
>> 
>> A partial answer to that is in PEP 11:
>> 
>> https://www.python.org/dev/peps/pep-0011/#microsoft-windows
>> 
>> Windows XP isn't special here. There's no mention of Python 2.7 not
>> working on Windows 95, because it's simply an unsupported operating
>> system. The only reason that people keep coming asking about XP and not
>> (say) Win2K is that there are a lot more XP boxes out there. Do the
>> other download pages need to stipulate which versions of which OSes
>> they support, or should that be left up to the installer?
> 
> I dont recall seeing anyone posting asking why they could not get Python
> to install on Windows 95 recently.  I only read this group
> intermittently but I have seen *many* posts asking why they couldnt
> install on XP.
> 
> You acknowledge yourself: "there are a lot more XP boxes out there."
> 
>> There *is* a plan to have the installer give a better error message for
>> this situation.
> 
> A better message from the installer is necessary but not sufficient.
> Don't make people go through the effort to download the whole thing, do
> their planning and preparations for using or upgrading Python only to
> discover at the last moment it wont work.
> 
> That is really shitty customer relations.
> 
> The reality is that people trying install Python-3.5 on XP *is* a
> problem.  Telling them they should have read some obscure release notes
> is not a solution.
> 
>> But I don't think the web site necessarily has to have noise about old
>> versions of OSes. Where would you draw the line?
> 
> I think my responses above answer that.

I would have to agree, at least in general

1) The web page should always list the Versions of Windows that ARE 
supported.

2) As support for Win XP has only just ceased it should be specifically 
mentioned for V3.5, I would see no need to continue with this for V3.6 +
Likewise Win95 2000 etc. should have been mentioned at the release when 
support was dropped & no further

As adding a "Not supported on Win XP or Win 7 Minimum" notice is such a 
minimal "Bug Fix" I don't see the issue. 



-- 
 _____________________
< U.S. Postal Service >
 ---------------------
   \
    \
        .--.
       |o_o |
       |:_/ |
      //   \ \
     (|     | )
    /'\_   _/`\
    \___)=(___/



From __peter__ at web.de  Tue Nov  3 04:25:26 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 03 Nov 2015 10:25:26 +0100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
Message-ID: <n19ui8$df7$1@ger.gmane.org>

Michael Torrie wrote:

> On 11/02/2015 07:42 PM, Tim Chase wrote:
>> On 2015-11-02 20:09, Seymore4Head wrote:
>>> How do I make a regular expression that returns true if the end of
>>> the line is an asterisk
>> 
>> Why use a regular expression?
>> 
>>   if line[-1] == '*':
>>     yep(line)
>>   else:
>>     nope(line)
> 
> Indeed, sometimes Jamie Zawinski's is often quite appropriate:
> 
>     Some people, when confronted with a problem, think "I know, I'll use
> regular expressions." Now they have two problems.

Incidentally the code example has two "problems", too.

- What about the empty string?
- What about lines with a trailing "\n", i. e. as they are usually delivered
  when iterating over a file?

Below is a comparison of some of your options. The "one obvious way" 
line.rstrip("\n").endswith("*") is not included ;)

$ cat starry_table.py 
import re


def show_table(data, header):
    rows = [header]
    rows.extend([str(c) for c in row] for row in data)
    widths = [max(len(row[i]) for row in rows) for i in range(len(header))]
    template = "  ".join("{:%d}" % w for w in widths)
    for row in rows:
        print(template.format(*row))


def compare(sample_lines):
    for line in sample_lines:
        got_re = bool(re.compile("\*$").search(line))
        got_re_M = bool(re.compile("\*$", re.M).search(line))
        got_endswith = line.endswith("*")
        got_endswith2 = line.endswith(("*", "*\n"))
        got_substring = line[-1:] == "*"
        try:
            got_char = line[-1] == "*"
        except IndexError:
            got_char = "#exception"
        results = (
            got_re, got_re_M,
            got_endswith, got_endswith2,
            got_substring, got_char)
        yield (
            ["", "X"][len(set(results)) > 1],
            repr(line)) + results


SAMPLE = ["", "\n", "foo\n", "*\n", "*", "foo*", "foo*\n", "foo*\nbar"]
HEADER = [
    "", "line", "regex", "re.M",
    "endswith", 'endswith(("*", "*\\n"))',
    "substring", "char"]

if __name__ == "__main__":
    show_table(compare(SAMPLE), HEADER)


$ python3 starry_table.py 
   line         regex  re.M   endswith  endswith(("*", "*\n"))  substring  char      
X  ''           False  False  False     False                   False      #exception
   '\n'         False  False  False     False                   False      False     
   'foo\n'      False  False  False     False                   False      False     
X  '*\n'        True   True   False     True                    False      False     
   '*'          True   True   True      True                    True       True      
   'foo*'       True   True   True      True                    True       True      
X  'foo*\n'     True   True   False     True                    False      False     
X  'foo*\nbar'  False  True   False     False                   False      False     




From motoom at xs4all.nl  Tue Nov  3 04:39:46 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Tue, 3 Nov 2015 10:39:46 +0100
Subject: Puzzled
In-Reply-To: <56383C19.8080607@gmail.com>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A742DCC@DCBL123VX.root.sutterhealth.org>
 <56383C19.8080607@gmail.com>
Message-ID: <2E07C1E1-82C0-4919-BF9E-C9BF2EB0B3D4@xs4all.nl>


> On 03 Nov 2015, at 05:46, Michael Torrie <torriem at gmail.com> wrote:
> Sometimes on Windows you can double-click a python file and it will run.

The first thing I do on Windows after installing Python: edit the registry
so that the 'open' key is changed to 'run', and 'edit with IDLE' becomes 'open'.

I like to see my scripts in IDLE before I run them ;-)

Greetings,



From nicholas.cole at gmail.com  Tue Nov  3 05:32:33 2015
From: nicholas.cole at gmail.com (Nicholas Cole)
Date: Tue, 3 Nov 2015 10:32:33 +0000
Subject: venv issues
Message-ID: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>

I'm using python3.5 (installed from binaries) on the latest OS X.

I have a curious issue with virtual environments on this machine (but
not on my other machine).


$ python3.5 -m venv testenv
$ source testenv/bin/activate
(testenv)$ python -m pip
/private/tmp/testenv/bin/python: No module named pip
$

Logging in as a different user and creating a venv works perfectly, so
it's clearly a config issue somewhere, but I've tried removing
~/.bashrc and ~/.bash_profile and that doesn't help.

The sys.path for that venv is: ['',
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python35.zip',
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5',
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/plat-darwin',
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/lib-dynload',
'/private/tmp/testenv/lib/python3.5/site-packages']

I'm sure I'm overlooking something obvious, but can anyone suggest what?

Nicholas


From python.list at tim.thechases.com  Tue Nov  3 06:50:18 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 3 Nov 2015 05:50:18 -0600
Subject: Regular expressions
In-Reply-To: <n19ui8$df7$1@ger.gmane.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
Message-ID: <20151103055018.535e3e42@bigbox.christie.dr>

On 2015-11-03 10:25, Peter Otten wrote:
> >>> How do I make a regular expression that returns true if the end
> >>> of the line is an asterisk
> >> 
> >> Why use a regular expression?
> >> 
> >>   if line[-1] == '*':
> >>     yep(line)
> >>   else:
> >>     nope(line)
> 
> Incidentally the code example has two "problems", too.
> 
> - What about the empty string?

Good catch: .endswith() works better.

> - What about lines with a trailing "\n", i. e. as they are usually
> delivered when iterating over a file?

Then your string *doesn't* end with a "*", but rather with a
newline. ;-)

Though according to the OP's specs, the following function would work
too:

  def ends_in_asterisk(s):
    return True

It *does* return True if the line ends in an asterisk (no requirement
to make the function return False under any other conditions).

-tkc







From python.list at tim.thechases.com  Tue Nov  3 06:53:39 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 3 Nov 2015 05:53:39 -0600
Subject: Regular expressions
In-Reply-To: <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
Message-ID: <20151103055339.247c5230@bigbox.christie.dr>

On 2015-11-02 22:17, Seymore4Head wrote:
> On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
> <python.list at tim.thechases.com> wrote:
> 
> >On 2015-11-02 20:09, Seymore4Head wrote:
> >> How do I make a regular expression that returns true if the end
> >> of the line is an asterisk
> >
> >Why use a regular expression?
> >
> Because that is the part of Python I am trying to learn at the
> moment. Thanks

Ah, well that's an entirely different problem-space, so then you
would want to use MRAB's answer

  r = re.compile(r"\*$")

-tkc





From arsh840 at gmail.com  Tue Nov  3 06:54:30 2015
From: arsh840 at gmail.com (Arshpreet Singh)
Date: Tue, 3 Nov 2015 03:54:30 -0800 (PST)
Subject: Python PNG Viewer(Browser Based)
Message-ID: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>

Hello Everyone,

I am looking for Browser-based PNG file viewer written in
Python.(Flask framework preferably)

Following project(Flask-Based) provides many things(File manager as
well as file viewer)  but it does not support PNG files.

https://github.com/vmi356/filemanager

Any idea if I have to write my own browser based PNG viewer from
scratch(Using PIL or other required library)

On the other side if I have to write only Desktop-based only two lines
are enough to do many things:

Like,

from PIL import Image
f = Image.open("file.png").show()


But I am not getting right sense that how to make possible using Python+Flask.

Hope I am able to tell my problem?


From wolfgang.maier at biologie.uni-freiburg.de  Tue Nov  3 07:27:14 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Tue, 3 Nov 2015 13:27:14 +0100
Subject: venv issues
In-Reply-To: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
References: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
Message-ID: <n1a971$isd$1@ger.gmane.org>

On 03.11.2015 11:32, Nicholas Cole wrote:
> I'm using python3.5 (installed from binaries) on the latest OS X.
>
> I have a curious issue with virtual environments on this machine (but
> not on my other machine).
>
>
> $ python3.5 -m venv testenv
> $ source testenv/bin/activate
> (testenv)$ python -m pip
> /private/tmp/testenv/bin/python: No module named pip
> $
>
> Logging in as a different user and creating a venv works perfectly, so
> it's clearly a config issue somewhere, but I've tried removing
> ~/.bashrc and ~/.bash_profile and that doesn't help.
>
> The sys.path for that venv is: ['',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python35.zip',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/plat-darwin',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/lib-dynload',
> '/private/tmp/testenv/lib/python3.5/site-packages']
>

Is there something special about your /private/tmp folder? In other 
words, do things work if you create a venv in a different place.
If you go to /private/tmp/testenv/lib/python3.5/site-packages is there a 
pip folder and what are its permission settings?



From denismfmcmahon at gmail.com  Tue Nov  3 07:38:12 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Tue, 3 Nov 2015 12:38:12 -0000 (UTC)
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
Message-ID: <n1a9rk$s40$1@dont-email.me>

On Mon, 02 Nov 2015 22:17:49 -0500, Seymore4Head wrote:

> On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
> <python.list at tim.thechases.com> wrote:
> 
>>On 2015-11-02 20:09, Seymore4Head wrote:

>>> How do I make a regular expression that returns true if the end of the
>>> line is an asterisk

>>Why use a regular expression?

> Because that is the part of Python I am trying to learn at the moment.

The most important thing to learn about regular expressions is when to 
use them and when not to use them.

Returning true if the last character in a string is an asterisk is almost 
certainly a brilliant example of when not to use a regular expression. 
Here are some timings I tested:

#!/usr/bin/python

import re

import timeit

patt = re.compile("\*$")

start_time = timeit.default_timer()
for i in range(1000000):
    x = re.match("\*$", "test 1")
elapsed = timeit.default_timer() - start_time
print "re, false", elapsed

start_time = timeit.default_timer()
for i in range(1000000):
    x = re.match("\*$", "test *")
elapsed = timeit.default_timer() - start_time
print "re, true", elapsed

start_time = timeit.default_timer()
for i in range(1000000):
    x = patt.match("test 1")
elapsed = timeit.default_timer() - start_time
print "compiled re, false", elapsed

start_time = timeit.default_timer()
for i in range(1000000):
    x = patt.match("test *")
elapsed = timeit.default_timer() - start_time
print "compiled re, true", elapsed

start_time = timeit.default_timer()
for i in range(1000000):
    x = "test 1"[-1] == "*"
elapsed = timeit.default_timer() - start_time
print "char compare, false", elapsed

start_time = timeit.default_timer()
for i in range(1000000):
    x = "test *"[-1] == "*"
elapsed = timeit.default_timer() - start_time
print "char compare, true", elapsed

RESULTS:

re, false 2.4701731205
re, true 2.42048001289
compiled re, false 0.875837087631
compiled re, true 0.876382112503
char compare, false 0.26283121109
char compare, true 0.263465881348

The compiled re is about 3 times as fast as the uncompiled re. The 
character comparison is about 3 times as fast as the compiled re.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From ruudvnrooijen at gmail.com  Tue Nov  3 08:07:37 2015
From: ruudvnrooijen at gmail.com (Ruud van Rooijen)
Date: Tue, 3 Nov 2015 14:07:37 +0100
Subject: python error
Message-ID: <CALAqtxY=u7UA54cBN8wv9OTvVfdKhz_S12UDJqQ+Yq0HDgRe1Q@mail.gmail.com>

my code:

from tkinter import *

window = Tk()
label = Label(window, text="miniproject A1")
label.pack()
window.mainloop()


given error:

C:\Users\Ruud\Python35\Scripts\python.exe
C:/Users/Ruud/PycharmProjects/School/project.py

Traceback (most recent call last):

  File "C:/Users/Ruud/PycharmProjects/School/project.py", line 3, in <module>

    window = Tk()

  File "C:\Users\Ruud\AppData\Local\Programs\Python\Python35-32\Lib\tkinter\__init__.py",
line 1867, in __init__

    self.tk = _tkinter.create(screenName, baseName, className,
interactive, wantobjects, useTk, sync, use)

_tkinter.TclError: Can't find a usable init.tcl in the following directories:

    C:/Users/Ruud/AppData/Local/Programs/Python/Python35-32/lib/tcl8.6
C:/Users/Ruud/Python35/lib/tcl8.6 C:/Users/Ruud/lib/tcl8.6
C:/Users/Ruud/Python35/library C:/Users/Ruud/library
C:/Users/Ruud/tcl8.6.4/library C:/Users/tcl8.6.4/library




This probably means that Tcl wasn't installed properly.


i have repaired python several times and i can't find an answer online...
please help


Ruud


From tjreedy at udel.edu  Tue Nov  3 08:34:35 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 3 Nov 2015 08:34:35 -0500
Subject: python error
In-Reply-To: <CALAqtxY=u7UA54cBN8wv9OTvVfdKhz_S12UDJqQ+Yq0HDgRe1Q@mail.gmail.com>
References: <CALAqtxY=u7UA54cBN8wv9OTvVfdKhz_S12UDJqQ+Yq0HDgRe1Q@mail.gmail.com>
Message-ID: <n1ad5c$osh$1@ger.gmane.org>

On 11/3/2015 8:07 AM, Ruud van Rooijen wrote:
> my code:
>
> from tkinter import *
>
> window = Tk()
> label = Label(window, text="miniproject A1")
> label.pack()
> window.mainloop()
>
>
> given error:
>
> C:\Users\Ruud\Python35\Scripts\python.exe

Based on the below, python.exe should be in
C:\Users\Ruud\AppData\Local\Programs\Python\Python35-32
_tkinter should then be in
C:\Users\Ruud\AppData\Local\Programs\Python\Python35-32\DLLs

If you moved it, that is your problem.

If you have two python installations, with a second one in
C:\Users\Ruud\Python35, then python.exe should be in that directory, NOT 
scripts.

> C:/Users/Ruud/PycharmProjects/School/project.py

I know essentially nothing about PyCharm, even if it is compatible with 
tkinter.

> Traceback (most recent call last):
>
>    File "C:/Users/Ruud/PycharmProjects/School/project.py", line 3, in <module>
>
>      window = Tk()
>
>    File "C:\Users\Ruud\AppData\Local\Programs\Python\Python35-32\Lib\tkinter\__init__.py",
> line 1867, in __init__
>
>      self.tk = _tkinter.create(screenName, baseName, className,
> interactive, wantobjects, useTk, sync, use)
>
> _tkinter.TclError: Can't find a usable init.tcl in the following directories:
>
>      C:/Users/Ruud/AppData/Local/Programs/Python/Python35-32/lib/tcl8.6
> C:/Users/Ruud/Python35/lib/tcl8.6 C:/Users/Ruud/lib/tcl8.6
> C:/Users/Ruud/Python35/library C:/Users/Ruud/library
> C:/Users/Ruud/tcl8.6.4/library C:/Users/tcl8.6.4/library

With a screwed up installation, or pair of installations, it looks 
'everyplace' but the right place.

> This probably means that Tcl wasn't installed properly.

> i have repaired python several times and i can't find an answer online...
> please help

python.exe in scripts is not properly installed.

-- 
Terry Jan Reedy



From nicholas.cole at gmail.com  Tue Nov  3 08:47:47 2015
From: nicholas.cole at gmail.com (Nicholas Cole)
Date: Tue, 3 Nov 2015 13:47:47 +0000
Subject: venv issues
In-Reply-To: <n1a971$isd$1@ger.gmane.org>
References: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
 <n1a971$isd$1@ger.gmane.org>
Message-ID: <CAAu18hcTz0R-Sdqd4BX_dO-630w+XOrzs3KCsK1Xvwuvwa=_Zw@mail.gmail.com>

On Tue, Nov 3, 2015 at 12:27 PM, Wolfgang Maier
<wolfgang.maier at biologie.uni-freiburg.de> wrote:
> On 03.11.2015 11:32, Nicholas Cole wrote:
>>
>> I'm using python3.5 (installed from binaries) on the latest OS X.
>>
>> I have a curious issue with virtual environments on this machine (but
>> not on my other machine).
>>
>>
>> $ python3.5 -m venv testenv
>> $ source testenv/bin/activate
>> (testenv)$ python -m pip
>> /private/tmp/testenv/bin/python: No module named pip
>> $
>>
>> Logging in as a different user and creating a venv works perfectly, so
>> it's clearly a config issue somewhere, but I've tried removing
>> ~/.bashrc and ~/.bash_profile and that doesn't help.
>>
>> The sys.path for that venv is: ['',
>> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python35.zip',
>> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5',
>>
>> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/plat-darwin',
>>
>> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/lib-dynload',
>> '/private/tmp/testenv/lib/python3.5/site-packages']
>>
>
> Is there something special about your /private/tmp folder? In other words,
> do things work if you create a venv in a different place.
> If you go to /private/tmp/testenv/lib/python3.5/site-packages is there a pip
> folder and what are its permission settings?

/private/tmp/testenv/lib/python3.5/site-packages

is completely empty.

There's nothing special about that folder, though. The problem exists
everywhere.


From rosuav at gmail.com  Tue Nov  3 08:59:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 4 Nov 2015 00:59:38 +1100
Subject: venv issues
In-Reply-To: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
References: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
Message-ID: <CAPTjJmq8wPdByPeG391X906E8AAREcz3u0y25Fv3qRz+xgB_=A@mail.gmail.com>

On Tue, Nov 3, 2015 at 9:32 PM, Nicholas Cole <nicholas.cole at gmail.com> wrote:
> Logging in as a different user and creating a venv works perfectly, so
> it's clearly a config issue somewhere, but I've tried removing
> ~/.bashrc and ~/.bash_profile and that doesn't help.

What happens if you create a brand new user, then copy in all
dot-files and directories from your current one? Does it exhibit the
same problem?

ChrisA


From __peter__ at web.de  Tue Nov  3 09:00:48 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 03 Nov 2015 15:00:48 +0100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
 <n19ui8$df7$1@ger.gmane.org> <20151103055018.535e3e42@bigbox.christie.dr>
Message-ID: <n1aemg$hr2$1@ger.gmane.org>

Tim Chase wrote:

> On 2015-11-03 10:25, Peter Otten wrote:
>> >>> How do I make a regular expression that returns true if the end
>> >>> of the line is an asterisk
>> >> 
>> >> Why use a regular expression?
>> >> 
>> >>   if line[-1] == '*':
>> >>     yep(line)
>> >>   else:
>> >>     nope(line)
>> 
>> Incidentally the code example has two "problems", too.
>> 
>> - What about the empty string?
> 
> Good catch: .endswith() works better.
> 
>> - What about lines with a trailing "\n", i. e. as they are usually
>> delivered when iterating over a file?
> 
> Then your string *doesn't* end with a "*", but rather with a
> newline. ;-)
> 
> Though according to the OP's specs, the following function would work
> too:
> 
>   def ends_in_asterisk(s):
>     return True
> 
> It *does* return True if the line ends in an asterisk (no requirement
> to make the function return False under any other conditions).

If a "line" is defined as a string that ends with a newline

def ends_in_asterisk(line):
    return False

would also satisfy the requirement. Lies, damned lies, and specs ;)



From __peter__ at web.de  Tue Nov  3 09:04:27 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 03 Nov 2015 15:04:27 +0100
Subject: venv issues
References: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
Message-ID: <n1aetb$hr2$2@ger.gmane.org>

Nicholas Cole wrote:

> I'm using python3.5 (installed from binaries) on the latest OS X.
> 
> I have a curious issue with virtual environments on this machine (but
> not on my other machine).
> 
> 
> $ python3.5 -m venv testenv
> $ source testenv/bin/activate
> (testenv)$ python -m pip
> /private/tmp/testenv/bin/python: No module named pip
> $
> 
> Logging in as a different user and creating a venv works perfectly, so
> it's clearly a config issue somewhere, but I've tried removing
> ~/.bashrc and ~/.bash_profile and that doesn't help.

Does 

$ which python3.5

(before sourcing bin/activate) point to the same python for both users?

> 
> The sys.path for that venv is: ['',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python35.zip',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/plat-
darwin',
> '/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/lib-
dynload',
> '/private/tmp/testenv/lib/python3.5/site-packages']
> 
> I'm sure I'm overlooking something obvious, but can anyone suggest what?
> 
> Nicholas




From nicholas.cole at gmail.com  Tue Nov  3 09:06:24 2015
From: nicholas.cole at gmail.com (Nicholas Cole)
Date: Tue, 3 Nov 2015 14:06:24 +0000
Subject: venv issues
In-Reply-To: <CAPTjJmq8wPdByPeG391X906E8AAREcz3u0y25Fv3qRz+xgB_=A@mail.gmail.com>
References: <CAAu18hcUPzeLNVziof_b-BRAv-29_M+hNa4SJnYsGTmfL0uLDQ@mail.gmail.com>
 <CAPTjJmq8wPdByPeG391X906E8AAREcz3u0y25Fv3qRz+xgB_=A@mail.gmail.com>
Message-ID: <CAAu18hewBLFHLjXwkPqMi_87gHXxue-YEYZGxHr+H-LMnG=MMQ@mail.gmail.com>

On Tue, Nov 3, 2015 at 1:59 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Nov 3, 2015 at 9:32 PM, Nicholas Cole <nicholas.cole at gmail.com> wrote:
>> Logging in as a different user and creating a venv works perfectly, so
>> it's clearly a config issue somewhere, but I've tried removing
>> ~/.bashrc and ~/.bash_profile and that doesn't help.
>
> What happens if you create a brand new user, then copy in all
> dot-files and directories from your current one? Does it exhibit the
> same problem?

No. And that helped me find the problem.  I had an old

.pydistutils.cfg

file with a line:

install_lib = ~/Library/Python/$py_version_short/lib/python/site-packages

That completely upset the venv.

(whether it should have done or not, I don't know. I would have
expected venv to ignore pydistutils.cfg)

Thank you both for your help!

Best,

N.


From wrw at mac.com  Tue Nov  3 09:45:29 2015
From: wrw at mac.com (William Ray Wing)
Date: Tue, 03 Nov 2015 09:45:29 -0500
Subject: Detection of a specific sound
In-Reply-To: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
Message-ID: <E7CB9062-12AC-4C3D-B3C8-D80B90BB1C56@mac.com>


> On Oct 25, 2015, at 8:17 PM, Montana Burr <montana.burr at gmail.com> wrote:
> 
> I'm looking for a library that will allow Python to listen for the shriek of a smoke alarm. Once it detects this shriek, it is to notify someone. Ideally, specificity can be adjusted for the user's environment. For example, I expect to need moderate specificity as I live in a quiet neighborhood, but an apartment dweller might need more.
> 
> I'm thinking of recording a smoke alarm and having the program try to find the recorded sound in the stream from the microphone.
> 

I?ve been watching this thread and finally decided to jump in.

First off, we REALLY need to know a bit more about what you are trying to accomplish, in what sort of environment, and under what constraints (legal and otherwise).  That last bit is crucial.  Is this simply a heads up e-mail message to be sent or is it a way of notifying a backup (second tier) monitoring service.  Is it for your personal use, or do you expect to sell it (again crucial).  Does the computer you expect to run this on have a good UPS system (in a typical fire, AC power frequently fails early, sometimes it is the *cause* of the fire).  How are you going to get that notification out?  Does your network have battery backup?  Are you going to buy a station-service cell phone transmitter? If you are thinking of sending a cell phone msg, how do you guarantee the receiver is on?  LOTS of issues here.  Then, having said that, and in no particular order:

1) the sounders in most smoke alarms use over-driven pizeo-electric annunciators, their output has a VERY complex frequency spectrum with LOTS of harmonics.  Spectral analysis (combined with threshold analysis) MIGHT be a good way to go, but doing so in real time with Python would consume most, if not all the resources of the host computer;

2) You would (personal opinion), be much better off using hardwired or semi-hardwired detection.  There are several ways to go, including a detector microphone and transmitter such as is used to run a remote doorbell system (mount the microphone next to the smoke detector, then tap into the doorbell receiver box). These have adjustable sensitivity and would basically be a threshold detector.  Alternatively, almost all smoke detectors these days are designed to be chained to each other via three-wire (plus ground) AC wiring.  Two of the wires carry power, the third triggers all the detectors in the system to sound when if of them sound.  Don?t try to tap the signal wire (liability issues), but you could add another detector to the system which would act as your monitor if you tap *its* driver output.

3) Finally, how do you guarantee the computer on which the program is to run will be up at all times?  Does it auto-restart after a power failure, does the program auto-reload as part of the boot-up sequence, and finally, is the program going to have absolutely bullet proof error recovery?

-Bill





> Any help is greatly appreciated!
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From alister.nospam.ware at ntlworld.com  Tue Nov  3 09:49:58 2015
From: alister.nospam.ware at ntlworld.com (alister)
Date: Tue, 3 Nov 2015 14:49:58 +0000 (UTC)
Subject: Detection of a specific sound
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <mailman.1.1446522557.8789.python-list@python.org>
 <n19sgq$ppu$1@speranza.aioe.org>
 <mailman.22.1446559416.8789.python-list@python.org>
Message-ID: <n1ahim$b9l$1@speranza.aioe.org>

On Tue, 03 Nov 2015 09:03:14 -0500, Dennis Lee Bieber wrote:

> On Tue, 3 Nov 2015 08:50:34 +0000 (UTC), alister
> <alister.nospam.ware at ntlworld.com> declaimed the following:
> 
>>Personally I would forget trying to analyse sound & see if there is any
>>way to get an input signal direct from the alarm (even if that is as
>>crude as taking a tap from the siren feed wires)
>>
>>This application sounds far to critical for anything else.
> 
> 	A direct line is what I'd recommend too -- but I'm going to be 
paranoid
> today:
> 
> 	If a fire did occur, and the inspectors find traces of wiring 
going
> into what was supposed to be a stand-alone detector there is a risk that
> it will be concluded that the detector had been tampered with and may
> not have been functional... And that could lead to all sorts of
> liability problems.
> 
> 	I don't know if anyone makes a model that falls between (common)
> stand-alone and full monitored (tied to burglar alarm system with a
> service provider responding to triggers). Something of a monitored type
> (hence designed to be wired to central panel) but without the outside
> monitoring agency.
> 
> 
> 	Barring that... if the detectors are all close in pitch, a PLL 
circuit
> fed from the microphone, using the "locked" signal to indicate when the
> alarm is chirping -- gives a simple on/off digital signal for the
> computer (the computer may be needed to ensure the chirps are at an
> expected rate and not stray whistles). Beyond that, FFT to look for
> spectral signature of chirps.

I would hope that most fire alarm systems (except domestic type smoke 
detectors) would have some relay outputs or telephone dialler options 
which would be legitimate locations to connect extra equipment.

The op probably needs to provide more information on the exact set-up 
intended.



-- 
 ______________________________
/ Gold's Law:                  \
|                              |
\ If the shoe fits, it's ugly. /
 ------------------------------
   \
    \
        .--.
       |o_o |
       |:_/ |
      //   \ \
     (|     | )
    /'\_   _/`\
    \___)=(___/



From invalid at invalid.invalid  Tue Nov  3 09:56:00 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Tue, 3 Nov 2015 14:56:00 +0000 (UTC)
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
Message-ID: <n1ahu0$aur$1@reader1.panix.com>

On 2015-11-03, Tim Chase <python.list at tim.thechases.com> wrote:
> On 2015-11-02 20:09, Seymore4Head wrote:
>> How do I make a regular expression that returns true if the end of
>> the line is an asterisk
>
> Why use a regular expression?
>
>   if line[-1] == '*':

Why use a negative index and then a compare?

    if line.endswith('*'):

If you want to know if a string ends with something, just ask it!
    
;)
    
-- 
Grant Edwards               grant.b.edwards        Yow! RELATIVES!!
                                  at               
                              gmail.com            


From random832 at fastmail.com  Tue Nov  3 09:57:34 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 03 Nov 2015 09:57:34 -0500
Subject: Detection of a specific sound
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <mailman.1.1446522557.8789.python-list@python.org>
 <n19sgq$ppu$1@speranza.aioe.org>
 <s1fh3bljdbvdkovgd2vk1cevdfggbvbgsj@4ax.com>
Message-ID: <878u6f9llt.fsf@fastmail.com>

Dennis Lee Bieber <wlfraed at ix.netcom.com> writes:

> If a fire did occur, and the inspectors find traces of wiring
> going into what was supposed to be a stand-alone detector there is
> a risk that it will be concluded that the detector had been
> tampered with and may not have been functional... And that could
> lead to all sorts of liability problems.

What about a *second* smoke detector?



From random832 at fastmail.com  Tue Nov  3 10:00:33 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 03 Nov 2015 10:00:33 -0500
Subject: Unbuffered stderr in Python 3
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
Message-ID: <874mh39lgu.fsf@fastmail.com>

Nobody <nobody at nowhere.invalid> writes:

> It's probably related to the fact that std{in,out,err} are Unicode
> streams. 

There's no fundamental reason a Unicode stream should have to be line
buffered. If it's "related", it's only in that an oversight was made in
the course of making that change.



From harvesting at makes.email.invalid  Tue Nov  3 10:12:28 2015
From: harvesting at makes.email.invalid (Jussi Piitulainen)
Date: Tue, 03 Nov 2015 17:12:28 +0200
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
Message-ID: <lf5io5junfn.fsf@ling.helsinki.fi>

Peter Otten writes:

> If a "line" is defined as a string that ends with a newline
>
> def ends_in_asterisk(line):
>     return False
>
> would also satisfy the requirement. Lies, damned lies, and specs ;)

Even if a "line" is defined as a string that comes from reading
something like a file with default options, a line may end in
an asterisk.

>>> [ line.endswith('*') for line in StringIO('rivi*\nrivi*\nrivi*') ]
[False, False, True]


From joel.goldstick at gmail.com  Tue Nov  3 10:34:12 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Tue, 3 Nov 2015 10:34:12 -0500
Subject: Regular expressions
In-Reply-To: <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
Message-ID: <CAPM-O+wiVqgGFPywy0=5rBDAV4D69b=EdaEQu7g7_QfiajRsjw@mail.gmail.com>

On Mon, Nov 2, 2015 at 10:17 PM, Seymore4Head <Seymore4Head at hotmail.invalid>
wrote:

> On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
> <python.list at tim.thechases.com> wrote:
>
> >On 2015-11-02 20:09, Seymore4Head wrote:
> >> How do I make a regular expression that returns true if the end of
> >> the line is an asterisk
> >
> >Why use a regular expression?
> >
> >  if line[-1] == '*':
> >    yep(line)
> >  else:
> >    nope(line)
> >
> >-tkc
> >
> >
> Because that is the part of Python I am trying to learn at the moment.
>

Are we to infer that you were aware of doing the   if line[-1] == '*': ...
, but just wanted to learn how to do the same thing with regex? Or that you
heard about regexes and thought that would be the way to solve your puzzle?

> Thanks
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From __peter__ at web.de  Tue Nov  3 10:35:22 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 03 Nov 2015 16:35:22 +0100
Subject: Irregular last line in a text file, was Re: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
 <n19ui8$df7$1@ger.gmane.org> <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi>
Message-ID: <n1ak7u$jgs$1@ger.gmane.org>

Jussi Piitulainen wrote:

> Peter Otten writes:
> 
>> If a "line" is defined as a string that ends with a newline
>>
>> def ends_in_asterisk(line):
>>     return False
>>
>> would also satisfy the requirement. Lies, damned lies, and specs ;)
> 
> Even if a "line" is defined as a string that comes from reading
> something like a file with default options, a line may end in
> an asterisk.
 
Note that the last line from the file is not a line as defined by me in the 
above post ;)

>>>> [ line.endswith('*') for line in StringIO('rivi*\nrivi*\nrivi*') ]
> [False, False, True]

I wish there were a way to prohibit such files. Maybe a special value

with open(..., newline="normalize") f: 
    assert all(line.endswith("\n") for line in f)

to ensure that all lines end with "\n"?




From rosuav at gmail.com  Tue Nov  3 10:42:19 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 4 Nov 2015 02:42:19 +1100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <874mh39lgu.fsf@fastmail.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
Message-ID: <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>

On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com> wrote:
> Nobody <nobody at nowhere.invalid> writes:
>
>> It's probably related to the fact that std{in,out,err} are Unicode
>> streams.
>
> There's no fundamental reason a Unicode stream should have to be line
> buffered. If it's "related", it's only in that an oversight was made in
> the course of making that change.

Yep. Unicode *input* streams need to be buffered, but *output* can
always be insta-flushed. The only significance of Unicode to output is
that a single character may cause multiple bytes to be output; and
since output can block for even a single byte, it should be no
different.

+1 for making sys.stderr unbuffered.

ChrisA


From oscar.j.benjamin at gmail.com  Tue Nov  3 10:52:27 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 3 Nov 2015 15:52:27 +0000
Subject: LU decomposition
In-Reply-To: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
References: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
Message-ID: <CAHVvXxSktSENzWdiE933iK7ZF019R9j-AHMmLk190942V3=0Zw@mail.gmail.com>

On 1 November 2015 at 10:04, gers antifx <schweiger.gerald at gmail.com> wrote:
>
> I have to write a LU-decomposition. My Code worked so far but (I want to become better:) ) I want to ask you, if I could write this LU-decomposition in a better way?
>
> def LU(x):
>     L = np.eye((x.shape[0]))
>     n = x.shape[0]
>     for ii in range(n-1):
>         for ll in range(1+ii,n):
>             factor = float(x[ll,ii])/x[ii,ii]
>             L[ll,ii] = factor
>             for kk in range(0+ii,n):
>                     x[ll,kk] = x[ll,kk] - faktor*x[ii,kk]
>     LU = np.dot(L,x)

You're using ii and ll, kk etc. This is common practise in Matlab code
because Matlab uses i as sqrt(-1) but this is spelled 1j in Python so
we don't have that problem. In this sort of context it would be more
natural to use simply i, j, k in Python.

Another is that you're not checking for divide by zero in
float(x[ll,ii])/x[ii,ii]. Are you sure that it will not be zero? What
happens if e.g. x[0, 0] is zero? This is where you'll need to use
pivoting which complicates the algorithm a bit.

--
Oscar


From kwpolska at gmail.com  Tue Nov  3 11:01:42 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Tue, 3 Nov 2015 17:01:42 +0100
Subject: Python PNG Viewer(Browser Based)
In-Reply-To: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
References: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
Message-ID: <CAMw+j7KgU1258x_sVU7NjALezEQq3+9jhu_m2fudO3rJ351y9w@mail.gmail.com>

On 3 November 2015 at 12:54, Arshpreet Singh <arsh840 at gmail.com> wrote:
> Hello Everyone,
>
> I am looking for Browser-based PNG file viewer written in
> Python.(Flask framework preferably)
>
> Following project(Flask-Based) provides many things(File manager as
> well as file viewer)  but it does not support PNG files.
>
> https://github.com/vmi356/filemanager
>
> Any idea if I have to write my own browser based PNG viewer from
> scratch(Using PIL or other required library)
>
> On the other side if I have to write only Desktop-based only two lines
> are enough to do many things:
>
> Like,
>
> from PIL import Image
> f = Image.open("file.png").show()
>
>
> But I am not getting right sense that how to make possible using Python+Flask.
>
> Hope I am able to tell my problem?
> --
> https://mail.python.org/mailman/listinfo/python-list

Your problem is lack of basic understanding of the Internet. Because
EVERY graphical web browser supports PNG files NATIVELY. With a single
<img> tag.

Just figure out where to add the PNG handler code and read any random
?how to add images to a webpage? tutorial.
You might need a new template and some code that is aware of the file
being an image. But absolutely no PNG viewer is necessary.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From Seymore4Head at Hotmail.invalid  Tue Nov  3 11:10:20 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Tue, 03 Nov 2015 11:10:20 -0500
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.28.1446564855.8789.python-list@python.org>
Message-ID: <tjmh3blsb60fmvginp4q6sbe2659p4rh9f@4ax.com>

On Tue, 3 Nov 2015 10:34:12 -0500, Joel Goldstick
<joel.goldstick at gmail.com> wrote:

>On Mon, Nov 2, 2015 at 10:17 PM, Seymore4Head <Seymore4Head at hotmail.invalid>
>wrote:
>
>> On Mon, 2 Nov 2015 20:42:37 -0600, Tim Chase
>> <python.list at tim.thechases.com> wrote:
>>
>> >On 2015-11-02 20:09, Seymore4Head wrote:
>> >> How do I make a regular expression that returns true if the end of
>> >> the line is an asterisk
>> >
>> >Why use a regular expression?
>> >
>> >  if line[-1] == '*':
>> >    yep(line)
>> >  else:
>> >    nope(line)
>> >
>> >-tkc
>> >
>> >
>> Because that is the part of Python I am trying to learn at the moment.
>>
>
>Are we to infer that you were aware of doing the   if line[-1] == '*': ...
>, but just wanted to learn how to do the same thing with regex? Or that you
>heard about regexes and thought that would be the way to solve your puzzle?
>
>> Thanks
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
Yes I knew that -1 represents the end character.  It is not a question
of trying to accomplish anything.  I was just practicing with regex
and wasn't sure how to express a * since it was one of the
instructions.



From rosuav at gmail.com  Tue Nov  3 11:20:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 4 Nov 2015 03:20:04 +1100
Subject: Regular expressions
In-Reply-To: <tjmh3blsb60fmvginp4q6sbe2659p4rh9f@4ax.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.28.1446564855.8789.python-list@python.org>
 <tjmh3blsb60fmvginp4q6sbe2659p4rh9f@4ax.com>
Message-ID: <CAPTjJmrgvULUf9kRf1=3VJYSGT9fK4gF0Pe--o23gi9QZFU0gg@mail.gmail.com>

On Wed, Nov 4, 2015 at 3:10 AM, Seymore4Head
<Seymore4Head at hotmail.invalid> wrote:
> Yes I knew that -1 represents the end character.  It is not a question
> of trying to accomplish anything.  I was just practicing with regex
> and wasn't sure how to express a * since it was one of the
> instructions.

In that case, it's nothing to do with ending a string. What you really
want to know is: How do you match a '*' using a regular expression?
Which is what MRAB answered, courtesy of a working crystal ball: You
use '\*'. Everything about the end of the string is irrelevant. (So,
too, are all the comments about using [-1] or string methods. But we
weren't to know that.)

ChrisA


From ian.g.kelly at gmail.com  Tue Nov  3 11:23:46 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 3 Nov 2015 09:23:46 -0700
Subject: Detection of a specific sound
In-Reply-To: <E7CB9062-12AC-4C3D-B3C8-D80B90BB1C56@mac.com>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <E7CB9062-12AC-4C3D-B3C8-D80B90BB1C56@mac.com>
Message-ID: <CALwzidkZnERs6ccmZyeurdCCRF_b61+62S0dfYFuH2Cp8x++GA@mail.gmail.com>

On Tue, Nov 3, 2015 at 7:45 AM, William Ray Wing <wrw at mac.com> wrote:
>
>> On Oct 25, 2015, at 8:17 PM, Montana Burr <montana.burr at gmail.com> wrote:
>>
>> I'm looking for a library that will allow Python to listen for the shriek of a smoke alarm. Once it detects this shriek, it is to notify someone. Ideally, specificity can be adjusted for the user's environment. For example, I expect to need moderate specificity as I live in a quiet neighborhood, but an apartment dweller might need more.
>>
>> I'm thinking of recording a smoke alarm and having the program try to find the recorded sound in the stream from the microphone.
>>
>
> I?ve been watching this thread and finally decided to jump in.

I love how in the past 24 hours five more people have piled onto this
thread even though the OP hasn't posted any followup since the
original question nine days ago.


From marco.nawijn at colosso.nl  Tue Nov  3 11:25:45 2015
From: marco.nawijn at colosso.nl (marco.nawijn at colosso.nl)
Date: Tue, 3 Nov 2015 08:25:45 -0800 (PST)
Subject: Python PNG Viewer(Browser Based)
In-Reply-To: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
References: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
Message-ID: <5732e5a4-23d4-43df-8af7-41be14ab37dc@googlegroups.com>

On Tuesday, November 3, 2015 at 12:55:09 PM UTC+1, Arshpreet Singh wrote:
> Hello Everyone,
> 
> I am looking for Browser-based PNG file viewer written in
> Python.(Flask framework preferably)
> 
> Following project(Flask-Based) provides many things(File manager as
> well as file viewer)  but it does not support PNG files.
> 
> https://github.com/vmi356/filemanager
> 
> Any idea if I have to write my own browser based PNG viewer from
> scratch(Using PIL or other required library)
> 
> On the other side if I have to write only Desktop-based only two lines
> are enough to do many things:
> 
> Like,
> 
> from PIL import Image
> f = Image.open("file.png").show()
> 
> 
> But I am not getting right sense that how to make possible using Python+Flask.
> 
> Hope I am able to tell my problem?

Well, if you only want to open the PNG file in the webbrowser
(in contrast of serving them over the internet), you can do it
in two lines too:

import webbrowser
webbrowser.open('file.png')

But this is probably not what you want.

M.


From harvesting at makes.email.invalid  Tue Nov  3 11:42:20 2015
From: harvesting at makes.email.invalid (Jussi Piitulainen)
Date: Tue, 03 Nov 2015 18:42:20 +0200
Subject: Irregular last line in a text file, was Re: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi>
 <mailman.29.1446564939.8789.python-list@python.org>
Message-ID: <lf5bnbbxcer.fsf@ling.helsinki.fi>

Peter Otten writes:
> Jussi Piitulainen wrote:
>> Peter Otten writes:
>> 
>>> If a "line" is defined as a string that ends with a newline
>>>
>>> def ends_in_asterisk(line):
>>>     return False
>>>
>>> would also satisfy the requirement. Lies, damned lies, and specs ;)
>> 
>> Even if a "line" is defined as a string that comes from reading
>> something like a file with default options, a line may end in
>> an asterisk.
>  
> Note that the last line from the file is not a line as defined by me
> in the above post ;)

Noted.

>>>>> [ line.endswith('*') for line in StringIO('rivi*\nrivi*\nrivi*') ]
>> [False, False, True]
>
> I wish there were a way to prohibit such files. Maybe a special value
>
> with open(..., newline="normalize") f: 
>     assert all(line.endswith("\n") for line in f)
>
> to ensure that all lines end with "\n"?

I'd like that. It should be the default.


From joel.goldstick at gmail.com  Tue Nov  3 11:55:53 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Tue, 3 Nov 2015 11:55:53 -0500
Subject: Detection of a specific sound
In-Reply-To: <CALwzidkZnERs6ccmZyeurdCCRF_b61+62S0dfYFuH2Cp8x++GA@mail.gmail.com>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <E7CB9062-12AC-4C3D-B3C8-D80B90BB1C56@mac.com>
 <CALwzidkZnERs6ccmZyeurdCCRF_b61+62S0dfYFuH2Cp8x++GA@mail.gmail.com>
Message-ID: <CAPM-O+x3RNEXRwBzE4xP9qJGxhpasW059JLRn+tG4QC8WZ-ShQ@mail.gmail.com>

On Tue, Nov 3, 2015 at 11:23 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:

> On Tue, Nov 3, 2015 at 7:45 AM, William Ray Wing <wrw at mac.com> wrote:
> >
> >> On Oct 25, 2015, at 8:17 PM, Montana Burr <montana.burr at gmail.com>
> wrote:
> >>
> >> I'm looking for a library that will allow Python to listen for the
> shriek of a smoke alarm. Once it detects this shriek, it is to notify
> someone. Ideally, specificity can be adjusted for the user's environment.
> For example, I expect to need moderate specificity as I live in a quiet
> neighborhood, but an apartment dweller might need more.
> >>
> >> I'm thinking of recording a smoke alarm and having the program try to
> find the recorded sound in the stream from the microphone.
> >>
> >
> > I?ve been watching this thread and finally decided to jump in.
>
> I love how in the past 24 hours five more people have piled onto this
> thread even though the OP hasn't posted any followup since the
> original question nine days ago.
> --
> https://mail.python.org/mailman/listinfo/python-list
>

Sometimes (maybe most times) the follow on discussion goes off on
insightful tangents that may have little to do with the OP.

-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From python.list at tim.thechases.com  Tue Nov  3 11:56:53 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 3 Nov 2015 10:56:53 -0600
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <n1ak7u$jgs$1@ger.gmane.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
Message-ID: <20151103105653.622d5e34@bigbox.christie.dr>

On 2015-11-03 16:35, Peter Otten wrote:
> I wish there were a way to prohibit such files. Maybe a special
> value
> 
> with open(..., newline="normalize") f: 
>     assert all(line.endswith("\n") for line in f)
> 
> to ensure that all lines end with "\n"?

Or even more valuable to me:

  with open(..., newline="strip") as f:
    assert all(not line.endswith(("\n", "\r")) for line in f)

because I have countless loops that look something like

  with open(...) as f:
    for line in f:
      line = line.rstrip('\r\n')
      process(line)

-tkc






From israel at ravnalaska.net  Tue Nov  3 12:05:19 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Tue, 3 Nov 2015 08:05:19 -0900
Subject: CherryPy cpstats and ws4py
Message-ID: <ADF91099-857B-47E0-93F0-6A68E33E8F68@ravnalaska.net>

I posted this to the CherryPy and ws4py mailing lists, but in the week since I did that I've only gotten two or three views on each list, and no responses, so as a last-ditch effort I thought I'd post here. Maybe someone with more general python knowledge than me can figure out the traceback and from there a solution.

Is it possible to use ws4py in conjunction with the cpstats CherryPy tool? I have a CherryPy (3.8.0) web app that uses web sockets via ws4py. Tested and working. I am now trying to get a little more visibility into the functioning of the server, so to that end I enabled the cpstats tool by adding the following line to my '/' configuration:

tools.cpstats.on=True

Unfortunately, as soon as I do that, attempts to connect a web socket start failing with the following traceback:

[28/Oct/2015:08:18:48]  
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 104, in run
    hook()
  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 63, in __call__
    return self.callback(**self.kwargs)
  File "build/bdist.macosx-10.10-intel/egg/ws4py/server/cherrypyserver.py", line 200, in upgrade
    ws_conn = get_connection(request.rfile.rfile)
  File "build/bdist.macosx-10.10-intel/egg/ws4py/compat.py", line 43, in get_connection
    return fileobj._sock
AttributeError: 'KnownLengthRFile' object has no attribute '_sock'
[28/Oct/2015:08:18:48] HTTP 
Request Headers:
  PRAGMA: no-cache
  COOKIE: autoTabEnabled=true; fleetStatusFilterCompany=7H; fleetStatusFilterLocation=ALL; fleetStatusRefreshInterval=5; inputNumLegs=5; session_id=5c8303896aff419c175c79dfadbfdc9d75e6c45a
  UPGRADE: websocket
  HOST: flbubble.ravnalaska.net:8088
  ORIGIN: http://flbubble.ravnalaska.net
  CONNECTION: Upgrade
  CACHE-CONTROL: no-cache
  SEC-WEBSOCKET-VERSION: 13
  SEC-WEBSOCKET-EXTENSIONS: x-webkit-deflate-frame
  USER-AGENT: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/601.2.7 (KHTML, like Gecko) Version/9.0.1 Safari/601.2.7
  SEC-WEBSOCKET-KEY: Szh6Uoe+WzqKR1DgW8JcXA==
  Remote-Addr: 10.9.1.59
[28/Oct/2015:08:18:48] HTTP 
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 661, in respond
    self.hooks.run('before_request_body')
  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 114, in run
    raise exc
AttributeError: 'KnownLengthRFile' object has no attribute '_sock'

Disable tools.cpstats.on, and the sockets start working again. Is there some way I can fix this so I can use sockets as well as gather stats from my application? Thanks.

-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------



From gandalf at shopzeus.com  Tue Nov  3 12:35:43 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Tue, 3 Nov 2015 18:35:43 +0100
Subject: pybabel extraction mess
Message-ID: <5638F06F.4010902@shopzeus.com>

If I have a large project with multiple directories, then I may want to
assign different translation domains for different subpackages.

Suppose I have this directory structure:

main
   |
   |--- sub1
   |
   |--- sub2
            |
            |---- sub2.1
            |
            |---- sub2.2

There are python source files in subpackages, and also at upper level
packages. Some examples:

main/test1.py
main/sub1/test2.py
main/sub2/test3.py
main/sub2/sub2.1/test4.py
main/sub2/sub2.2/test5.py
....


I cannot find out how to run pybabel so that messages from different
subdirectories gets extracted into different catalog files. The main
problem is that pybabel expects a directory. Let's say that I want to
have a different domain for main/sub2/sub2.1, and another domain for
everything else.

I can extract messages from main/sub/sub2.1 with "pybabel extract
main/sub/sub2.1", but I'm not able to extract all the others into a
different pot file. Simply because "pybabel extract main" will extract
all messages from main/sub2/sub2.1 again. There is no way to extract
from a list of files. Just from directories. It does not seem possible
to specify disjunct sets of files for message catalogs.

For a small project, this is not a problem. If I have at least one file
at the main level, then all other files MUST be bound to the same
domain, because the top level file can only be extracted by giving the
top directory to pybabel, but that will also extract everything else
from the whole project.

I would really like to divide messages into different domains. But how?
Is there a way to run pybabel programatically on a list of source files?

Thanks,

   Laszlo




From __peter__ at web.de  Tue Nov  3 12:44:36 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 03 Nov 2015 18:44:36 +0100
Subject: Irregular last line in a text file, was Re: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
 <n19ui8$df7$1@ger.gmane.org> <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <20151103105653.622d5e34@bigbox.christie.dr>
Message-ID: <n1arq4$qok$1@ger.gmane.org>

Tim Chase wrote:

> On 2015-11-03 16:35, Peter Otten wrote:
>> I wish there were a way to prohibit such files. Maybe a special
>> value
>> 
>> with open(..., newline="normalize") f:
>>     assert all(line.endswith("\n") for line in f)
>> 
>> to ensure that all lines end with "\n"?
> 
> Or even more valuable to me:
> 
>   with open(..., newline="strip") as f:
>     assert all(not line.endswith(("\n", "\r")) for line in f)
> 
> because I have countless loops that look something like
> 
>   with open(...) as f:
>     for line in f:
>       line = line.rstrip('\r\n')
>       process(line)

Indeed. It's obvious now you're saying it...



From george.trojan at noaa.gov  Tue Nov  3 13:03:51 2015
From: george.trojan at noaa.gov (George Trojan)
Date: Tue, 03 Nov 2015 18:03:51 +0000
Subject: Unbuffered stderr in Python 3
In-Reply-To: <mailman.30.1446570002.25765.python-list@python.org>
References: <mailman.30.1446570002.25765.python-list@python.org>
Message-ID: <5638F707.90309@noaa.gov>

On 11/03/2015 05:00 PM, python-list-request at python.org wrote:
> On Mon, 02 Nov 2015 18:52:55 +1100, Steven D'Aprano wrote:
>
>> In Python 2, stderr is unbuffered.
>>
>> In most other environments (the shell, C...) stderr is unbuffered.
>>
>> It is usually considered a bad, bad thing for stderr to be buffered. What
>> happens if your application is killed before the buffer fills up? The
>> errors in the buffer will be lost.
>>
>> So how come Python 3 has line buffered stderr? And more importantly, how
>> can I turn buffering off?
> It's probably related to the fact that std{in,out,err} are Unicode
> streams.
>
> 	> type(sys.stderr)
> 	<class '_io.TextIOWrapper'>
> 	> type(sys.stderr.buffer)
> 	<class '_io.BufferedWriter'>
> 	> type(sys.stderr.buffer.raw)
> 	<class '_io.FileIO'>
>
> It appears that you can turn it off with:
>
> 	sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
> or:
> 	sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach())
>
> This results in a sys.stderr which appears to work and whose
> .line_buffering property is False.
>
>
This does set line buffering, but does not change the behaviour:

(devenv-3.4.1) dilbert at gtrojan> cat x.py
import sys
import time
if sys.version>'3':
     import io
     sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach())
     #sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
     print(sys.stderr.line_buffering)
sys.stderr.write('a')
time.sleep(10)

This is python2.7.5. a is printed before ^C.

(devenv-3.4.1) dilbert at gtrojan> /bin/python x.py
a^CTraceback (most recent call last):

Here buffer is flushed on close, after typing ^C.

(devenv-3.4.1) dilbert at gtrojan> python x.py
False
^CaTraceback (most recent call last):

George


From esawiek at gmail.com  Tue Nov  3 13:18:49 2015
From: esawiek at gmail.com (Ek Esawi)
Date: Tue, 3 Nov 2015 13:18:49 -0500
Subject: cvxopt install problem
Message-ID: <CA+ZkTxvx22y7CbqWWG7zWVUd3Px0thHBUGyVhfYmBVKDhqs2eQ@mail.gmail.com>

Hi All?





I needed to install cvxopt on a 64 bit W7. I found out that cvxopt is
incompatible with a 64 bit. It only compatible with a 32 bit which can be
installed on a 64 bit computer and it works. I stumbled on this on another
discussion group posting. The suggestion was to install python 32 bit on a
64 bit computer, then download cvxopt and install it via conda.



Here is the suggestion from the posting  [If you are using Windows, an easy
solution could be the Anaconda distribution (http://continuum.io/downloads).
Select and install the 32 bit version. It will be easier to install the
cvxopt package. Search it in the binstar repository (
https://binstar.org/search?q=cvxopt). Open a console terminal and install
it (e. g. "conda install -chttps://conda.binstar.org/omnia cvxopt").?]



I did everything except the last command to install cvxopt, that?s ?conda
install -chttps://conda.binstar.org/omnia cvxopt".

Here is the command I used:

conda install c:/Users/eesawi0001/Downloads/cvxopt-1.1.7-py34.tar

I kept getting invalid syntax



Any help is greatly appreciated.


EKE


From gandalf at shopzeus.com  Tue Nov  3 13:21:33 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Tue, 3 Nov 2015 19:21:33 +0100
Subject: LU decomposition
In-Reply-To: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
References: <1e6c4ce1-885c-43ac-b0a5-054f46d4c96e@googlegroups.com>
Message-ID: <5638FB2D.3060307@shopzeus.com>


> Hey,
>
> I have to write a LU-decomposition. My Code worked so far but (I want to become better:) ) I want to ask you, if I could write this LU-decomposition in a better way?
Why can't you just use scipy for this?

http://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.linalg.lu.html

Do you really need to reinvent the wheel?




From george.trojan at noaa.gov  Tue Nov  3 13:31:32 2015
From: george.trojan at noaa.gov (George Trojan)
Date: Tue, 03 Nov 2015 18:31:32 +0000
Subject: Unbuffered stderr in Python 3
In-Reply-To: <5638F707.90309@noaa.gov>
References: <5638F707.90309@noaa.gov>
Message-ID: <5638FD84.3060402@noaa.gov>




-------- Forwarded Message --------
Subject: 	Re: Unbuffered stderr in Python 3
Date: 	Tue, 03 Nov 2015 18:03:51 +0000
From: 	George Trojan <george.trojan at noaa.gov>
To: 	python-list at python.org



On 11/03/2015 05:00 PM, python-list-request at python.org wrote:
> On Mon, 02 Nov 2015 18:52:55 +1100, Steven D'Aprano wrote:
>
>> In Python 2, stderr is unbuffered.
>>
>> In most other environments (the shell, C...) stderr is unbuffered.
>>
>> It is usually considered a bad, bad thing for stderr to be buffered. What
>> happens if your application is killed before the buffer fills up? The
>> errors in the buffer will be lost.
>>
>> So how come Python 3 has line buffered stderr? And more importantly, how
>> can I turn buffering off?
> It's probably related to the fact that std{in,out,err} are Unicode
> streams.
>
> 	> type(sys.stderr)
> 	<class '_io.TextIOWrapper'>
> 	> type(sys.stderr.buffer)
> 	<class '_io.BufferedWriter'>
> 	> type(sys.stderr.buffer.raw)
> 	<class '_io.FileIO'>
>
> It appears that you can turn it off with:
>
> 	sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
> or:
> 	sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach())
>
> This results in a sys.stderr which appears to work and whose
> .line_buffering property is False.
>
>
This does set line buffering, but does not change the behaviour:

(devenv-3.4.1) dilbert at gtrojan> cat x.py
import sys
import time
if sys.version>'3':
     import io
     sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach())
     #sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
     print(sys.stderr.line_buffering)
sys.stderr.write('a')
time.sleep(10)

This is python2.7.5. a is printed before ^C.

(devenv-3.4.1) dilbert at gtrojan> /bin/python x.py
a^CTraceback (most recent call last):

Here buffer is flushed on close, after typing ^C.//

(devenv-3.4.1) dilbert at gtrojan> python x.py
False
^CaTraceback (most recent call last):

George

Found it. write_through must be set to True.

(devenv-3.4.1) dilbert at gtrojan> cat x.py
import sys
import time
if sys.version>'3':
     import io
     sys.stderr = io.TextIOWrapper(sys.stderr.detach().detach(), 
write_through=True)
     #sys.stderr = io.TextIOWrapper(sys.stderr.buffer.raw)
     print(sys.stderr.line_buffering)
sys.stderr.write('a')
time.sleep(10)
(devenv-3.4.1) dilbert at gtrojan> python x.py
False
a^CTraceback (most recent call last):

/

/


From ian.g.kelly at gmail.com  Tue Nov  3 13:33:55 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 3 Nov 2015 11:33:55 -0700
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <20151103105653.622d5e34@bigbox.christie.dr>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi>
 <n1ak7u$jgs$1@ger.gmane.org> <20151103105653.622d5e34@bigbox.christie.dr>
Message-ID: <CALwzidn4e_8_LuuzgiS-vQWUZG+WS0cXmy2-kzpXHBLuPqN53Q@mail.gmail.com>

On Tue, Nov 3, 2015 at 9:56 AM, Tim Chase <python.list at tim.thechases.com> wrote:
> On 2015-11-03 16:35, Peter Otten wrote:
>> I wish there were a way to prohibit such files. Maybe a special
>> value
>>
>> with open(..., newline="normalize") f:
>>     assert all(line.endswith("\n") for line in f)
>>
>> to ensure that all lines end with "\n"?
>
> Or even more valuable to me:
>
>   with open(..., newline="strip") as f:
>     assert all(not line.endswith(("\n", "\r")) for line in f)
>
> because I have countless loops that look something like
>
>   with open(...) as f:
>     for line in f:
>       line = line.rstrip('\r\n')
>       process(line)

What would happen if you read a file opened like this without
iterating over lines?


From ian.g.kelly at gmail.com  Tue Nov  3 13:39:32 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 3 Nov 2015 11:39:32 -0700
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <CALwzidn4e_8_LuuzgiS-vQWUZG+WS0cXmy2-kzpXHBLuPqN53Q@mail.gmail.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi>
 <n1ak7u$jgs$1@ger.gmane.org> <20151103105653.622d5e34@bigbox.christie.dr>
 <CALwzidn4e_8_LuuzgiS-vQWUZG+WS0cXmy2-kzpXHBLuPqN53Q@mail.gmail.com>
Message-ID: <CALwzidmJV4=kbi-m+pT43k=b7DTbfMr77HN2EDsRQrG6_dKxbg@mail.gmail.com>

On Tue, Nov 3, 2015 at 11:33 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Tue, Nov 3, 2015 at 9:56 AM, Tim Chase <python.list at tim.thechases.com> wrote:
>> Or even more valuable to me:
>>
>>   with open(..., newline="strip") as f:
>>     assert all(not line.endswith(("\n", "\r")) for line in f)
>>
>> because I have countless loops that look something like
>>
>>   with open(...) as f:
>>     for line in f:
>>       line = line.rstrip('\r\n')
>>       process(line)
>
> What would happen if you read a file opened like this without
> iterating over lines?

I think I'd go with this:

>>> def strip_newlines(iterable):
...     for line in iterable:
...         yield line.rstrip('\r\n')
...
>>> list(strip_newlines(['one\n', 'two\r', 'three']))
['one', 'two', 'three']

Or if I care about optimizing the for loop (but we're talking about
file I/O, so probably not), this might be faster:

>>> import operator
>>> def strip_newlines(iterable):
...     return map(operator.methodcaller('rstrip', '\r\n'), iterable)
...
>>> list(strip_newlines(['one\n', 'two\r', 'three']))
['one', 'two', 'three']

Then the iteration is just:
    for line in strip_newlines(f):


From anthony at cajuntechie.org  Tue Nov  3 14:09:06 2015
From: anthony at cajuntechie.org (Anthony Papillion)
Date: Tue, 03 Nov 2015 13:09:06 -0600
Subject: Creating PST files using Python 
Message-ID: <873907D8-7E21-4F08-AF07-A83F766802BA@cajuntechie.org>

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Does anyone know of a module that allows the wiring of Outlook PST files using Python? I'm working on a project that will require me to migrate 60gb of maildir mail (multiple accounts) to Outlook.

Thanks
Anthony
- --
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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From random832 at fastmail.com  Tue Nov  3 14:45:11 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 03 Nov 2015 14:45:11 -0500
Subject: Unbuffered stderr in Python 3
References: <mailman.30.1446570002.25765.python-list@python.org>
 <5638F707.90309@noaa.gov>
Message-ID: <87pozqvpdk.fsf@fastmail.com>

George Trojan <george.trojan at noaa.gov> writes:
> This does set line buffering, but does not change the behaviour:

The opposite of line buffering is not no buffering, but full
(i.e. block) buffering, that doesn't get flushed until it runs
out of space. TextIOWrapper has its own internal buffer, and its
design apparently doesn't contemplate the possibility of using
it with a raw FileIO object (which may mean that the posted code
isn't guaranteed to work) or disabling buffering.



From python.list at tim.thechases.com  Tue Nov  3 14:45:47 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 3 Nov 2015 13:45:47 -0600
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <CALwzidmJV4=kbi-m+pT43k=b7DTbfMr77HN2EDsRQrG6_dKxbg@mail.gmail.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <20151103105653.622d5e34@bigbox.christie.dr>
 <CALwzidn4e_8_LuuzgiS-vQWUZG+WS0cXmy2-kzpXHBLuPqN53Q@mail.gmail.com>
 <CALwzidmJV4=kbi-m+pT43k=b7DTbfMr77HN2EDsRQrG6_dKxbg@mail.gmail.com>
Message-ID: <20151103134547.3556cc74@bigbox.christie.dr>

On 2015-11-03 11:39, Ian Kelly wrote:
> >> because I have countless loops that look something like
> >>
> >>   with open(...) as f:
> >>     for line in f:
> >>       line = line.rstrip('\r\n')
> >>       process(line)  
> >
> > What would happen if you read a file opened like this without
> > iterating over lines?  
> 
> I think I'd go with this:
> 
> >>> def strip_newlines(iterable):  
> ...     for line in iterable:
> ...         yield line.rstrip('\r\n')
> ...

Behind the scenes, this is what I usually end up doing, but the
effective logic is the same.  I just like the notion of being able to
tell open() that I want iteratation to happen over the *content* of
the lines, ignoring the new-line delimiters.

I can't think of more than 1-2 times in my last 10+ years of
Pythoning that I've actually had potential use for the newlines,
usually on account of simply feeding the entire line back into some
filelike.write() method where I wanted the newlines in the resulting
file. But even in those cases, I seem to recall stripping off the
arbitrary newlines (LF vs. CR/LF) and then adding my own known line
delimiter.

-tkc





From no.email at nospam.invalid  Tue Nov  3 14:59:24 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Tue, 03 Nov 2015 11:59:24 -0800
Subject: Modern recommended exception handling practices?
References: <52739457-5f7a-48ea-8835-9fc8934174f9@googlegroups.com>
 <56385887$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <mailman.7.1446534982.8789.python-list@python.org>
Message-ID: <87h9l2yhur.fsf@nightsong.com>

Chris Angelico <rosuav at gmail.com> writes:
> Aside from string exceptions and the "except Type, e:" syntax, I would
> agree with you. Actually, I can't think of any "obsolete
> exception-handling practices" in any language. 

I'd say that context managers are a big recent improvement in Python
over dealing with a lot of exceptions explicitly.


From rosuav at gmail.com  Tue Nov  3 17:12:45 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 4 Nov 2015 09:12:45 +1100
Subject: Creating PST files using Python
In-Reply-To: <873907D8-7E21-4F08-AF07-A83F766802BA@cajuntechie.org>
References: <873907D8-7E21-4F08-AF07-A83F766802BA@cajuntechie.org>
Message-ID: <CAPTjJmrVrLYrFvHuMR1Sjv59D_8UAA_wovKBRXfEdnU3oTPCPQ@mail.gmail.com>

On Wed, Nov 4, 2015 at 6:09 AM, Anthony Papillion
<anthony at cajuntechie.org> wrote:
> Does anyone know of a module that allows the wiring of Outlook PST files using Python? I'm working on a project that will require me to migrate 60gb of maildir mail (multiple accounts) to Outlook.
>

*wince*

I don't, but if there is such a thing, it'll probably be mentioned here:

https://pypi.python.org

But be careful. My gut feeling is that the format will be different in
every version of Outlook, so you'll need something exactly matching
it.

Since you're migrating your mail *to* Outlook, I'd look for some means
of importing mail. Worst case, you could create a bunch of files in
the maildir layout, spin up an off-the-shelf POP3 server, and tell
Outlook to read it all.

Personally, though, I'd refuse the job altogether. Creating a 60GB
blob of mail is going to cause nothing but pain. That might even be
beyond Outlook's current hard limit - I don't know. Bad, bad idea.

ChrisA


From invalid at invalid.invalid  Tue Nov  3 17:15:58 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Tue, 3 Nov 2015 22:15:58 +0000 (UTC)
Subject: Irregular last line in a text file, was Re: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
 <n19ui8$df7$1@ger.gmane.org> <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <20151103105653.622d5e34@bigbox.christie.dr>
 <CALwzidn4e_8_LuuzgiS-vQWUZG+WS0cXmy2-kzpXHBLuPqN53Q@mail.gmail.com>
 <CALwzidmJV4=kbi-m+pT43k=b7DTbfMr77HN2EDsRQrG6_dKxbg@mail.gmail.com>
 <mailman.48.1446581076.8789.python-list@python.org>
Message-ID: <n1bbmu$qse$1@reader1.panix.com>

On 2015-11-03, Tim Chase <python.list at tim.thechases.com> wrote:

[re. iterating over lines in a file]

> I can't think of more than 1-2 times in my last 10+ years of
> Pythoning that I've actually had potential use for the newlines,

If you can think of 1-2 times when you've been interating over the
lines in a file and wanted to see the EOL markers, then that's 1-2
times more than I've ever wanted to see them since I started using
Python 16 years ago...

-- 
Grant Edwards               grant.b.edwards        Yow! !  Up ahead!  It's a
                                  at               DONUT HUT!!
                              gmail.com            


From tjreedy at udel.edu  Tue Nov  3 17:25:55 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 3 Nov 2015 17:25:55 -0500
Subject: Unbuffered stderr in Python 3
In-Reply-To: <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
Message-ID: <n1bc9j$c6e$1@ger.gmane.org>

On 11/3/2015 10:42 AM, Chris Angelico wrote:
> On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com> wrote:
>> Nobody <nobody at nowhere.invalid> writes:
>>
>>> It's probably related to the fact that std{in,out,err} are Unicode
>>> streams.
>>
>> There's no fundamental reason a Unicode stream should have to be line
>> buffered. If it's "related", it's only in that an oversight was made in
>> the course of making that change.

The current behavior is not an 'oversight'.  I was considered, decided, 
and revisited in https://bugs.python.org/issue13601.  Guido: 
"Line-buffering should be good enough since in practice errors messages 
are always terminated by a newline."  If not, print(part_line, 
file=sys.stderr, flush=True) works for the unusual case.

> Yep. Unicode *input* streams need to be buffered, but *output* can
> always be insta-flushed. The only significance of Unicode to output is
> that a single character may cause multiple bytes to be output; and
> since output can block for even a single byte, it should be no
> different.
>
> +1 for making sys.stderr unbuffered.

-
Terry Jan Reedy



From robin.koch at t-online.de  Tue Nov  3 17:58:33 2015
From: robin.koch at t-online.de (Robin Koch)
Date: Tue, 3 Nov 2015 23:58:33 +0100
Subject: Regular expressions
In-Reply-To: <0cb3abb6-ec1e-4357-ab0f-b018d0c688fa@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <mailman.2.1446522680.8789.python-list@python.org>
 <0cb3abb6-ec1e-4357-ab0f-b018d0c688fa@googlegroups.com>
Message-ID: <n1be6n$6rf$1@news.albasani.net>

Am 03.11.2015 um 05:23 schrieb rurpy at yahoo.com:

> Of course there are people who misuse regexes.

/^1?$|^(11+?)\1+$/

There are? 0:-)

-- 
Robin Koch


From cs at zip.com.au  Tue Nov  3 19:10:23 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Wed, 4 Nov 2015 11:10:23 +1100
Subject: Creating PST files using Python
In-Reply-To: <CAPTjJmrVrLYrFvHuMR1Sjv59D_8UAA_wovKBRXfEdnU3oTPCPQ@mail.gmail.com>
References: <CAPTjJmrVrLYrFvHuMR1Sjv59D_8UAA_wovKBRXfEdnU3oTPCPQ@mail.gmail.com>
Message-ID: <20151104001023.GA79983@cskk.homeip.net>

On 04Nov2015 09:12, Chris Angelico <rosuav at gmail.com> wrote:
>On Wed, Nov 4, 2015 at 6:09 AM, Anthony Papillion
><anthony at cajuntechie.org> wrote:
>> Does anyone know of a module that allows the wiring of Outlook PST files using Python? I'm working on a project that will require me to migrate 60gb of maildir mail (multiple accounts) to Outlook.
>
>*wince*
>
>I don't, but if there is such a thing, it'll probably be mentioned here:
>https://pypi.python.org
>
>But be careful. My gut feeling is that the format will be different in
>every version of Outlook, so you'll need something exactly matching
>it.

Microsoft have a page here:

  https://msdn.microsoft.com/en-us/library/ff385210%28v=office.12%29.aspx

which purports to document the PST format. There are links to the document 
sections and also to PDFs.

It seems to be a simple and understandable format of a mere 190 pages. Yes, I 
am joking, though not about the page count; it seems like an obscene and 
totally nuts way to store email. IIRC, M$ LookOut! doesn't even use 
Message-IDs, but some proprietry scheme.

>Since you're migrating your mail *to* Outlook, I'd look for some means
>of importing mail. Worst case, you could create a bunch of files in
>the maildir layout,

The OP has these I think.

>spin up an off-the-shelf POP3 server, and tell
>Outlook to read it all.
>
>Personally, though, I'd refuse the job altogether. Creating a 60GB
>blob of mail is going to cause nothing but pain. That might even be
>beyond Outlook's current hard limit - I don't know. Bad, bad idea.

It is a very strange request. But very corporate/government in mindset.

Alas, I cannot help to the with any tools or module for his task.

Cheers,
Cameron Simpson <cs at zip.com.au>

Microsoft Mail: as far from RFC-822 as you can get and still pretend to care.
        - Abby Franquemont-Guillory <abbyfg at tezcat.com>


From rurpy at yahoo.com  Tue Nov  3 19:22:53 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Tue, 3 Nov 2015 16:22:53 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <56385efc$0$1598$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <455b6498-5104-491a-98c2-6f7e48142496@googlegroups.com>

On 11/03/2015 12:15 AM, Steven D'Aprano wrote:
> On Tue, 3 Nov 2015 03:23 pm, rurpy wrote:
> 
>> Regular expressions should be learned by every programmer or by anyone
>> who wants to use computers as a tool.  They are a fundamental part of
>> computer science and are used in all sorts of matching and searching
>> from compilers down to your work-a-day text editor.
> 
> You are absolutely right.
> 
> If only regular expressions weren't such an overly-terse, cryptic
> mini-language, with all but no debugging capabilities, they would be great.
> 
> If only there wasn't an extensive culture of regular expression abuse within
> programming communities, they would be fine.
> 
> All technologies are open to abuse. But we don't say:
> 
>   Some people, when confronted with a problem, think "I know, I'll use
>   arithmetic." Now they have two problems.
> 
> because abuse of arithmetic is rare. It's hard to misuse it, and while
> arithmetic can be complicated, it's rare for programmers to abuse it. But
> the same cannot be said for regexes -- they are regularly misused, abused,
> and down-right hard to use right even when you have a good reason for using
> them:
> 
> http://www.thedailywtf.com/articles/Irregular_Expression
> 
> http://blog.codinghorror.com/regex-use-vs-regex-abuse/
> 
> http://psung.blogspot.com.au/2008/01/wonderful-abuse-of-regular-expressions.html

Thanks for pointing out three cases of misuse of regexes out of the
approximately 375000000 [*] uses of regexes in the wild. I hope you're
not dumb enough to think that constitutes significant evidence.

Even worse, of the three only one was a real example. One of the others
was machine-generated code, the other was a "look what you can do with
regexes" example, not serious code.

Here is an example of "abusing" python

  https://benkurtovic.com/2014/06/01/obfuscating-hello-world.html

I wouldn't use this as evidence that Python is to be avoided.

> If there is one person who has done more to create a regex culture, it is
> Larry Wall, inventor of Perl. Even Larry Wall says that regexes are
> overused and their syntax is harmful, and he has recreated them for Perl 6:
> 
> http://www.perl.com/pub/2002/06/04/apo5.html

You really should have read beyond the first paragraph. He proposes
fixing regexes by adding even more special character combinations and
making regexes even *more* powerful. (He turned them into full-blown
parsers.)

Nowhere does he advocate not using, or avoiding if possible, regexes
as is the mantra in this list.

Here is Larry's "recreation" that you are touting:

  http://design.perl6.org/S05.html

Please explain to us how you think this "fix" addresses the complaints
you and other Python anti-regexers have about regexes.

I hope you also noted Larry's tongue-in-cheek writing style. Right after
pointing out that some claim Perl is hard to read due largely to regex
syntax, he writes:

  "Funny that other languages have been borrowing Perl's regular
  expressions as fast as they can..."

So I don't think you can claim Larry Wall as a supporter of this list's
anti-regex attitude beyond some superficial verbiage taken out of context.

> Oh, and the icing on the cake, regexes can be a security vulnerability too:
> https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS

And here is a list of CVEs involving Python. There are (at time of
writing) 190 of them.

  http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=python

So if a security vulnerability is reason not to use regexes, we should
all be *running* from Python. I sure you'll point out that most have
been fixed.

But you failed to point out that same is true of regex engines. From
your source:

  "Notice, that not all algorithms are na?ve, and actually Regex
  algorithms can be written in an efficient way."

And in fact, again, had you looked beyond a headline that suited your
purpose, you could have tried the "Evil Regexes" noted in that source
and discovered none of them are a DoS in Python.

Even were that not true, normal practice applies: if the input is
untrusted then sanitize it, or mitigate the threat by imposing a timeout,
etc. Not exactly a problem or solution unique to regexes. And common
sense should tell you that since there are a lot of "try a regex" web
sites, this is not a problem without a solution.

And *certainly* not a reason not to use them in the *far* more common
case when they *are* trusted because you are in control of them,

Finally, preemptively, I'll repeat I acknowledge regexs are not the
the optimum solution in every case where they could be used. But they
are very useful when one passes the border of the trivial; and they are
nowhere near as bad as routinely portrayed here.

----
[*] Yes, I made that number up.


From rurpy at yahoo.com  Tue Nov  3 19:33:17 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Tue, 3 Nov 2015 16:33:17 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.5.1446525488.8789.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
Message-ID: <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>

On Monday, November 2, 2015 at 9:38:24 PM UTC-7, Michael Torrie wrote:
> On 11/02/2015 09:23 PM, rurpy--- via Python-list wrote:
> >> My completely unsolicited advice is that regular expressions shouldn't be
> >> very high on the list of things to learn.  They are very useful, and very
> >> tricky and prone many problems that can and should be learned to be
> >> resolved with much simpler methods.  If you really want to learn regular
> >> expressions, that's great but the problem you posed is not one for which
> >> they are the best solution.  Remember simpler is better than complex.
> > 
> > Regular expressions should be learned by every programmer or by anyone
> > who wants to use computers as a tool.  They are a fundamental part of
> > computer science and are used in all sorts of matching and searching 
> > from compilers down to your work-a-day text editor.
> > 
> > Not knowing how to use them is like an auto mechanic not knowing how to 
> > use a socket wrench.
> 
> Not quite.  Core language concepts like ifs, loops, functions,
> variables, slicing, etc are the socket wrenches of the programmer's
> toolbox.  Regexs are like an electric impact socket wrench.  You can do
> the same work without it, but in many cases it's slower. But you have to
> learn the other hand tools first in order to really use the electric
> driver properly (understanding torques, direction of threads, etc), lest
> you wonder why you're breaking off so many bolts with the torque of the
> impact drive.

I consider regexs more fundemental.  One need not even be a programmer
to use them: consider grep, sed, a zillion editors, database query 
languages, etc.

When there is a mini-language explicitly developed for describing
string patterns, why, except is very simple cases, would one not
take advantage of it?  Beyond trivial operations a regex, although
terse (overly perhaps), is still likely to be more understandable 
more maintainable than bunch of ad-hoc code.  And the relative ease 
of expressing complex patterns means one is more likely to create
more specific patterns, resulting in detecting unexpected input 
earlier than with ad-hoc code. 


From rurpy at yahoo.com  Tue Nov  3 19:46:21 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Tue, 3 Nov 2015 16:46:21 -0800 (PST)
Subject: Creating PST files using Python
In-Reply-To: <mailman.46.1446578069.8789.python-list@python.org>
References: <mailman.46.1446578069.8789.python-list@python.org>
Message-ID: <0ba52316-7f52-4314-a454-0a5d369feed6@googlegroups.com>

On 11/03/2015 12:09 PM, Anthony Papillion wrote:
> Does anyone know of a module that allows the wiring of Outlook PST
> files using Python? I'm working on a project that will require me to
> migrate 60gb of maildir mail (multiple accounts) to Outlook.

I used libpst (http://www.five-ten-sg.com/libpst/) a few years ago
successfully but I was going in the other direction (outlook -> maildir)
so not sure if it does writing of pst files. 
At the time I also looked into libpff which (from my notes, I don't
remember much of this work) was newer but the documentation was pretty
thin and it wasn't worth the time to figure out how to use it.
Of course things may have changed since then...



From dpantele at dpantele.com  Tue Nov  3 20:24:04 2015
From: dpantele at dpantele.com (Dmitry Panteleev)
Date: Tue, 3 Nov 2015 20:24:04 -0500
Subject: Bugfixing python 3.5 asyncio
Message-ID: <CA+eiJG2Puii8xmVjK9vZF_XrKwNrTaiYNqtrzHk8uakGpu8AYA@mail.gmail.com>

Hello,

There is a bug in asyncio.Queue
(https://github.com/python/asyncio/issues/268), which makes it
unusable for us. It is fixed in master now. What is the easiest way to
patch the asyncio bundled with python if I have to distribute it among
5 colleagues? It is used in our private module.

I can think of:
1. Copy asyncio.queues into our package so it has a different name
2. Override sys.path

Both look really strange. Is there anything else?

Thanks,
Dmitry Panteleev


From rurpy at yahoo.com  Tue Nov  3 20:32:11 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Tue, 3 Nov 2015 17:32:11 -0800 (PST)
Subject: Creating PST files using Python
In-Reply-To: <0ba52316-7f52-4314-a454-0a5d369feed6@googlegroups.com>
References: <mailman.46.1446578069.8789.python-list@python.org>
 <0ba52316-7f52-4314-a454-0a5d369feed6@googlegroups.com>
Message-ID: <b12fcea5-6e46-41c5-ba54-6d06ec5cbf1f@googlegroups.com>

I should have checked the web site before posting, it
appears that both libpst and libpff only read pst files,
no write.  Sorry for the noise.


From torriem at gmail.com  Tue Nov  3 21:04:23 2015
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 03 Nov 2015 19:04:23 -0700
Subject: Regular expressions
In-Reply-To: <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
Message-ID: <563967A7.4060308@gmail.com>

On 11/03/2015 05:33 PM, rurpy--- via Python-list wrote:
> I consider regexs more fundemental.  One need not even be a programmer
> to use them: consider grep, sed, a zillion editors, database query 
> languages, etc.

Grep can use regular expressions (and I do so with it regularly), but
it's default mode is certainly not regular expressions, and it is still
very powerful.  I've never used regular expressions in a database query
language; until this moment I didn't know any supported such things in
their queries.  Good to know.  How you would index for regular
expressions in queries I don't know.

> When there is a mini-language explicitly developed for describing
> string patterns, why, except is very simple cases, would one not
> take advantage of it?  

Mainly because the programming language itself often can do it just as
cleanly and just as fast (slicing, string methods, etc).  I certainly
programmed for many years without needing regular expressions in my
small projects.  In fact, REs are a bit of a pain to use in, say, C or
C++, requiring a library.  With Python they are much more readily
accessible so I use them much more.

But honestly it wasn't until college when I learned about finite state
automata that I really grasped what regular expressions were and how to
use them.

> Beyond trivial operations a regex, although
> terse (overly perhaps), is still likely to be more understandable 
> more maintainable than bunch of ad-hoc code.  And the relative ease 
> of expressing complex patterns means one is more likely to create
> more specific patterns, resulting in detecting unexpected input 
> earlier than with ad-hoc code. 

Maybe, maybe not.  Using Python string class methods is probably more
clear when such methods are sufficient.



From dan at tombstonezero.net  Tue Nov  3 21:55:12 2015
From: dan at tombstonezero.net (Dan Sommers)
Date: Wed, 4 Nov 2015 02:55:12 -0000 (UTC)
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
Message-ID: <n1bs2g$376$1@dont-email.me>

On Tue, 03 Nov 2015 19:04:23 -0700, Michael Torrie wrote:

> On 11/03/2015 05:33 PM, rurpy--- via Python-list wrote:
>> I consider regexs more fundemental.  One need not even be a programmer
>> to use them: consider grep, sed, a zillion editors, database query 
>> languages, etc.
> 
> Grep can use regular expressions (and I do so with it regularly), but
> it's default mode is certainly not regular expressions ...

Its very name indicates that its default mode most certainly is regular
expressions.

Dan


From python.list at tim.thechases.com  Tue Nov  3 22:12:08 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Tue, 3 Nov 2015 21:12:08 -0600
Subject: Regular expressions
In-Reply-To: <563967A7.4060308@gmail.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <563967A7.4060308@gmail.com>
Message-ID: <20151103211208.2a7ec561@bigbox.christie.dr>

On 2015-11-03 19:04, Michael Torrie wrote:
> Grep can use regular expressions (and I do so with it regularly),
> but it's default mode is certainly not regular expressions, and it
> is still very powerful.

I suspect you're thinking of `fgrep` (AKA "grep -F") which uses fixed
strings rather than regular expressions.  By default, `grep` certainly
does use regular expressions:

  tim at linux$ seq 5 | grep "1*"
  tim at bsd$ jot 5 | grep "1*"

will output the entire input, not just lines containing a "1"
followed by an asterisk.

> I've never used regular expressions in a database query language;
> until this moment I didn't know any supported such things in their
> queries.  Good to know.  How you would index for regular
> expressions in queries I don't know.

At least PostgreSQL allows for creating indexes on a particular
regular expression.  E.g. (shooting from the hip so I might have
missed something):

  CREATE TABLE contacts (
   -- ...
   phonenumber VARCHAR(15),
   -- ...
   )
  CREATE INDEX contacts_just_phone_digits_idx
   ON contacts((regexp_replace(phonenumber, '[^0-9]', '')));

  INSERT INTO contacts(..., phonenumber, ...)
   VALUES (..., '800-555-1212', ...)

  SELECT *
  FROM contacts
  WHERE -- should use contacts_just_phone_digits_idx
   regexp_replace(phonenumber, '[^0-9]', '') = '8005551212';

It's not as helpful as one might hope because you're stuck using a
fixed regexp rather than an arbitrary regexp, but if you have a
particular regexp you search for frequently, you can index it.
Otherwise, you'd be doing full table-scans (or at least a full scan
of whatever subset the active non-regexp'ed index yields) which can
be pretty killer on performance.

You'd have to research on other DB engines.

-tkc






From steve+comp.lang.python at pearwood.info  Tue Nov  3 22:18:55 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 14:18:55 +1100
Subject: Unbuffered stderr in Python 3
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
Message-ID: <56397921$0$11094$c3e8da3@news.astraweb.com>

On Wednesday 04 November 2015 09:25, Terry Reedy wrote:

> On 11/3/2015 10:42 AM, Chris Angelico wrote:
>> On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com> wrote:
>>> Nobody <nobody at nowhere.invalid> writes:
>>>
>>>> It's probably related to the fact that std{in,out,err} are Unicode
>>>> streams.
>>>
>>> There's no fundamental reason a Unicode stream should have to be line
>>> buffered. If it's "related", it's only in that an oversight was made in
>>> the course of making that change.
> 
> The current behavior is not an 'oversight'.  I was considered, decided,
> and revisited in https://bugs.python.org/issue13601.  Guido:
> "Line-buffering should be good enough since in practice errors messages
> are always terminated by a newline."  If not, print(part_line,
> file=sys.stderr, flush=True) works for the unusual case.

This is one of the offending line from our code base:

print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)

So that ought to be terminated by a newline. And yet, the stderr output 
doesn't show up until the program exits.




-- 
Steve



From steve+comp.lang.python at pearwood.info  Tue Nov  3 22:23:04 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 14:23:04 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
Message-ID: <56397a18$0$11094$c3e8da3@news.astraweb.com>

On Wednesday 04 November 2015 13:55, Dan Sommers wrote:

> On Tue, 03 Nov 2015 19:04:23 -0700, Michael Torrie wrote:
> 
>> On 11/03/2015 05:33 PM, rurpy--- via Python-list wrote:
>>> I consider regexs more fundemental.  One need not even be a programmer
>>> to use them: consider grep, sed, a zillion editors, database query
>>> languages, etc.
>> 
>> Grep can use regular expressions (and I do so with it regularly), but
>> it's default mode is certainly not regular expressions ...
> 
> Its very name indicates that its default mode most certainly is regular
> expressions.

I don't even know what grep stands for. 

But I think what Michael may mean is that if you "grep foo", no regex magic 
takes place since "foo" contains no metacharacters.




-- 
Steven



From rosuav at gmail.com  Tue Nov  3 22:26:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 4 Nov 2015 14:26:42 +1100
Subject: Regular expressions
In-Reply-To: <20151103211208.2a7ec561@bigbox.christie.dr>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <563967A7.4060308@gmail.com>
 <20151103211208.2a7ec561@bigbox.christie.dr>
Message-ID: <CAPTjJmqQLCEzv_0FcyTT=jWhkhATd9wJzno3TfPCUyMESUn61w@mail.gmail.com>

On Wed, Nov 4, 2015 at 2:12 PM, Tim Chase <python.list at tim.thechases.com> wrote:
> It's not as helpful as one might hope because you're stuck using a
> fixed regexp rather than an arbitrary regexp, but if you have a
> particular regexp you search for frequently, you can index it.
> Otherwise, you'd be doing full table-scans (or at least a full scan
> of whatever subset the active non-regexp'ed index yields) which can
> be pretty killer on performance.

If the regex anchors the start of the string, you can generally use an
index to save at least some effort. Otherwise, you're relying on some
kind of alternate indexing style, such as:

http://www.postgresql.org/docs/current/static/pgtrgm.html

which specifically mentions regex searches as being indexable.

Some more info, including 'explain' results:

http://www.depesz.com/2013/04/10/waiting-for-9-3-support-indexing-of-regular-expression-searches-in-contribpg_trgm/

But this kind of thing isn't widely supported across databases.

ChrisA


From steve+comp.lang.python at pearwood.info  Tue Nov  3 22:35:23 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 14:35:23 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.28.1446564855.8789.python-list@python.org>
 <tjmh3blsb60fmvginp4q6sbe2659p4rh9f@4ax.com>
 <mailman.34.1446567607.8789.python-list@python.org>
Message-ID: <56397cfd$0$1601$c3e8da3$5496439d@news.astraweb.com>

On Wednesday 04 November 2015 03:20, Chris Angelico wrote:

> On Wed, Nov 4, 2015 at 3:10 AM, Seymore4Head
> <Seymore4Head at hotmail.invalid> wrote:
>> Yes I knew that -1 represents the end character.  It is not a question
>> of trying to accomplish anything.  I was just practicing with regex
>> and wasn't sure how to express a * since it was one of the
>> instructions.
> 
> In that case, it's nothing to do with ending a string. 

Seymore never said anything about ending a string.


> What you really
> want to know is: How do you match a '*' using a regular expression?

He may want to know that too, but that's not what he asked for. He asked how 
to match an asterisk at the end of the line.


> Which is what MRAB answered, courtesy of a working crystal ball: You
> use '\*'. Everything about the end of the string is irrelevant.

Not at all -- matching "\*" will find lines *beginning* with an asterisk if 
you use re.match, and lines containing an asterisk *anywhere* in the line if 
you use re.search.

I say "line" because the most common use for re.match and re.search is to 
match against a single line of text, but of course regexes can operate on 
multiline blocks of text, with or without multiline mode turned on.

And calling it "a working crystal ball" is somewhat of an exaggeration. The 
plain English meaning of Seymore's plain English question is easily 
understood: he wants to know how to match an asterisk at the end of the 
line, just like he said :-P


> (So,
> too, are all the comments about using [-1] or string methods. But we
> weren't to know that.)

If MRAB could understand what he wanted, I'm sure most others could have 
too.



-- 
Steve



From steve+comp.lang.python at pearwood.info  Tue Nov  3 22:39:04 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 14:39:04 +1100
Subject: Irregular last line in a text file, was Re: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr> <56382F33.8050905@gmail.com>
 <n19ui8$df7$1@ger.gmane.org> <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <mailman.37.1446569907.8789.python-list@python.org>
Message-ID: <56397dd9$0$1601$c3e8da3$5496439d@news.astraweb.com>

On Wednesday 04 November 2015 03:56, Tim Chase wrote:

> Or even more valuable to me:
> 
>   with open(..., newline="strip") as f:
>     assert all(not line.endswith(("\n", "\r")) for line in f)

# Works only on Windows text files.
def chomp(lines):
    for line in lines:
        yield line.rstrip('\r\n')


Better would be this:

def chomp(lines):
    for line in lines:
        yield line.rstrip()  # remove all trailing whitespace


with open(...) as f:
    for line in chomp(f): ...


-- 
Steve



From torriem at gmail.com  Tue Nov  3 22:47:18 2015
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 03 Nov 2015 20:47:18 -0700
Subject: Regular expressions
In-Reply-To: <56397a18$0$11094$c3e8da3@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <56397FC6.9040700@gmail.com>

On 11/03/2015 08:23 PM, Steven D'Aprano wrote:
>>> Grep can use regular expressions (and I do so with it regularly), but
>>> it's default mode is certainly not regular expressions ...
>>
>> Its very name indicates that its default mode most certainly is regular
>> expressions.
> 
> I don't even know what grep stands for. 
> 
> But I think what Michael may mean is that if you "grep foo", no regex magic 
> takes place since "foo" contains no metacharacters.

More likely I just don't know what I'm talking about.  I must have been
thinking about something else (shell globbing perhaps).

Certainly most of the times I've seen grep used, it's to look for a word
with no special metacharacters, as you say. Still a valid RE of course.
 But I have learned to night I don't need to resort to grep -e to use
regular expressions.  At least with GNU grep, that's the default.


From steve+comp.lang.python at pearwood.info  Tue Nov  3 22:48:21 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 14:48:21 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
Message-ID: <56398006$0$11100$c3e8da3@news.astraweb.com>

On Wednesday 04 November 2015 11:33, rurpy at yahoo.com wrote:

>> Not quite.  Core language concepts like ifs, loops, functions,
>> variables, slicing, etc are the socket wrenches of the programmer's
>> toolbox.  Regexs are like an electric impact socket wrench.  You can do
>> the same work without it, but in many cases it's slower. But you have to
>> learn the other hand tools first in order to really use the electric
>> driver properly (understanding torques, direction of threads, etc), lest
>> you wonder why you're breaking off so many bolts with the torque of the
>> impact drive.
> 
> I consider regexs more fundemental

I'm sure that there are people who consider the International Space Station 
more fundamental than the lever, the wedge and the hammer, but they would be 
wrong too.

Given primitives for branching, loops and variables, you can build support 
for regexes. Given regexes, how would you build support for variables?

Of course, you could easily prove me wrong. All you would need to do to 
demonstrate that regexes are more fundamental than branching, loops and 
variables would be to demonstrate that the primitive operations available in 
commonly used CPUs are regular expressions, and that (for example) C's for 
loop and if...else are implemented in machine code as regular expressions, 
rather than the other way around.



-- 
Steve



From nobody at nowhere.invalid  Wed Nov  4 00:05:53 2015
From: nobody at nowhere.invalid (Nobody)
Date: Wed, 04 Nov 2015 05:05:53 +0000
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <pan.2015.11.04.05.05.52.633000@nowhere.invalid>

On Wed, 04 Nov 2015 14:23:04 +1100, Steven D'Aprano wrote:

>> Its very name indicates that its default mode most certainly is regular
>> expressions.
> 
> I don't even know what grep stands for.

>From the ed command "g /re/p" (where "re" is a placeholder for an
arbitrary regular expression). Tests all lines ("g" for global) against
the specified regexp and prints ("p") any which match.

> But I think what Michael may mean is that if you "grep foo", no regex
> magic takes place since "foo" contains no metacharacters.

At least the GNU version will treat the input as a regexp regardless of
whether it contains only literal characters. I.e. "grep foo" and
"grep [f][o][o]" will both construct the same state machine then process
the input with it.

You need to actually use -F to change the matching algorithm.



From arsh840 at gmail.com  Wed Nov  4 01:27:51 2015
From: arsh840 at gmail.com (Arshpreet Singh)
Date: Tue, 3 Nov 2015 22:27:51 -0800 (PST)
Subject: Python PNG Viewer(Browser Based)
In-Reply-To: <mailman.33.1446566504.8789.python-list@python.org>
References: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
 <mailman.33.1446566504.8789.python-list@python.org>
Message-ID: <f20799fe-6c23-4417-b5ae-d2acd75fa3ce@googlegroups.com>

On Tuesday, 3 November 2015 21:32:03 UTC+5:30, Chris Warrick  wrote:
> On 3 November 2015 at 12:54, Arshpreet Singh <arsh840 at gmail.com> wrote:
> > Hello Everyone,
> >
> > I am looking for Browser-based PNG file viewer written in
> > Python.(Flask framework preferably)
> >
> > Following project(Flask-Based) provides many things(File manager as
> > well as file viewer)  but it does not support PNG files.
> >
> > https://github.com/vmi356/filemanager
> >
> > Any idea if I have to write my own browser based PNG viewer from
> > scratch(Using PIL or other required library)
> >
> > On the other side if I have to write only Desktop-based only two lines
> > are enough to do many things:
> >
> > Like,
> >
> > from PIL import Image
> > f = Image.open("file.png").show()
> >
> >
> > But I am not getting right sense that how to make possible using Python+Flask.
> >
> > Hope I am able to tell my problem?
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Your problem is lack of basic understanding of the Internet. 

Yes That's true at some level.

>Because
> EVERY graphical web browser supports PNG files NATIVELY. With a single
> <img> tag.

That is easily understandable. 
 
> Just figure out where to add the PNG handler code and read any random
> "how to add images to a webpage" tutorial.
> You might need a new template and some code that is aware of the file
> being an image. But absolutely no PNG viewer is necessary.

My present working system shows me list of all files (PNGs, JPGs, txt, SVGs) in browser, when I click on file it opens it and show contents of it. but PNG and JPGs are not working. Surely handling one PNG file is easy but no idea how to solve multiple file situation.


From auriocus at gmx.de  Wed Nov  4 02:21:45 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 4 Nov 2015 08:21:45 +0100
Subject: Regular expressions
In-Reply-To: <56398006$0$11100$c3e8da3@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
Message-ID: <n1cbi4$ao5$1@dont-email.me>

Am 04.11.15 um 04:48 schrieb Steven D'Aprano:
> On Wednesday 04 November 2015 11:33, rurpy at yahoo.com wrote:
>
>>> Not quite.  Core language concepts like ifs, loops, functions,
>>> variables, slicing, etc are the socket wrenches of the programmer's
>>> toolbox.  Regexs are like an electric impact socket wrench.  You can do
>>> the same work without it, but in many cases it's slower. But you have to
>>> learn the other hand tools first in order to really use the electric
>>> driver properly (understanding torques, direction of threads, etc), lest
>>> you wonder why you're breaking off so many bolts with the torque of the
>>> impact drive.
>>
>> I consider regexs more fundemental
>
> I'm sure that there are people who consider the International Space Station
> more fundamental than the lever, the wedge and the hammer, but they would be
> wrong too.
>
> Given primitives for branching, loops and variables, you can build support
> for regexes. Given regexes, how would you build support for variables?
>
> Of course, you could easily prove me wrong.

You *know* that they are not equivalent, I assume? regexes are 
equivalent to finite state machines, which are less powerful than Turing 
machines, and even less powerful than stack machines. You can't even 
construct a regexp which validates, if parentheses are balanced.

What rurpy meant, was that regexes can surface to a computer user 
earlier than variables and branches; a user who does not go into the 
depth to actually program the machine, might still encounter them in a 
text editor or database engine. Even some web forms allow some limited 
form, like e.g. the DVD rental here or Google.

	Christian


From ben+python at benfinney.id.au  Wed Nov  4 02:23:53 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 04 Nov 2015 18:23:53 +1100
Subject: Python PNG Viewer(Browser Based)
References: <9c24559b-17a4-41fc-80a2-9258fd84c9f1@googlegroups.com>
 <mailman.33.1446566504.8789.python-list@python.org>
 <f20799fe-6c23-4417-b5ae-d2acd75fa3ce@googlegroups.com>
Message-ID: <85bnbakz1y.fsf@benfinney.id.au>

Arshpreet Singh <arsh840 at gmail.com> writes:

> On Tuesday, 3 November 2015 21:32:03 UTC+5:30, Chris Warrick  wrote:
> > Your problem is lack of basic understanding of the Internet. 
>
> Yes That's true at some level.

More specifically, your problem is not ?how do I do this with Python??
but rather ?what is a web page??.

So, the research you need to do is not Python-specific, instead you need
to learn about the structure of web pages and web applications.

> My present working system shows me list of all files (PNGs, JPGs, txt,
> SVGs) in browser, when I click on file it opens it and show contents
> of it.

You are directing your web browser to visit a folder on your local file
system. It is obliging you by presenting a directory of local files.

Instead, you need to learn how to author web pages.

There are countless resources for learning about generating a web page
from scratch. You could learn a lot from the Wikibooks project
<URL:https://en.wikibooks.org/wiki/Authoring_Webpages>.

You'll also need to appreciate that developing web pages is a *very*
extensive topic. You might need nothing more than to create simple
static pages; you don't need Python at all for that. You might need a
powerful Web programming framework, Python has excellent support for
that <URL:https://wiki.python.org/moin/WebFrameworks>.

Without you learning the very basics of web sites, though, you won't get
much use from Python-specific knowledge about web frameworks.

Good hunting!

-- 
 \              ?Ridicule is the only weapon which can be used against |
  `\       unintelligible propositions.? ?Thomas Jefferson, 1816-07-30 |
_o__)                                                                  |
Ben Finney



From wolfgang.maier at biologie.uni-freiburg.de  Wed Nov  4 03:19:42 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Wed, 4 Nov 2015 09:19:42 +0100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <56397921$0$11094$c3e8da3@news.astraweb.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <n1cf2u$d7v$1@ger.gmane.org>

On 04.11.2015 04:18, Steven D'Aprano wrote:
> On Wednesday 04 November 2015 09:25, Terry Reedy wrote:
>
>> On 11/3/2015 10:42 AM, Chris Angelico wrote:
>>> On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com> wrote:
>>>> Nobody <nobody at nowhere.invalid> writes:
>>>>
>>>>> It's probably related to the fact that std{in,out,err} are Unicode
>>>>> streams.
>>>>
>>>> There's no fundamental reason a Unicode stream should have to be line
>>>> buffered. If it's "related", it's only in that an oversight was made in
>>>> the course of making that change.
>>
>> The current behavior is not an 'oversight'.  I was considered, decided,
>> and revisited in https://bugs.python.org/issue13601.  Guido:
>> "Line-buffering should be good enough since in practice errors messages
>> are always terminated by a newline."  If not, print(part_line,
>> file=sys.stderr, flush=True) works for the unusual case.
>
> This is one of the offending line from our code base:
>
> print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)
>
> So that ought to be terminated by a newline. And yet, the stderr output
> doesn't show up until the program exits.
>

For me, that prints immediately. Where is your output going? Console, 
file, ...?



From fabien.maussion at gmail.com  Wed Nov  4 03:39:09 2015
From: fabien.maussion at gmail.com (Fabien)
Date: Wed, 4 Nov 2015 09:39:09 +0100
Subject: Is it ok to install python binaries on a network drive?
References: <n0qe0v$qdu$1@speranza.aioe.org>
 <56320bf9$0$1587$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1cg7c$cv0$1@speranza.aioe.org>

On 10/29/2015 01:07 PM, Steven D'Aprano wrote:
>> My question is: what will happen when about 20 students will do the same
>> >at the same time? I know too little about what's going under the hood
>> >with an "import X" command to be able to predict problems that might
>> >occur.
> I think it should be fine.

Dear all,

I just wanted to report that everything worked fine. It wasn't even too 
slow. I find it a quite elegant solution after all for all the students 
to have the same working environment.

Thanks!

Fabien


From steve+comp.lang.python at pearwood.info  Wed Nov  4 03:47:58 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 19:47:58 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com> <n1cbi4$ao5$1@dont-email.me>
Message-ID: <5639c63f$0$2897$c3e8da3$76491128@news.astraweb.com>

On Wednesday 04 November 2015 18:21, Christian Gollwitzer wrote:

> What rurpy meant, was that regexes can surface to a computer user
> earlier than variables and branches; a user who does not go into the
> depth to actually program the machine, might still encounter them in a
> text editor or database engine. Even some web forms allow some limited
> form, like e.g. the DVD rental here or Google.

What Rurpy meant, only Rurpy can say, but I doubt that is what he is talking 
about. By that logic, a full-screen high-def 3D first-person shooter game 
with an advanced AI is "more fundamental" than an assembly language branch 
operation, because there are people who play computer games without doing 
assembly programming.

In context, Michael suggested that programmers should learn the basic 
fundamentals of their chosen language, such as variables, for-loops and 
branching, before regexes -- which Rurpy then disagreed with, claiming that 
regexes are more fundamental than those basic operations.

What *I* think that Rurpy means is that one can construct a mathematical 
system based on pattern matching which is Turing complete, and therefore in 
principle any problem you can solve using a program written in (say) Python, 
C, Lisp, Smalltalk, etc, or execute on a CPU (or simulate in your head!) 
could be written as a sufficiently complex regular expression.

I think he is *technically wrong*, if by "regex" we mean actual regular 
expressions. Perl, and Python, regexes are strictly more powerful than 
regular expressions (despite the name). I know that Perl regexes are Turing 
complete (mainly because they can call out to the Perl interpreter), I'm not 
sure about Python regexes.

But I also think that Rurpy is *not even wrong* if he means Perl or Python 
regexes. The (entirely theoretical) ability to solve a problem like "What is 
pi to the power of the first prime number larger than 97531000?" using a 
regex doesn't make regexes more fundamental than variables, branches and 
loops. It just makes them an alternative computing paradigm -- one which is 
*exponentially* more difficult to use than the standard paradigms of 
functional, procedural, OOP, etc. for anything except the limited subset of 
pattern matching problems they were created for.



-- 
Steve



From __peter__ at web.de  Wed Nov  4 03:57:02 2015
From: __peter__ at web.de (Peter Otten)
Date: Wed, 04 Nov 2015 09:57:02 +0100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
Message-ID: <n1ch8v$irh$1@ger.gmane.org>

Michael Torrie wrote:

> On 11/03/2015 08:23 PM, Steven D'Aprano wrote:
>>>> Grep can use regular expressions (and I do so with it regularly), but
>>>> it's default mode is certainly not regular expressions ...
>>>
>>> Its very name indicates that its default mode most certainly is regular
>>> expressions.
>> 
>> I don't even know what grep stands for.
>> 
>> But I think what Michael may mean is that if you "grep foo", no regex
>> magic takes place since "foo" contains no metacharacters.
> 
> More likely I just don't know what I'm talking about.  I must have been
> thinking about something else (shell globbing perhaps).
> 
> Certainly most of the times I've seen grep used, it's to look for a word
> with no special metacharacters, as you say. Still a valid RE of course.
>  But I have learned to night I don't need to resort to grep -e to use
> regular expressions.  At least with GNU grep, that's the default.

Well, I didn't know that grep uses regular expressions by default.

I tried Tim's example

$ seq 5 | grep '1*'
1
2
3
4
5
$ 

which surprised me because I remembered that there usually weren't any 
matching lines when I invoked grep instead of egrep by mistake. So I tried 
another one

$ seq 5 | grep '[1-3]+'
$ 

and then headed for the man page. Apparently there is a subset called "basic 
regular expressions":

"""
  Basic vs Extended Regular Expressions
       In basic regular expressions the meta-characters ?, +, {, |, (,
       and ) lose their special meaning; instead use  the  backslashed
       versions \?, \+, \{, \|, \(, and \).
"""




From oscar.j.benjamin at gmail.com  Wed Nov  4 05:07:14 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 4 Nov 2015 10:07:14 +0000
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <56397dd9$0$1601$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <mailman.37.1446569907.8789.python-list@python.org>
 <56397dd9$0$1601$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAHVvXxQtAWv0hUvOush9en_frh2W4fagYL3Uh_i2osDnYqxsQw@mail.gmail.com>

On 4 November 2015 at 03:39, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>
> Better would be this:
>
> def chomp(lines):
>     for line in lines:
>         yield line.rstrip()  # remove all trailing whitespace
>
>
> with open(...) as f:
>     for line in chomp(f): ...

with open(...) as f:
    for line in map(str.rstrip, f): ...

--
Oscar


From mail at timgolden.me.uk  Wed Nov  4 05:08:41 2015
From: mail at timgolden.me.uk (Tim Golden)
Date: Wed, 4 Nov 2015 10:08:41 +0000
Subject: Creating PST files using Python
In-Reply-To: <CAPTjJmrVrLYrFvHuMR1Sjv59D_8UAA_wovKBRXfEdnU3oTPCPQ@mail.gmail.com>
References: <873907D8-7E21-4F08-AF07-A83F766802BA@cajuntechie.org>
 <CAPTjJmrVrLYrFvHuMR1Sjv59D_8UAA_wovKBRXfEdnU3oTPCPQ@mail.gmail.com>
Message-ID: <5639D929.3050506@timgolden.me.uk>

On 03/11/2015 22:12, Chris Angelico wrote:
> On Wed, Nov 4, 2015 at 6:09 AM, Anthony Papillion 
> <anthony at cajuntechie.org> wrote:
>> Does anyone know of a module that allows the wiring of Outlook PST
>> files using Python? I'm working on a project that will require me
>> to migrate 60gb of maildir mail (multiple accounts) to Outlook.

I don't know if this is quite what you were after but, if automating
Outlook is an option (ie using its COM object model), the code below is
an *extremely* Q&D approach to adding a PST and copying the messages in
a mbox one by one.

Obviously I've done just enough to show that it's viable, and none of
the more complicated work around conversation ids, multipart messages etc.

TJG

#!python3
import os, sys
import gzip
import mailbox
import urllib.request

import win32com.client
dispatch = win32com.client.gencache.EnsureDispatch
const = win32com.client.constants

PST_FILEPATH =
os.path.abspath(os.path.join(os.path.expandvars("%APPDATA%"),
"scratch.pst"))
if os.path.exists(PST_FILEPATH):
    os.remove(PST_FILEPATH)
ARCHIVE_URL =
"https://mail.python.org/pipermail/python-list/2015-November.txt.gz"
MBOX_FILEPATH = "archive.mbox"

def download_archive(url, local_mbox):
    with gzip.open(urllib.request.urlopen(url)) as archive:
        with open(local_mbox, "wb") as f:
            print("Writing %s to %s" % (url, local_mbox))
            f.write(archive.read())

def copy_archive_to_pst(mbox_filepath, pst_folder):
    archive = mailbox.mbox(mbox_filepath)
    for message in archive:
        print(message.get("Subject"))
        pst_message = pst_folder.Items.Add()
        pst_message.Subject = message.get("Subject")
        pst_message.Sender = message.get("From")
        pst_message.Body = message.get_payload()
        pst_message.Move(pst_folder)
        pst_message.Save()

def find_pst_folder(namespace, pst_filepath):
    for store in dispatch(mapi.Stores):
        if store.IsDataFileStore and store.FilePath == PST_FILEPATH:
            return store.GetRootFolder()

download_archive(ARCHIVE_URL, MBOX_FILEPATH)
outlook = dispatch("Outlook.Application")
mapi = outlook.GetNamespace("MAPI")
pst_folder = find_pst_folder(mapi, PST_FILEPATH)
if not pst_folder:
    mapi.AddStoreEx(PST_FILEPATH, const.olStoreDefault)
    pst_folder = find_pst_folder(mapi, PST_FILEPATH)
if not pst_folder:
    raise RuntimeError("Can't find PST folder at %s" % PST_FILEPATH)
copy_archive_to_pst(MBOX_FILEPATH, pst_folder)


From steve at pearwood.info  Wed Nov  4 05:24:29 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 04 Nov 2015 21:24:29 +1100
Subject: Unbuffered stderr in Python 3
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
 <mailman.5.1446625197.16136.python-list@python.org>
Message-ID: <5639dcdf$0$1620$c3e8da3$5496439d@news.astraweb.com>

On Wed, 4 Nov 2015 07:19 pm, Wolfgang Maier wrote:

> On 04.11.2015 04:18, Steven D'Aprano wrote:
>> On Wednesday 04 November 2015 09:25, Terry Reedy wrote:
>>
>>> On 11/3/2015 10:42 AM, Chris Angelico wrote:
>>>> On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com>
>>>> wrote:
>>>>> Nobody <nobody at nowhere.invalid> writes:
>>>>>
>>>>>> It's probably related to the fact that std{in,out,err} are Unicode
>>>>>> streams.
>>>>>
>>>>> There's no fundamental reason a Unicode stream should have to be line
>>>>> buffered. If it's "related", it's only in that an oversight was made
>>>>> in the course of making that change.
>>>
>>> The current behavior is not an 'oversight'.  I was considered, decided,
>>> and revisited in https://bugs.python.org/issue13601.  Guido:
>>> "Line-buffering should be good enough since in practice errors messages
>>> are always terminated by a newline."  If not, print(part_line,
>>> file=sys.stderr, flush=True) works for the unusual case.
>>
>> This is one of the offending line from our code base:
>>
>> print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)
>>
>> So that ought to be terminated by a newline. And yet, the stderr output
>> doesn't show up until the program exits.
>>
> 
> For me, that prints immediately. Where is your output going? Console,
> file, ...?

Going to stderr, like the whole thread is about :-)


The output does eventually show up written to the console, but only after
Python exits.



-- 
Steven



From wolfgang.maier at biologie.uni-freiburg.de  Wed Nov  4 05:43:18 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Wed, 4 Nov 2015 11:43:18 +0100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <5639dcdf$0$1620$c3e8da3$5496439d@news.astraweb.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
 <mailman.5.1446625197.16136.python-list@python.org>
 <5639dcdf$0$1620$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1cng6$m9a$1@ger.gmane.org>

On 04.11.2015 11:24, Steven D'Aprano wrote:
> On Wed, 4 Nov 2015 07:19 pm, Wolfgang Maier wrote:
>
>> On 04.11.2015 04:18, Steven D'Aprano wrote:
>>>
>>> This is one of the offending line from our code base:
>>>
>>> print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)
>>>
>>> So that ought to be terminated by a newline. And yet, the stderr output
>>> doesn't show up until the program exits.
>>>
>>
>> For me, that prints immediately. Where is your output going? Console,
>> file, ...?
>
> Going to stderr, like the whole thread is about :-)
>

I see :), but seriously, what I meant was: is it going to the console 
directly or is your code base redirecting sys.stderr to another buffered 
object first?

>
> The output does eventually show up written to the console, but only after
> Python exits.
>
>
>



From antoon.pardon at rece.vub.ac.be  Wed Nov  4 06:41:23 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 04 Nov 2015 12:41:23 +0100
Subject: Regular expressions
In-Reply-To: <56397cfd$0$1601$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.28.1446564855.8789.python-list@python.org>
 <tjmh3blsb60fmvginp4q6sbe2659p4rh9f@4ax.com>
 <mailman.34.1446567607.8789.python-list@python.org>
 <56397cfd$0$1601$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5639EEE3.10703@rece.vub.ac.be>

Op 04-11-15 om 04:35 schreef Steven D'Aprano:
> On Wednesday 04 November 2015 03:20, Chris Angelico wrote:
>
>> (So,
>> too, are all the comments about using [-1] or string methods. But we
>> weren't to know that.)
> If MRAB could understand what he wanted, I'm sure most others could have 
> too.

Yes, they were just to busy to try pushing the OP in an other direction, for
them to answer the question.

-- 
Antoon Pardon



From wolfgang.maier at biologie.uni-freiburg.de  Wed Nov  4 06:49:49 2015
From: wolfgang.maier at biologie.uni-freiburg.de (Wolfgang Maier)
Date: Wed, 4 Nov 2015 12:49:49 +0100
Subject: Unbuffered stderr in Python 3
In-Reply-To: <n1cng6$m9a$1@ger.gmane.org>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
 <mailman.5.1446625197.16136.python-list@python.org>
 <5639dcdf$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <n1cng6$m9a$1@ger.gmane.org>
Message-ID: <n1crct$jgv$1@ger.gmane.org>

On 04.11.2015 11:43, Wolfgang Maier wrote:
> On 04.11.2015 11:24, Steven D'Aprano wrote:
>> On Wed, 4 Nov 2015 07:19 pm, Wolfgang Maier wrote:
>>
>>> On 04.11.2015 04:18, Steven D'Aprano wrote:
>>>>
>>>> This is one of the offending line from our code base:
>>>>
>>>> print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)
>>>>
>>>> So that ought to be terminated by a newline. And yet, the stderr output
>>>> doesn't show up until the program exits.
>>>>
>>>
>>> For me, that prints immediately. Where is your output going? Console,
>>> file, ...?
>>
>> Going to stderr, like the whole thread is about :-)
>>
>
> I see :), but seriously, what I meant was: is it going to the console
> directly or is your code base redirecting sys.stderr to another buffered
> object first?
>

Standard I/O streams are line-buffered only if interactive (i.e., 
connected to a console), but block-buffered otherwise.
What does sys.stderr.isatty() return?




From c.zallmann at web.de  Wed Nov  4 07:41:00 2015
From: c.zallmann at web.de (Christoph Zallmann)
Date: Wed, 4 Nov 2015 13:41:00 +0100
Subject: pycrypto
Message-ID: <003501d116fe$0f502570$2df07050$@web.de>

Hey there,

 

i tried using Python 3.5.0 in combination with pycrypto and everything i got
was crap. Really. I tried so many things, how to solve my problem - using
environment variables, vs 2015 and many more. With python 2.7 or even 3.4 i
heard it was no problem but using 3.5 all i got was one error message that
leads to the next error message. Can you tell me how to install python 3.5
on Windows 10 with a working pycrpto on it? As well pip as easy_install
threw the same errors e.g. "No matching distribution found for pycrypto" or 

error: Setup script exyited with error: Unable to find vcvarsall.bat 

 

Can u give me a suited solution that simply works for me?

 

Thanks and greetings,

Chris



From invalid at invalid.invalid  Wed Nov  4 08:27:45 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 4 Nov 2015 13:27:45 +0000 (UTC)
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.3.1446608844.16136.python-list@python.org>
Message-ID: <n1d14h$hii$2@reader1.panix.com>

On 2015-11-04, Michael Torrie <torriem at gmail.com> wrote:
> On 11/03/2015 08:23 PM, Steven D'Aprano wrote:
>>
>>>> Grep can use regular expressions (and I do so with it regularly), but
>>>> it's default mode is certainly not regular expressions ...
>>>
>>> Its very name indicates that its default mode most certainly is
>>> regular expressions.
>> 
>> I don't even know what grep stands for. 

General Regular Expression Parser (or somesuch)

>> But I think what Michael may mean is that if you "grep foo", no regex
>> magic takes place since "foo" contains no metacharacters.
>
> More likely I just don't know what I'm talking about.  I must have
> been thinking about something else (shell globbing perhaps).
>
> Certainly most of the times I've seen grep used, it's to look for a
> word with no special metacharacters, as you say. Still a valid RE of
> course. But I have learned to night I don't need to resort to grep -e
> to use regular expressions.

The -e turns on "enhanced" regexes which add a few more features to
the regex language it parses.  I've never been entirely sure if the -e
regex language is backwards compatible with the default one or not...

> At least with GNU grep, that's the default.

Grep has always by default parsed its first command line argument (at
least since v7 and Sys5).  If you didn't want it treated as a regex,
you had to specify -f.

-- 
Grant Edwards               grant.b.edwards        Yow! I like your SNOOPY
                                  at               POSTER!!
                              gmail.com            


From random832 at fastmail.com  Wed Nov  4 08:43:56 2015
From: random832 at fastmail.com (Random832)
Date: Wed, 04 Nov 2015 08:43:56 -0500
Subject: Unbuffered stderr in Python 3
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
 <mailman.5.1446625197.16136.python-list@python.org>
 <5639dcdf$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <n1cng6$m9a$1@ger.gmane.org> <n1crct$jgv$1@ger.gmane.org>
Message-ID: <87twp1op5v.fsf@fastmail.com>

Wolfgang Maier <wolfgang.maier at biologie.uni-freiburg.de> writes:
> Standard I/O streams are line-buffered only if interactive (i.e.,
> connected to a console), but block-buffered otherwise.

That's not appropriate for stderr, nor is it justified by the argument
that Terry Reedy cited earlier. I had assumed he was making an implicit
claim that stderr is _always_ line-buffered, _even if_ it is not
interactive.

> What does sys.stderr.isatty() return?

There are many situations in which a nominally interactive process might
not have a "tty" for stderr on MS Windows. In an Emacs M-x shell buffer,
in a cygwin terminal (for a non-cygwin python), etc.



From rurpy at yahoo.com  Wed Nov  4 09:38:19 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 06:38:19 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <56398006$0$11100$c3e8da3@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
Message-ID: <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>

On 11/03/2015 08:48 PM, Steven D'Aprano wrote:
> On Wednesday 04 November 2015 11:33, rurpy wrote:
>
>>> Not quite.  Core language concepts like ifs, loops, functions,
>>> variables, slicing, etc are the socket wrenches of the programmer's
>>> toolbox.  Regexs are like an electric impact socket wrench.  You can do
>>> the same work without it, but in many cases it's slower. But you have to
>>> learn the other hand tools first in order to really use the electric
>>> driver properly (understanding torques, direction of threads, etc), lest
>>> you wonder why you're breaking off so many bolts with the torque of the
>>> impact drive.
>>
>> I consider regexs more fundemental
>
> I'm sure that there are people who consider the International Space Station 
> more fundamental than the lever, the wedge and the hammer, but they would be 
> wrong too.
>
> Given primitives for branching, loops and variables, you can build support 
> for regexes. Given regexes, how would you build support for variables?
>
> Of course, you could easily prove me wrong. All you would need to do to 
> demonstrate that regexes are more fundamental than branching, loops and 
> variables would be to demonstrate that the primitive operations available in 
> commonly used CPUs are regular expressions, and that (for example) C's for 
> loop and if...else are implemented in machine code as regular expressions, 
> rather than the other way around.

I'm afraid you are making a category error but perhaps that's in 
part because I wasn't clear.  I was not talking about computer 
science.  I was talking about human beings learning about computers.  
Most people I know consider programming to be a higher level activity 
than "using" a computer: editing, sending email etc.  Many computer
users (not programmers) learn to use regular expressions as part
of using a computer without knowing anything about programming.
It was on that basis I called them more fundamental -- something
learned earlier which is expanded on and added to later.  But you
have a bit of a point, perhaps "fundamental" was not the best choice
of word to communicate that.

Here is what I wrote:

> I consider regexs more fundemental.  One need not even be a programmer
> to use them: consider grep, sed, a zillion editors, database query 
> languages, etc.

I thought the context, which you removed even to the point cutting 
text from the very same line you quoted, made that clear but perhaps
not.

Indeed it is quite eye-opening when one does learn a little CS and 
discovers these things that were just a useful "feature" actually have 
a deep and profound theoretical basis.


From rurpy at yahoo.com  Wed Nov  4 09:43:19 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 06:43:19 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <5639c63f$0$2897$c3e8da3$76491128@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <n1cbi4$ao5$1@dont-email.me>
 <5639c63f$0$2897$c3e8da3$76491128@news.astraweb.com>
Message-ID: <f0ae8c1e-5217-495f-842f-b5c6d86a3e8a@googlegroups.com>

On Wednesday, November 4, 2015 at 1:52:31 AM UTC-7, Steven D'Aprano wrote:
> On Wednesday 04 November 2015 18:21, Christian Gollwitzer wrote:
> 
> > What rurpy meant, was that regexes can surface to a computer user
> > earlier than variables and branches; a user who does not go into the
> > depth to actually program the machine, might still encounter them in a
> > text editor or database engine. Even some web forms allow some limited
> > form, like e.g. the DVD rental here or Google.
> [...]
> What *I* think that Rurpy means is that one can construct a mathematical 
> system based on pattern matching which is Turing complete, and therefore in 
> principle any problem you can solve using a program written in (say) Python, 
> C, Lisp, Smalltalk, etc, or execute on a CPU (or simulate in your head!) 
> could be written as a sufficiently complex regular expression.

No, Christian was correct.


From rosuav at gmail.com  Wed Nov  4 09:52:08 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 01:52:08 +1100
Subject: Regular expressions
In-Reply-To: <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
Message-ID: <CAPTjJmrPvA4ENxPmu+YPCkymh_OAw=vHkBLGgXuRggJorzJeNg@mail.gmail.com>

On Thu, Nov 5, 2015 at 1:38 AM, rurpy--- via Python-list
<python-list at python.org> wrote:
> I'm afraid you are making a category error but perhaps that's in
> part because I wasn't clear.  I was not talking about computer
> science.  I was talking about human beings learning about computers.
> Most people I know consider programming to be a higher level activity
> than "using" a computer: editing, sending email etc.  Many computer
> users (not programmers) learn to use regular expressions as part
> of using a computer without knowing anything about programming.
> It was on that basis I called them more fundamental -- something
> learned earlier which is expanded on and added to later.  But you
> have a bit of a point, perhaps "fundamental" was not the best choice
> of word to communicate that.

The "fundamentals" of something are its most basic functions, not its
most basic uses. The most common use of a computer might be to browse
the web, but the fundamental functionality is arithmetic and logic.

Setting aside the choice of word, though, I still don't think regular
expressions are a more basic use of computing than loops and
conditionals. A regex can't be used for anything other than string
matching; they exist for one purpose, and one purpose only: to answer
the question "Does this string match this pattern?". Sure, you can
abuse that into a primality check and other forms of crazy arithmetic,
but it's not what they truly do. I also would not teach regexes to
people as part of an "introduction to computing" course, any more than
I would teach the use of Microsoft Excel, which some such courses have
been known to do. (And no, it's not because of the Microsoftness. I
wouldn't teach LibreOffice Calc either.) You don't need to know how to
work a spreadsheet as part of the basics of computer usage, and you
definitely don't need an advanced form of text search.

ChrisA


From torriem at gmail.com  Wed Nov  4 10:13:51 2015
From: torriem at gmail.com (Michael Torrie)
Date: Wed, 04 Nov 2015 08:13:51 -0700
Subject: Regular expressions
In-Reply-To: <n1ch8v$irh$1@ger.gmane.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
Message-ID: <563A20AF.1070002@gmail.com>

On 11/04/2015 01:57 AM, Peter Otten wrote:
> and then headed for the man page. Apparently there is a subset
> called "basic regular expressions":
>
> """>   Basic vs Extended Regular Expressions
>        In basic regular expressions the meta-characters ?, +, {, |, (,
>        and ) lose their special meaning; instead use  the  backslashed
>        versions \?, \+, \{, \|, \(, and \).
> """

Good catch. I think this must have been what my brain was thinking when
I commented about grep and regular expressions earlier. I checked the
man page but didn't read down far enough.

I was still technically wrong though.

It's neat to learn so much on these tangents that the python list goes
on frequently. Hope the OP is still lurking, reading all these comments,
though I suspect he's not.




From python.list at tim.thechases.com  Wed Nov  4 10:33:02 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 4 Nov 2015 09:33:02 -0600
Subject: Irregular last line in a text file, was Re: Regular expressions
In-Reply-To: <56397dd9$0$1601$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <20151102204237.6a78abdf@bigbox.christie.dr>
 <56382F33.8050905@gmail.com> <n19ui8$df7$1@ger.gmane.org>
 <20151103055018.535e3e42@bigbox.christie.dr>
 <mailman.21.1446559261.8789.python-list@python.org>
 <lf5io5junfn.fsf@ling.helsinki.fi> <n1ak7u$jgs$1@ger.gmane.org>
 <mailman.37.1446569907.8789.python-list@python.org>
 <56397dd9$0$1601$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <20151104093302.12186ee1@bigbox.christie.dr>

On 2015-11-04 14:39, Steven D'Aprano wrote:
> On Wednesday 04 November 2015 03:56, Tim Chase wrote:
>> Or even more valuable to me:
>> 
>>   with open(..., newline="strip") as f:
>>     assert all(not line.endswith(("\n", "\r")) for line in f)
> 
> # Works only on Windows text files.
> def chomp(lines):
>     for line in lines:
>         yield line.rstrip('\r\n')

.rstrip() takes a string that is a set of characters, so it will
remove any \r or \n at the end of the string (so it works with
both Windows & *nix line-endings) whereas just using .rstrip()
without a parameter can throw away data you might want:

  >>> "hello \r\n\r\r\n\n\n".rstrip("\r\n")
  'hello '
  >>> "hello \r\n\r\r\n\n\n".rstrip()
  'hello'

-tkc






From python.list at tim.thechases.com  Wed Nov  4 10:42:16 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 4 Nov 2015 09:42:16 -0600
Subject: Regular expressions
In-Reply-To: <n1ch8v$irh$1@ger.gmane.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
Message-ID: <20151104094216.3f7e3006@bigbox.christie.dr>

On 2015-11-04 09:57, Peter Otten wrote:
> Well, I didn't know that grep uses regular expressions by default.

It doesn't help that grep(1) comes in multiple flavors:

grep:  should use BRE (Basic REs)
fgrep:  same as "grep -F"; uses fixed strings, no REs
egrep:  same as "grep -E"; uses ERE (Extended REs)
grep -P: a GNUism to use PCREs (Perl Compatible REs)

there's also an "rgrep" which is just "grep -r" which I find kinda
silly/redundant. Though frankly I feel the same way about fgrep/egrep
since they just activate a command-line switch.

You get even crazier when you start adding zgrep/zegrep/zfgrep.

-tkc




From df at see.replyto.invalid  Wed Nov  4 10:55:12 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Wed, 04 Nov 2015 15:55:12 +0000
Subject: Unbuffered stderr in Python 3
References: <mailman.30.1446570002.25765.python-list@python.org>
 <5638F707.90309@noaa.gov> <mailman.47.1446579961.8789.python-list@python.org>
Message-ID: <h2ak3bh20v5kft7u87q6139ehircqp43vp@4ax.com>

Random832 <random832 at fastmail.com> wrote:

>The opposite of line buffering is not no buffering, but full
>(i.e. block) buffering, that doesn't get flushed until it runs
>out of space. TextIOWrapper has its own internal buffer, and its
>design apparently doesn't contemplate the possibility of using
>it with a raw FileIO object (which may mean that the posted code
>isn't guaranteed to work) or disabling buffering.

Hmmm. That even seems to cause trouble for sys.stderr.write
(in Python3 with a non-tty e.g. a piped output):

$ python2 -c 'import sys;sys.stderr.write("1\n");print("2")' 2>&1 | tee
1
2
$ python3 -c 'import sys;sys.stderr.write("1\n");print("2")' 2>&1 | tee
2
1


From ian.g.kelly at gmail.com  Wed Nov  4 10:56:56 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 4 Nov 2015 08:56:56 -0700
Subject: pycrypto
In-Reply-To: <003501d116fe$0f502570$2df07050$@web.de>
References: <003501d116fe$0f502570$2df07050$@web.de>
Message-ID: <CALwzid=29_jbtB2hmi1JCmCfBUB_qdemU=PA5nhV8gGtKOn4hA@mail.gmail.com>

On Wed, Nov 4, 2015 at 5:41 AM, Christoph Zallmann <c.zallmann at web.de> wrote:
> Hey there,
>
>
>
> i tried using Python 3.5.0 in combination with pycrypto and everything i got
> was crap. Really. I tried so many things, how to solve my problem - using
> environment variables, vs 2015 and many more. With python 2.7 or even 3.4 i
> heard it was no problem but using 3.5 all i got was one error message that
> leads to the next error message. Can you tell me how to install python 3.5
> on Windows 10 with a working pycrpto on it? As well pip as easy_install
> threw the same errors e.g. "No matching distribution found for pycrypto" or
>
> error: Setup script exyited with error: Unable to find vcvarsall.bat
>
>
>
> Can u give me a suited solution that simply works for me?

http://stackoverflow.com/questions/11405549/how-do-i-install-pycrypto-on-windows


From geneva.storey at fultonind.kyschools.us  Wed Nov  4 13:18:30 2015
From: geneva.storey at fultonind.kyschools.us (Storey, Geneva)
Date: Wed, 4 Nov 2015 18:18:30 +0000
Subject: teacher need help!
In-Reply-To: <BLUPR0201MB1524BEDFAD098F598BE43F1ED6390@BLUPR0201MB1524.namprd02.prod.outlook.com>
References: <BLUPR0201MB1524EDBB3F8C367250412FEFD63C0@BLUPR0201MB1524.namprd02.prod.outlook.com>
 <5623397C.40205@timgolden.me.uk>
 <CANy1k1iq-9K_D+iVUW4ErFF5QvByH3r+WMVyHdq2Mrr9nbeNhg@mail.gmail.com>
 <BLUPR0201MB1524A5C40F14DD282BA0A379D63A0@BLUPR0201MB1524.namprd02.prod.outlook.com>,
 <5624AC43.3080105@timgolden.me.uk>,
 <BLUPR0201MB1524BEDFAD098F598BE43F1ED6390@BLUPR0201MB1524.namprd02.prod.outlook.com>
Message-ID: <BLUPR0201MB1524FF0A22E3FD0E8A6439E7D62A0@BLUPR0201MB1524.namprd02.prod.outlook.com>





I am having the same problem that we experienced earlier (see below).  This student was exploring random numbers in Python.  She named her program random which caused confusion for her computer.  We deleted the file, but still had the problem.  I removed Python from the machine.  When I tried to reinstall, I got the attached error message.  Now it won't even install.  Any suggestions would be greatly appreciated!
Thanks,
Geneva



Geneva Storey

Fulton High School

Spanish, Mathematics

Bulldog Academy

________________________________________
From: Storey, Geneva
Sent: Tuesday, October 20, 2015 11:25 AM
To: Tim Golden
Cc: python-list at python.org
Subject: Re: teacher need help!

FYI-We formatted the machines, reinstalling everything, including Python.  I works with no problems now.  Confusing that this would happen on 3 out of 13 machines.  Just letting you know, all is well.  Thank you for your help!
Geneva

Geneva Storey

Fulton High School

Spanish, Mathematics

Bulldog Academy

________________________________________
From: Tim Golden <mail at timgolden.me.uk>
Sent: Monday, October 19, 2015 3:39 AM
To: Storey, Geneva
Cc: python-list at python.org
Subject: Re: teacher need help!

On 19/10/2015 02:32, Storey, Geneva wrote:
> Same issue!  See attached.
> Thanks!

Geneva -- please try to post text, not pictures. Just use the mouse to
cut-and-paste the entirety of the text from that window into an email.
Otherwise some of the people who are trying to help you can't actually
see what the problem is!

[
Traceback show the same error coming from:
c:\windows\system32\turtle.py
]

This is a bit more tricky than it appears. If you're running on 64-bit
Windows (which I can't tell from your screenshot) but your Python
installation is 32-bit (which it is) then the folder which Python sees
as "c:\windows\system32" is not the same folder which the normal Windows
Explorer sees as "c:\windows\system32".

Can you try going to this folder in Explorer:

C:\windows\SysWOW64

and see if there's a turtle.py file there? If there is, move or delete
it and try again.

If that still doesn't work, can you tell us which version of Windows
you're running, and whether it's 32 or 64-bit, please? If you're not
sure how to get that information, try following the instructions here:

http://ramblings.timgolden.me.uk/2015/10/08/what-windows-version-am-i-running/

TJG


From ben+python at benfinney.id.au  Wed Nov  4 13:24:03 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 05 Nov 2015 05:24:03 +1100
Subject: What does =?utf-8?B?4oCcZ3JlcOKAnQ==?= stand for? (was: Regular
 expressions)
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <85wptxk4ho.fsf_-_@benfinney.id.au>

Steven D'Aprano <steve+comp.lang.python at pearwood.info> writes:

> On Wednesday 04 November 2015 13:55, Dan Sommers wrote:
>
> > Its very name indicates that its default mode most certainly is
> > regular expressions.
>
> I don't even know what grep stands for. 

?grep? stands for ?g/RE/p?.

The name is a mnemonic for a compound command in ?ed? [0], a text editor
that pre-dates extravagant luxuries like ?presenting a full screen of
text at one time?.


In an ?ed? session, the user is obliged to keep mental track of the
current line in the text buffer, and even what that text contains during
the session.

Single-letter commands, with various terse parameters such as the range
of lines or some text to insert, are issued at a command prompt one
after another.

For these reasons, the manual page describes ?ed? as a ?line-oriented
text editor?. Everything is done by specifying lines, blindly, to
commands which then operate on those lines.

The name of the ?vi? editor means ?visual interface (to a text editor)?,
to proudly declare the innovation of a full screen of text that updates
content during the editing session. That was not available for users of
?ed?.


A very common command to issue, then, is ?actually show me the line of
text I just specified?; the ?p? (for ?print?) command.

Another very common command is ?find the text matching this pattern and
perform these commands on it?, which is ?g? (for ?global?). The ?g?
command addresses text matching a regular expression pattern, delimited
by slashes ?/?.

So, for users with feeble human brains incapable of remembering
perfectly the entire content of the text while it changes and therefore
not always knowing exactly which lines they wanted to operate on without
seeing them all the time, a very frequent combination command is:

    g/RE/p

meaning ?find lines forward from here that match the regular expression
pattern ?RE?, and do nothing to those lines except print them to
standard output?.


Wikipedia has useful pages on both ?grep? and ?ed?
<URL:https://en.wikipedia.org/wiki/Grep>
<URL:https://en.wikipedia.org/wiki/Ed_%28text_editor%29>.

You can see a full specification of how the ?ed? interface is to behave
as part of the ?Open Group Base Specifications Issue 7?, which is the
specification for Unix.

    <URL:http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ed.html>

See the manual for GNU ed which includes an example session to
appreciate just how far things have come.

    <URL:https://www.gnu.org/software/ed/manual/ed_manual.html#Introduction-to-line-editing>

Of course, if you yearn for the days of minimalist purity, nothing beats
Ed, man! !man ed


[0] The standard text editor.
    <URL:https://www.gnu.org/fun/jokes/ed-msg.txt>

-- 
 \     ?If you can't annoy somebody there is little point in writing.? |
  `\                                                    ?Kingsley Amis |
_o__)                                                                  |
Ben Finney



From gandalf at shopzeus.com  Wed Nov  4 13:31:37 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Wed, 4 Nov 2015 19:31:37 +0100
Subject: pycrypto
In-Reply-To: <CALwzid=29_jbtB2hmi1JCmCfBUB_qdemU=PA5nhV8gGtKOn4hA@mail.gmail.com>
References: <003501d116fe$0f502570$2df07050$@web.de>
 <CALwzid=29_jbtB2hmi1JCmCfBUB_qdemU=PA5nhV8gGtKOn4hA@mail.gmail.com>
Message-ID: <563A4F09.2030206@shopzeus.com>




Can u give me a suited solution that simply works for me?

> http://stackoverflow.com/questions/11405549/how-do-i-install-pycrypto-on-windows
Voidspace only has Python 3.3. They are usually behind some minor
versions. The only good way to do this is to compile it from sources.
Unfortunately, not everbody has an MSVC license...

I find it **very** annoying that every time I need to download binary
PyCrypto for the latest CPython, I have to search for it on the net.
Sometimes it cannot be found for a week. :-(

For the OP's question, here is the relevant stackoverflow question:

http://stackoverflow.com/questions/32800336/pycrypto-on-python-3-5

And here are some compiled versions that can be downloaded and installed
with PIP:

https://github.com/sfbahr/PyCrypto-Wheels

Why don't we have binary packages for PyCrypto, uploaded to PyPi? It
seems that there are persons who can compile it, but there are no
official packagers. I would happily do it for others, but I don't have
an MSVC license. :-(





From python.list at tim.thechases.com  Wed Nov  4 14:05:48 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 4 Nov 2015 13:05:48 -0600
Subject: What does =?UTF-8?B?4oCcZ3JlcOKAnQ==?= stand for? (was: Regular
 expressions)
In-Reply-To: <85wptxk4ho.fsf_-_@benfinney.id.au>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <85wptxk4ho.fsf_-_@benfinney.id.au>
Message-ID: <20151104130548.0b6a2947@bigbox.christie.dr>

On 2015-11-05 05:24, Ben Finney wrote:
> A very common command to issue, then, is ?actually show me the line
> of text I just specified?; the ?p? (for ?print?) command.
> 
> Another very common command is ?find the text matching this pattern
> and perform these commands on it?, which is ?g? (for ?global?). The
> ?g? command addresses text matching a regular expression pattern,
> delimited by slashes ?/?.
> 
> So, for users with feeble human brains incapable of remembering
> perfectly the entire content of the text while it changes and
> therefore not always knowing exactly which lines they wanted to
> operate on without seeing them all the time, a very frequent
> combination command is:
> 
>     g/RE/p

Though since the default action for g/ is to print the line, I've
always wondered why the utility wasn't named just "gre"

   $ ed myfile.txt
   g/re
   [matching lines follow]
   q
   $

-tkc
(the goofball behind https://twitter.com/ed1conf )






From femtv123 at gmail.com  Wed Nov  4 14:38:00 2015
From: femtv123 at gmail.com (alperen)
Date: Wed, 4 Nov 2015 11:38:00 -0800 (PST)
Subject: any practise site about python?
Message-ID: <4b7392fb-8639-49d2-a09d-a06bbbcbcff7@googlegroups.com>

hi guys.
i am computer engineering student and i want to practise the lectures that i saw at school. for example dictionaries tuples or some other topics. i know eulerproject but it is hard for starting. do you know any exercise sites for students or beginners


From auriocus at gmx.de  Wed Nov  4 14:38:21 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 4 Nov 2015 20:38:21 +0100
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <mailman.23.1446661467.16136.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
Message-ID: <n1dmn7$fnq$1@dont-email.me>

Am 04.11.15 um 19:24 schrieb Ben Finney:
> The name is a mnemonic for a compound command in ?ed? [0], a text editor
> that pre-dates extravagant luxuries like ?presenting a full screen of
> text at one time?.
>
>  [... lots of fun facts ...]

Here is another fun fact: The convincing UI of ed was actually so widely 
applied, that even Microsoft included a similar editor into MSDOS, 
called EDLIN. EDLIN, of course, was a bastardized version of ed that 
could do much less and also lacked regular expressions. Needless to say 
that the mighty "VIsual" editor was out 5 years before MSDOS shipped 
EDLIN as the only editor...

In contrast to ed, the stream editor "sed" is used multiple times avery 
day in a typical Unix session inside shell scripts to perform automated 
text processing tasks, including regex replacement.

	Christian


From israel at ravnalaska.net  Wed Nov  4 15:13:00 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Wed, 4 Nov 2015 11:13:00 -0900
Subject: CherryPy cpstats and ws4py
In-Reply-To: <ADF91099-857B-47E0-93F0-6A68E33E8F68@ravnalaska.net>
References: <ADF91099-857B-47E0-93F0-6A68E33E8F68@ravnalaska.net>
Message-ID: <F4D44F8C-3A50-412C-BD36-66320412A1F9@ravnalaska.net>

Ok, let me ask a different question: the impression I have gotten when trying to find help with CherryPy in general and ws4py specifically is that these frameworks are not widely used or well supported. Is that a fair assessment, or do I just have issues that are outside the realm of experience for other users? If it is a fair assessment, should I be looking at a different product for my next project? I know there are a number of options, CherryPy was simply the first one suggested to me, and ws4py is what is listed in their docs as the framework to use for Web Sockets.

Thanks for any feedback that can be provided.
-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------


-------------- next part --------------
 

> On Nov 3, 2015, at 8:05 AM, Israel Brewster <israel at ravnalaska.net> wrote:
> 
> I posted this to the CherryPy and ws4py mailing lists, but in the week since I did that I've only gotten two or three views on each list, and no responses, so as a last-ditch effort I thought I'd post here. Maybe someone with more general python knowledge than me can figure out the traceback and from there a solution.
> 
> Is it possible to use ws4py in conjunction with the cpstats CherryPy tool? I have a CherryPy (3.8.0) web app that uses web sockets via ws4py. Tested and working. I am now trying to get a little more visibility into the functioning of the server, so to that end I enabled the cpstats tool by adding the following line to my '/' configuration:
> 
> tools.cpstats.on=True
> 
> Unfortunately, as soon as I do that, attempts to connect a web socket start failing with the following traceback:
> 
> [28/Oct/2015:08:18:48]  
> Traceback (most recent call last):
>  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 104, in run
>    hook()
>  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 63, in __call__
>    return self.callback(**self.kwargs)
>  File "build/bdist.macosx-10.10-intel/egg/ws4py/server/cherrypyserver.py", line 200, in upgrade
>    ws_conn = get_connection(request.rfile.rfile)
>  File "build/bdist.macosx-10.10-intel/egg/ws4py/compat.py", line 43, in get_connection
>    return fileobj._sock
> AttributeError: 'KnownLengthRFile' object has no attribute '_sock'
> [28/Oct/2015:08:18:48] HTTP 
> Request Headers:
>  PRAGMA: no-cache
>  COOKIE: autoTabEnabled=true; fleetStatusFilterCompany=7H; fleetStatusFilterLocation=ALL; fleetStatusRefreshInterval=5; inputNumLegs=5; session_id=5c8303896aff419c175c79dfadbfdc9d75e6c45a
>  UPGRADE: websocket
>  HOST: flbubble.ravnalaska.net:8088
>  ORIGIN: http://flbubble.ravnalaska.net
>  CONNECTION: Upgrade
>  CACHE-CONTROL: no-cache
>  SEC-WEBSOCKET-VERSION: 13
>  SEC-WEBSOCKET-EXTENSIONS: x-webkit-deflate-frame
>  USER-AGENT: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/601.2.7 (KHTML, like Gecko) Version/9.0.1 Safari/601.2.7
>  SEC-WEBSOCKET-KEY: Szh6Uoe+WzqKR1DgW8JcXA==
>  Remote-Addr: 10.9.1.59
> [28/Oct/2015:08:18:48] HTTP 
> Traceback (most recent call last):
>  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 661, in respond
>    self.hooks.run('before_request_body')
>  File "/Library/Python/2.7/site-packages/CherryPy-3.8.0-py2.7.egg/cherrypy/_cprequest.py", line 114, in run
>    raise exc
> AttributeError: 'KnownLengthRFile' object has no attribute '_sock'
> 
> Disable tools.cpstats.on, and the sockets start working again. Is there some way I can fix this so I can use sockets as well as gather stats from my application? Thanks.
> 
> -----------------------------------------------
> Israel Brewster
> Systems Analyst II
> Ravn Alaska
> 5245 Airport Industrial Rd
> Fairbanks, AK 99709
> (907) 450-7293
> -----------------------------------------------
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list


From ian.g.kelly at gmail.com  Wed Nov  4 16:31:05 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 4 Nov 2015 14:31:05 -0700
Subject: teacher need help!
In-Reply-To: <BLUPR0201MB1524FF0A22E3FD0E8A6439E7D62A0@BLUPR0201MB1524.namprd02.prod.outlook.com>
References: <BLUPR0201MB1524EDBB3F8C367250412FEFD63C0@BLUPR0201MB1524.namprd02.prod.outlook.com>
 <5623397C.40205@timgolden.me.uk>
 <CANy1k1iq-9K_D+iVUW4ErFF5QvByH3r+WMVyHdq2Mrr9nbeNhg@mail.gmail.com>
 <BLUPR0201MB1524A5C40F14DD282BA0A379D63A0@BLUPR0201MB1524.namprd02.prod.outlook.com>
 <5624AC43.3080105@timgolden.me.uk>
 <BLUPR0201MB1524BEDFAD098F598BE43F1ED6390@BLUPR0201MB1524.namprd02.prod.outlook.com>
 <BLUPR0201MB1524FF0A22E3FD0E8A6439E7D62A0@BLUPR0201MB1524.namprd02.prod.outlook.com>
Message-ID: <CALwzidkq7yaaLe3aUREy2hSYxooYXTTpVBqwT9kW6E4P5OckCQ@mail.gmail.com>

On Wed, Nov 4, 2015 at 11:18 AM, Storey, Geneva
<geneva.storey at fultonind.kyschools.us> wrote:
>
>
>
>
> I am having the same problem that we experienced earlier (see below).  This student was exploring random numbers in Python.  She named her program random which caused confusion for her computer.  We deleted the file, but still had the problem.

Was there a lingering .pyc file? The following transcript is from
Linux but still illustrative of the probable cause.

$ echo 'print("Oops!")' > random.py
$ ls random.*
random.py
$ python -c "import random"
Oops!
$ ls random.*
random.py  random.pyc
$ rm random.py
$ python -c "import random"
Oops!
$ rm random.pyc
$ python -c "import random"


> I removed Python from the machine.  When I tried to reinstall, I got the attached error message.  Now it won't even install.  Any suggestions would be greatly appreciated!

Unfortunately the attachment doesn't seem to have made it through.
Also, many of the subscribers here read this mailing list as a Usenet
group and wouldn't be able to see the attachment anyway. Please copy
and paste the error instead.


From input/ldompeling at casema.nl  Wed Nov  4 16:44:45 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Wed, 04 Nov 2015 21:44:45 GMT
Subject: raw_input and break
Message-ID: <h%u_x.29450$bN3.2901@fx06.am1>

I have an continues loop with "while True:"
Now I want to use "raw_input" and when I press "s" on the keybord that it will 
"break" the continues loop.

I tried:
choices = raw_input
if choises == s:
break

But even when I not press "s" it "break"
I want that I not press "s" the script continues.

Any ideas ?

Thanks



-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From ian.g.kelly at gmail.com  Wed Nov  4 16:54:36 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 4 Nov 2015 14:54:36 -0700
Subject: raw_input and break
In-Reply-To: <h%u_x.29450$bN3.2901@fx06.am1>
References: <h%u_x.29450$bN3.2901@fx06.am1>
Message-ID: <CALwzid=du91Mu2rJ5AJCRD+2yong=8OdnPZfqHxZAkfuji_-3Q@mail.gmail.com>

On Wed, Nov 4, 2015 at 2:44 PM,  <input/ldompeling at casema.nl> wrote:
> I have an continues loop with "while True:"
> Now I want to use "raw_input" and when I press "s" on the keybord that it will
> "break" the continues loop.
>
> I tried:
> choices = raw_input

This doesn't call raw_input. For that you need to write raw_input(),
where the parentheses indicate a function call. All the above does is
find the raw_input function and assign that function to the name
"choices".

> if choises == s:

Strings in Python are delimited with quotes: "s", not just s. The
latter is going to try to look up a variable named s, not denote a
string. Also, it's important to spell the variable here in the same
way that you did above. Above you have a c where here there is an s.
I'm assuming that this isn't exactly what you ran, because you most
likely would have gotten a NameError here. Please copy and paste
exactly the code that you're trying to run rather than retyping it.

> break

This needs to be indented. Not indenting it would be a SyntaxError, so
again I'm guessing that this isn't actually what you ran.


From joel.goldstick at gmail.com  Wed Nov  4 16:56:40 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Wed, 4 Nov 2015 16:56:40 -0500
Subject: raw_input and break
In-Reply-To: <h%u_x.29450$bN3.2901@fx06.am1>
References: <h%u_x.29450$bN3.2901@fx06.am1>
Message-ID: <CAPM-O+x-cicYTAH42-1H7ePOPXgKrM-CYo4VtH2NgctTSPO4Pg@mail.gmail.com>

On Wed, Nov 4, 2015 at 4:44 PM, <input/ldompeling at casema.nl> wrote:

> I have an continues loop with "while True:"
> Now I want to use "raw_input" and when I press "s" on the keybord that it
> will
> "break" the continues loop.
>
> I tried:
> choices = raw_input
> if choises == s:
> break
>
> But even when I not press "s" it "break"
> I want that I not press "s" the script continues.
>
> Any ideas ?
>

You need to quote the s:
if choices == 's'

you need to check your spelling -- you have choices and choises

You need to indent break 4 spaces

>
> Thanks
>
>
>
> --
> --------------------------------- --- -- -
> Posted with NewsLeecher v7.0 Beta 2
> Web @ http://www.newsleecher.com/?usenet
> ------------------- ----- ---- -- -
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From input/ldompeling at casema.nl  Wed Nov  4 17:37:21 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Wed, 04 Nov 2015 22:37:21 GMT
Subject: raw_input and break
References: <mailman.30.1446674207.16136.python-list@python.org>
Message-ID: <BMv_x.23349$_R5.7764@fx07.am1>

In reply to "Joel Goldstick" who wrote the following:

> On Wed, Nov 4, 2015 at 4:44 PM, <input/ldompeling at casema.nl> wrote:
> 
> > I have an continues loop with "while True:"
> > Now I want to use "raw_input" and when I press "s" on the keybord that it
> > will
> > "break" the continues loop.
> > 
> > I tried:
> > choices = raw_input
> > if choises == s:
> > break
> > 
 You need to quote the s:
> if choices == 's'

I quote the s, but its still break even when I not press the s.

--------------------------------------------------------------

>But even when I not press "s" it "break"
> > I want that I not press "s" the script continues.
> > 
> > Any ideas ?
> > 
> 
> You need to quote the s:
> if choices == 's'
> 
> you need to check your spelling -- you have choices and choises
> 
> You need to indent break 4 spaces
> 
> > 
> > Thanks
> > 
> > 
> > 
> > --
> > --------------------------------- --- -- -
> > Posted with NewsLeecher v7.0 Beta 2
> > Web @ http://www.newsleecher.com/?usenet
> > ------------------- ----- ---- -- -
> > 
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> > 
> 
> 
> 
> --
> Joel Goldstick
> http://joelgoldstick.com/stats/birthdays




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From tjreedy at udel.edu  Wed Nov  4 17:52:30 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 4 Nov 2015 17:52:30 -0500
Subject: Bugfixing python 3.5 asyncio
In-Reply-To: <CA+eiJG2Puii8xmVjK9vZF_XrKwNrTaiYNqtrzHk8uakGpu8AYA@mail.gmail.com>
References: <CA+eiJG2Puii8xmVjK9vZF_XrKwNrTaiYNqtrzHk8uakGpu8AYA@mail.gmail.com>
Message-ID: <n1e27g$gs0$1@ger.gmane.org>

On 11/3/2015 8:24 PM, Dmitry Panteleev wrote:
> Hello,
>
> There is a bug in asyncio.Queue
> (https://github.com/python/asyncio/issues/268), which makes it
> unusable for us. It is fixed in master now.

I presume that the fix has been merged into the CPython repository (you 
could check).  If so, it should be included when 3.5.1 is released in 
about a month+.

> What is the easiest way to
> patch the asyncio bundled with python if I have to distribute it among
> 5 colleagues? It is used in our private module.

The cleanest way -- in my opinion -- would be to patch your 3.5.0 
installations, making them '3.5.0+'.  For 5 installations,

> I can think of:
> 1. Copy asyncio.queues into our package so it has a different name

this would be easiest, but then I would retest and presumably revise and 
redistribute after 3.5.1 is out

> 2. Override sys.path
>
> Both look really strange. Is there anything else?

What I said above.

-- 
Terry Jan Reedy



From emile at fenx.com  Wed Nov  4 17:59:43 2015
From: emile at fenx.com (Emile van Sebille)
Date: Wed, 4 Nov 2015 14:59:43 -0800
Subject: any practise site about python?
In-Reply-To: <4b7392fb-8639-49d2-a09d-a06bbbcbcff7@googlegroups.com>
References: <4b7392fb-8639-49d2-a09d-a06bbbcbcff7@googlegroups.com>
Message-ID: <n1e2l0$lpd$1@ger.gmane.org>

On 11/4/2015 11:38 AM, alperen wrote:
> hi guys.
> i am computer engineering student and i want to practise the lectures that i saw at school. for example dictionaries tuples or some other topics. i know eulerproject but it is hard for starting. do you know any exercise sites for students or beginners
>

Any of the top four hits googling 'getting started with python' should 
provide you a thread to pull on.

Emile




From Seymore4Head at Hotmail.invalid  Wed Nov  4 18:00:12 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Wed, 04 Nov 2015 18:00:12 -0500
Subject: Regular expressions
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
Message-ID: <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>

On Wed, 04 Nov 2015 08:13:51 -0700, Michael Torrie <torriem at gmail.com>
wrote:

>On 11/04/2015 01:57 AM, Peter Otten wrote:
>> and then headed for the man page. Apparently there is a subset
>> called "basic regular expressions":
>>
>> """>   Basic vs Extended Regular Expressions
>>        In basic regular expressions the meta-characters ?, +, {, |, (,
>>        and ) lose their special meaning; instead use  the  backslashed
>>        versions \?, \+, \{, \|, \(, and \).
>> """
>
>Good catch. I think this must have been what my brain was thinking when
>I commented about grep and regular expressions earlier. I checked the
>man page but didn't read down far enough.
>
>I was still technically wrong though.
>
>It's neat to learn so much on these tangents that the python list goes
>on frequently. Hope the OP is still lurking, reading all these comments,
>though I suspect he's not.
>
I am still here, but I have to admit I am not picking up too much.


From tjreedy at udel.edu  Wed Nov  4 18:00:22 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 4 Nov 2015 18:00:22 -0500
Subject: Unbuffered stderr in Python 3
In-Reply-To: <56397921$0$11094$c3e8da3@news.astraweb.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
 <pan.2015.11.03.07.10.58.482000@nowhere.invalid>
 <874mh39lgu.fsf@fastmail.com>
 <CAPTjJmqDMkq3Q9ztaSLFUbJ=CK2dL=Od+JL=kxXavytEXVWYVQ@mail.gmail.com>
 <mailman.1.1446589565.20590.python-list@python.org>
 <56397921$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <n1e2m7$gs0$2@ger.gmane.org>

On 11/3/2015 10:18 PM, Steven D'Aprano wrote:
> On Wednesday 04 November 2015 09:25, Terry Reedy wrote:
>
>> On 11/3/2015 10:42 AM, Chris Angelico wrote:
>>> On Wed, Nov 4, 2015 at 2:00 AM, Random832 <random832 at fastmail.com> wrote:
>>>> Nobody <nobody at nowhere.invalid> writes:
>>>>
>>>>> It's probably related to the fact that std{in,out,err} are Unicode
>>>>> streams.
>>>>
>>>> There's no fundamental reason a Unicode stream should have to be line
>>>> buffered. If it's "related", it's only in that an oversight was made in
>>>> the course of making that change.
>>
>> The current behavior is not an 'oversight'.  I was considered, decided,
>> and revisited in https://bugs.python.org/issue13601.  Guido:
>> "Line-buffering should be good enough since in practice errors messages
>> are always terminated by a newline."  If not, print(part_line,
>> file=sys.stderr, flush=True) works for the unusual case.
>
> This is one of the offending line from our code base:
>
> print('<4>Suspicious answer "{}"!'.format(answer), file=sys.stderr)
>
> So that ought to be terminated by a newline.

Or include 'flush=True' if you really want that to be a partial line.

-- 
Terry Jan Reedy



From Seymore4Head at Hotmail.invalid  Wed Nov  4 18:02:40 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Wed, 04 Nov 2015 18:02:40 -0500
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
Message-ID: <1i3l3b9836hatsuoopak5gtg2c38g49kb1@4ax.com>

On Wed, 04 Nov 2015 14:48:21 +1100, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:

>On Wednesday 04 November 2015 11:33, rurpy at yahoo.com wrote:
>
>>> Not quite.  Core language concepts like ifs, loops, functions,
>>> variables, slicing, etc are the socket wrenches of the programmer's
>>> toolbox.  Regexs are like an electric impact socket wrench.  You can do
>>> the same work without it, but in many cases it's slower. But you have to
>>> learn the other hand tools first in order to really use the electric
>>> driver properly (understanding torques, direction of threads, etc), lest
>>> you wonder why you're breaking off so many bolts with the torque of the
>>> impact drive.
>> 
>> I consider regexs more fundemental
>
>I'm sure that there are people who consider the International Space Station 
>more fundamental than the lever, the wedge and the hammer, but they would be 
>wrong too.
>
>Given primitives for branching, loops and variables, you can build support 
>for regexes. Given regexes, how would you build support for variables?
>
>Of course, you could easily prove me wrong. All you would need to do to 
>demonstrate that regexes are more fundamental than branching, loops and 
>variables would be to demonstrate that the primitive operations available in 
>commonly used CPUs are regular expressions, and that (for example) C's for 
>loop and if...else are implemented in machine code as regular expressions, 
>rather than the other way around.

So far the only use I have for regex is to replace slicing, but I
think it is an improvement.


From dpantele at dpantele.com  Wed Nov  4 18:08:41 2015
From: dpantele at dpantele.com (Dmitry Panteleev)
Date: Wed, 4 Nov 2015 18:08:41 -0500
Subject: Bugfixing python 3.5 asyncio
In-Reply-To: <n1e27g$gs0$1@ger.gmane.org>
References: <CA+eiJG2Puii8xmVjK9vZF_XrKwNrTaiYNqtrzHk8uakGpu8AYA@mail.gmail.com>
 <n1e27g$gs0$1@ger.gmane.org>
Message-ID: <CA+eiJG2K98Bc=mUnGMLAE7zfW75Oqpn2-d98Vt=sEbksVz6j_Q@mail.gmail.com>

Hello,

Yes, the fix has been merged. If 3.5.1 gets released in a month, it
should not be a problem. And looks like it dpends on
http://bugs.python.org/issue25446 .

Thank you for the information.
Dmitry

On Wed, Nov 4, 2015 at 5:52 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> On 11/3/2015 8:24 PM, Dmitry Panteleev wrote:
>>
>> Hello,
>>
>> There is a bug in asyncio.Queue
>> (https://github.com/python/asyncio/issues/268), which makes it
>> unusable for us. It is fixed in master now.
>
>
> I presume that the fix has been merged into the CPython repository (you
> could check).  If so, it should be included when 3.5.1 is released in about
> a month+.
>
>> What is the easiest way to
>> patch the asyncio bundled with python if I have to distribute it among
>> 5 colleagues? It is used in our private module.
>
>
> The cleanest way -- in my opinion -- would be to patch your 3.5.0
> installations, making them '3.5.0+'.  For 5 installations,
>
>> I can think of:
>> 1. Copy asyncio.queues into our package so it has a different name
>
>
> this would be easiest, but then I would retest and presumably revise and
> redistribute after 3.5.1 is out
>
>> 2. Override sys.path
>>
>> Both look really strange. Is there anything else?
>
>
> What I said above.
>
> --
> Terry Jan Reedy
>
> --
> https://mail.python.org/mailman/listinfo/python-list



-- 
Best Regards,
Dmitry Panteleev


From tjreedy at udel.edu  Wed Nov  4 18:08:51 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 4 Nov 2015 18:08:51 -0500
Subject: Regular expressions
In-Reply-To: <56397a18$0$11094$c3e8da3@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
Message-ID: <n1e364$gs0$3@ger.gmane.org>

On 11/3/2015 10:23 PM, Steven D'Aprano wrote:

> I don't even know what grep stands for.

Get Regular Expression & Print

-- 
Terry Jan Reedy



From joel.goldstick at gmail.com  Wed Nov  4 18:24:43 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Wed, 4 Nov 2015 18:24:43 -0500
Subject: any practise site about python?
In-Reply-To: <n1e2l0$lpd$1@ger.gmane.org>
References: <4b7392fb-8639-49d2-a09d-a06bbbcbcff7@googlegroups.com>
 <n1e2l0$lpd$1@ger.gmane.org>
Message-ID: <CAPM-O+wDM3fo__UT4iuehPBqoX6Zox=B27suwktYCwPHKbh8rA@mail.gmail.com>

On Wed, Nov 4, 2015 at 5:59 PM, Emile van Sebille <emile at fenx.com> wrote:

> On 11/4/2015 11:38 AM, alperen wrote:
>
>> hi guys.
>> i am computer engineering student and i want to practise the lectures
>> that i saw at school. for example dictionaries tuples or some other topics.
>> i know eulerproject but it is hard for starting. do you know any exercise
>> sites for students or beginners
>>
>>
> Any of the top four hits googling 'getting started with python' should
> provide you a thread to pull on.
>
> Emile
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>

The python tutorial at python.org is good.  Also, python the hard way is
good.


-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From Seymore4Head at Hotmail.invalid  Wed Nov  4 18:29:51 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Wed, 04 Nov 2015 18:29:51 -0500
Subject: Regular expressions
References: <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.34.1446678541.16136.python-list@python.org>
Message-ID: <r65l3b11bf221ucuisd4gcbppgc9qb6mfl@4ax.com>

On Wed, 4 Nov 2015 18:08:51 -0500, Terry Reedy <tjreedy at udel.edu>
wrote:

>On 11/3/2015 10:23 PM, Steven D'Aprano wrote:
>
>> I don't even know what grep stands for.
>
>Get Regular Expression & Print

Thanks,  I may get around to that eventually.


From Seymore4Head at Hotmail.invalid  Wed Nov  4 18:30:23 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Wed, 04 Nov 2015 18:30:23 -0500
Subject: OT ish    History Channel - The Invention of the Internet
Message-ID: <k75l3b5knql5ve4fgpeeke5v9pqd27ppmk@4ax.com>

https://www.youtube.com/watch?v=M9ebkjWU6Z4


From rurpy at yahoo.com  Wed Nov  4 19:13:58 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 16:13:58 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.18.1446648732.16136.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
Message-ID: <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>

On 11/04/2015 07:52 AM, Chris Angelico wrote:
> On Thu, Nov 5, 2015 at 1:38 AM, rurpy wrote:
>> I'm afraid you are making a category error but perhaps that's in
>> part because I wasn't clear.  I was not talking about computer
>> science.  I was talking about human beings learning about computers.
>> Most people I know consider programming to be a higher level activity
>> than "using" a computer: editing, sending email etc.  Many computer
>> users (not programmers) learn to use regular expressions as part
>> of using a computer without knowing anything about programming.
>> It was on that basis I called them more fundamental -- something
>> learned earlier which is expanded on and added to later.  But you
>> have a bit of a point, perhaps "fundamental" was not the best choice
>> of word to communicate that.
>
> The "fundamentals" of something are its most basic functions, not its
> most basic uses. The most common use of a computer might be to browse
> the web, but the fundamental functionality is arithmetic and logic.

If one accepted that then one would have to reject the term "fundamental 
use" as meaningless.  A quick trip to google shows that's not true.

> Setting aside the choice of word, though, I still don't think regular
> expressions are a more basic use of computing than loops and
> conditionals. A regex can't be used for anything other than string
> matching; they exist for one purpose, and one purpose only: to answer
> the question "Does this string match this pattern?". 

But string matching *is* a fundamental problem that arises frequently
in many aspects of CS, programming and, as I mentioned, day-to-day
computer use.  Saying its "only" for pattern matching is like saying 
floating point numbers are "only" for doing non-integer arithmetic,
or unicode is "only" for representing text.  (Neither of those is a 
good analogy because both lack the important theoretical underpinnings 
that regular expressions have [*]).
There would be far fewer computer languages, and they would be much
more primitive if regular expressions (and the fundamental concepts
that they express) did not exist.

To be sure, I did gloss over Michael Torries' point that there are 
other concepts that are more basic in the context of learning 
programming, he was correct about that. 

But that does not negate the fact that regexes are important and 
fundamental.  They are both very useful in a practical sense (they 
are even available in Microsoft Excel) and important in a theoretical 
sense.  You are not well rounded as a programmer if you decline to 
learn about regular expressions because "they are too cryptic", or 
"I can do in code anything they do".  

I think the constant negative reception the posters receive here when
they ask about regexes does them a great disservice.

By all means point out that python offers a number of functions that 
can avoid the need for using regexes in simple cases.  Even point out 
that you (the plural you) don't like them and prefer other solutions
(like writing code that does the same thing in a more half-assed bug
ridden way, the posts in this thread being a case in point.)

But I really wish every mention of regexes here wasn't reflexively 
greeted with a barrage of negative comments and that lame "two problems"
quote, especially without an answer to the poster's regex question.

> Sure, you can
> abuse that into a primality check and other forms of crazy arithmetic,
> but it's not what they truly do. I also would not teach regexes to
> people as part of an "introduction to computing" course, any more than
> I would teach the use of Microsoft Excel, which some such courses have
> been known to do. (And no, it's not because of the Microsoftness. I
> wouldn't teach LibreOffice Calc either.) You don't need to know how to
> work a spreadsheet as part of the basics of computer usage, and you
> definitely don't need an advanced form of text search.

Seems to me that clearly depends on the intent of the class, the students
goal's, what they'll be studying after the class, what their current 
level of knowledge is, etc.  Your scenario seems way too under-specified
to say anything definitive.  And further, the pedagogy of CS (or of any 
subject of education) is not "settled science" and that kind of question
almost never has a clear right/wrong answer.

This list is not a class.  If someone comes here with a question about 
Python's regexes they deserve an answer and not be bombarded with reasons
why they shouldn't be using regexes beyond mentioning some of the alternatives
in a "oh, by the way" way.  (And yes, I recognize in this case the OP did 
get a good answer from MRAB early on.)

----
[*] yes, I know there is a lot of CS theory underlying floating point.
I don't think it is as deep or as important as that underlying regexes,
automata and language.


From rurpy at yahoo.com  Wed Nov  4 19:24:27 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 16:24:27 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
Message-ID: <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>

On Wednesday, November 4, 2015 at 4:05:06 PM UTC-7, Seymore4Head wrote:
>[...]
> I am still here, but I have to admit I am not picking up too much.

The "take away" I recommend is: the folks here are often way 
overly negative regarding regular expressions and that you not
ignore them, but take them with a BIG grain of salt and continue 
learning about and using regexs.

You will find they are an indispensable tool, not just in Python 
programming but in many aspects of computer use.


From rosuav at gmail.com  Wed Nov  4 19:33:45 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 11:33:45 +1100
Subject: Regular expressions
In-Reply-To: <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
Message-ID: <CAPTjJmq5A-5fvyCsoZGgWjcGdTG8dAPg3_tCeTxQGnPxnhxtjg@mail.gmail.com>

On Thu, Nov 5, 2015 at 11:13 AM, rurpy--- via Python-list
<python-list at python.org> wrote:
> On 11/04/2015 07:52 AM, Chris Angelico wrote:
>> On Thu, Nov 5, 2015 at 1:38 AM, rurpy wrote:
>>> I'm afraid you are making a category error but perhaps that's in
>>> part because I wasn't clear.  I was not talking about computer
>>> science.  I was talking about human beings learning about computers.
>>> Most people I know consider programming to be a higher level activity
>>> than "using" a computer: editing, sending email etc.  Many computer
>>> users (not programmers) learn to use regular expressions as part
>>> of using a computer without knowing anything about programming.
>>> It was on that basis I called them more fundamental -- something
>>> learned earlier which is expanded on and added to later.  But you
>>> have a bit of a point, perhaps "fundamental" was not the best choice
>>> of word to communicate that.
>>
>> The "fundamentals" of something are its most basic functions, not its
>> most basic uses. The most common use of a computer might be to browse
>> the web, but the fundamental functionality is arithmetic and logic.
>
> If one accepted that then one would have to reject the term "fundamental
> use" as meaningless.  A quick trip to google shows that's not true.

A quick trip to Google showed me that there are a number of uses of
the phrase, mostly in scientific papers and such. I've no idea how
that helps your argument.

> But string matching *is* a fundamental problem that arises frequently
> in many aspects of CS, programming and, as I mentioned, day-to-day
> computer use.  Saying its "only" for pattern matching is like saying
> floating point numbers are "only" for doing non-integer arithmetic,
> or unicode is "only" for representing text.  (Neither of those is a
> good analogy because both lack the important theoretical underpinnings
> that regular expressions have [*]).

String matching does happen a lot. How often do you actually need
pattern matching? Most of the time, you're doing equality checks - or
prefix/suffix checks, at best.

> There would be far fewer computer languages, and they would be much
> more primitive if regular expressions (and the fundamental concepts
> that they express) did not exist.

So? There would also be far fewer computer languages if braces didn't
exist, because we wouldn't have the interminable arguments about
whether they're good or not.

> To be sure, I did gloss over Michael Torries' point that there are
> other concepts that are more basic in the context of learning
> programming, he was correct about that.
>
> But that does not negate the fact that regexes are important and
> fundamental.  They are both very useful in a practical sense (they
> are even available in Microsoft Excel) and important in a theoretical
> sense.  You are not well rounded as a programmer if you decline to
> learn about regular expressions because "they are too cryptic", or
> "I can do in code anything they do".

You've proven that they are important, but in no way have you proven
them fundamental. A regular expression library is the ideal solution
to the problem "I want to let my users search for patterns of their
own choosing". That's great, but it's only one specific class of
problem.

> I think the constant negative reception the posters receive here when
> they ask about regexes does them a great disservice.
>
> By all means point out that python offers a number of functions that
> can avoid the need for using regexes in simple cases.  Even point out
> that you (the plural you) don't like them and prefer other solutions
> (like writing code that does the same thing in a more half-assed bug
> ridden way, the posts in this thread being a case in point.)
>
> But I really wish every mention of regexes here wasn't reflexively
> greeted with a barrage of negative comments and that lame "two problems"
> quote, especially without an answer to the poster's regex question.

When has that happened? Usually there'll be at least two answers - one
that uses a regex and one that doesn't - and people get to read both.

>> Sure, you can
>> abuse that into a primality check and other forms of crazy arithmetic,
>> but it's not what they truly do. I also would not teach regexes to
>> people as part of an "introduction to computing" course, any more than
>> I would teach the use of Microsoft Excel, which some such courses have
>> been known to do. (And no, it's not because of the Microsoftness. I
>> wouldn't teach LibreOffice Calc either.) You don't need to know how to
>> work a spreadsheet as part of the basics of computer usage, and you
>> definitely don't need an advanced form of text search.
>
> Seems to me that clearly depends on the intent of the class, the students
> goal's, what they'll be studying after the class, what their current
> level of knowledge is, etc.  Your scenario seems way too under-specified
> to say anything definitive.  And further, the pedagogy of CS (or of any
> subject of education) is not "settled science" and that kind of question
> almost never has a clear right/wrong answer.

Uhh, "introduction to computing". What's the current level of
knowledge? Close to zero. That's the whole point of an introductory
class. It's a place where you teach the basics.

> This list is not a class.  If someone comes here with a question about
> Python's regexes they deserve an answer and not be bombarded with reasons
> why they shouldn't be using regexes beyond mentioning some of the alternatives
> in a "oh, by the way" way.  (And yes, I recognize in this case the OP did
> get a good answer from MRAB early on.)

"I want to swim from Sydney to Los Angeles, but my gloves keep wearing
out half way across the Pacific. How can I make my gloves strong
enough to get me to LA?"

Response 1: "If you use industrial-strength gloves and go via Papua
New Guinea, you can double up the gloves and swim to LA."

Response 2: "Swimming across the Pacific is a bad idea. Have you
considered taking a boat or plane instead?"

Which is the more helpful response? You can go ahead and assume the OP
always knows best; I'm going to at least offer some alternatives.

ChrisA


From rosuav at gmail.com  Wed Nov  4 19:34:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 11:34:26 +1100
Subject: Regular expressions
In-Reply-To: <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
Message-ID: <CAPTjJmrsqPB_GnEY6CPE==zQQYrM-+Fqys9uc626fCDQbP+aSw@mail.gmail.com>

On Thu, Nov 5, 2015 at 11:24 AM, rurpy--- via Python-list
<python-list at python.org> wrote:
> On Wednesday, November 4, 2015 at 4:05:06 PM UTC-7, Seymore4Head wrote:
>>[...]
>> I am still here, but I have to admit I am not picking up too much.
>
> The "take away" I recommend is: the folks here are often way
> overly negative regarding regular expressions and that you not
> ignore them, but take them with a BIG grain of salt and continue
> learning about and using regexs.
>
> You will find they are an indispensable tool, not just in Python
> programming but in many aspects of computer use.

The "take away" that I recommend is: Rurpy loves to argue in favour of
regular expressions, but as you can see from the other posts, there
are alternatives, which are often FAR superior.

ChrisA


From rosuav at gmail.com  Wed Nov  4 19:42:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 11:42:41 +1100
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <n1dmn7$fnq$1@dont-email.me>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
Message-ID: <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>

On Thu, Nov 5, 2015 at 6:38 AM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> Am 04.11.15 um 19:24 schrieb Ben Finney:
>>
>> The name is a mnemonic for a compound command in ?ed? [0], a text editor
>> that pre-dates extravagant luxuries like ?presenting a full screen of
>> text at one time?.
>>
>>  [... lots of fun facts ...]
>
>
> Here is another fun fact: The convincing UI of ed was actually so widely
> applied, that even Microsoft included a similar editor into MSDOS, called
> EDLIN. EDLIN, of course, was a bastardized version of ed that could do much
> less and also lacked regular expressions. Needless to say that the mighty
> "VIsual" editor was out 5 years before MSDOS shipped EDLIN as the only
> editor...
>
> In contrast to ed, the stream editor "sed" is used multiple times avery day
> in a typical Unix session inside shell scripts to perform automated text
> processing tasks, including regex replacement.

As someone who grew up on MS-DOS, I'd like to mention that EDLIN's
value wasn't in the obvious places. There were two features it had
that most other editors didn't: firstly, it would read only as much of
the file as it needed, so you could edit a file larger than available
memory; and secondly, all commands came from stdin, which could be
redirected - making it a poor man's 'sed'. Using EDLIN for regular
file editing was never the normal thing.

Fast forward a decade or two, and I'm working on a MUD server for a
friend. It incorporates an editor that can be used on a dumb telnet
connection - and it's line based again. So there's clearly some value
here :) Visual editors get the lion's share of actual editing work,
but in special circumstances, it is nice to have a quick little
ed-like program around.

ChrisA


From steve at pearwood.info  Wed Nov  4 19:44:39 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 11:44:39 +1100
Subject: raw_input and break
References: <mailman.30.1446674207.16136.python-list@python.org>
 <BMv_x.23349$_R5.7764@fx07.am1>
Message-ID: <563aa679$0$1608$c3e8da3$5496439d@news.astraweb.com>

On Thu, 5 Nov 2015 09:37 am, input/ldompeling at casema.nl wrote:

> I quote the s, but its still break even when I not press the s.

The code you have shown us is so full of bugs and typos that you cannot
possibly be running that code.

Unfortunately, we do not have magical powers. We cannot see the code you
*actually* run, only the code you show us. So if you want help, you need to
show us the code you actually run.

COPY AND PASTE -- do not retype from memory -- the while loop from your
code. Make sure it will run on its own. If you can't run the code, because
it lacks variables or something else, neither can we.

Help us to help you. We cannot help you unless you show us the code you are
running.



-- 
Steven



From steve at pearwood.info  Wed Nov  4 19:54:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 11:54:20 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <1i3l3b9836hatsuoopak5gtg2c38g49kb1@4ax.com>
Message-ID: <563aa8be$0$1596$c3e8da3$5496439d@news.astraweb.com>

On Thu, 5 Nov 2015 10:02 am, Seymore4Head wrote:

> So far the only use I have for regex is to replace slicing, but I
> think it is an improvement.

I don't understand this. This is like saying "so far the only use I have for
a sandwich press is to replace my coffee pot". Regular expressions and
slicing do very different things.

Slicing extracts substrings, given known starting and ending positions:


py> the_str = "Now is the time for all good men..."
py> the_str[7:12]
'the t'


Regular expressions don't extract substrings with known start/end positions.
They *find* matching text, giving a search string with metacharacters. (If
there are no metacharacters in your search string, you shouldn't use a
regex. str.find will be significantly faster and more convenient.)

Slicing is not about finding text, it is about extracting text once you've
already found it. So they are complementary, not alternatives.



-- 
Steven



From steve at pearwood.info  Wed Nov  4 21:24:25 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 13:24:25 +1100
Subject: Regular expressions
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
Message-ID: <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Thu, 5 Nov 2015 11:24 am, rurpy at yahoo.com wrote:

> You will find they are an indispensable tool, not just in Python
> programming but in many aspects of computer use.

You will find them a useful tool, but not indispensable by any means.

Hint:

- How many languages make arithmetic a built-in part of the language? Almost
all of them. I don't know of any language that doesn't let you express
something like "1 + 1" using built-in functions or syntax. Arithmetic is
much closer to indispensable.

- How many languages make regular expressions a built-in part of the
language? Almost none of them. There's Perl, obviously, and its
predecessors sed and awk, and probably a few others, but most languages
relegate regular expressions to a library.

- How many useful programs can be written with regexes? Clearly there are
many. Some of them would even be quite difficult without regexes. (In
effect, you would have to invent your own pattern-matching code.)

- How many useful programs can be written without regexes? Clearly there are
also many. Every time you write a Python program and fail to import re,
you've written one.

Can you call yourself a well-rounded programmer without at least a basic
understanding of some regex library? Well, probably not. But that's part of
the problem with regexes. They have, to some degree, driven out potentially
better -- or at least differently bad -- pattern matching solutions, such
as (E)BNF grammars, SNOBOL pattern matching, or lowly globbing patterns. Or
even alternative idioms, like Hypercard's "chunking" idioms.

When all you have is a hammer, everything looks like a nail.





-- 
Steven



From steve at pearwood.info  Wed Nov  4 21:26:55 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 13:26:55 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
Message-ID: <563abe6f$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Thu, 5 Nov 2015 11:13 am, rurpy at yahoo.com wrote:

> There would be far fewer computer languages, and they would be much
> more primitive if regular expressions (and the fundamental concepts
> that they express) did not exist.

Well, that's certainly true. But only because contra-factual statements can
imply the truth of anything. If squares had seven sides, then Joseph Stalin
would have been the first woman to go to the moon on horseback.

I can't imagine a world where pattern matching doesn't exist. That's like
trying to imagine a world where arithmetic doesn't exist. But I think we
can safely say that, had nobody thought of the idea of searching for
patterns ('find me all the lines with "green" in them'), there would be far
fewer regex libraries in existence. I doubt that there would be "far fewer"
programming languages. With the possible exception of Perl, sed and awk,
I'm not aware of any languages which were specifically inspired by, and
exist primarily to apply, regular expressions, nor any languages which
*require* regexes in their implementation. Most languages are built on
parsers, not regular expressions.


> But I really wish every mention of regexes here wasn't reflexively 
> greeted with a barrage of negative comments and that lame "two problems"
> quote, especially without an answer to the poster's regex question.

I don't disagree with this. Certainly we should accept questions from people
who are simply trying to learn how to use regexes without bombarding them
with admonitions to do something different. Yes yes, I know that regexes
aren't the only tool in my tool box, but *right now* I want to learn how to
use regexes.



-- 
Steven



From steve at pearwood.info  Wed Nov  4 21:28:49 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 13:28:49 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
Message-ID: <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Wed, 4 Nov 2015 07:57 pm, Peter Otten wrote:

> I tried Tim's example
> 
> $ seq 5 | grep '1*'
> 1
> 2
> 3
> 4
> 5
> $

I don't understand this. What on earth is grep matching? How does "4"
match "1*"?


> which surprised me because I remembered that there usually weren't any
> matching lines when I invoked grep instead of egrep by mistake. So I tried
> another one
> 
> $ seq 5 | grep '[1-3]+'
> $
> 
> and then headed for the man page. Apparently there is a subset called
> "basic regular expressions":
> 
> """
>   Basic vs Extended Regular Expressions
>        In basic regular expressions the meta-characters ?, +, {, |, (,
>        and ) lose their special meaning; instead use  the  backslashed
>        versions \?, \+, \{, \|, \(, and \).
> """

None of this appears relevant, as the metacharacter * is not listed. So
what's going on?




-- 
Steven



From python.list at tim.thechases.com  Wed Nov  4 21:48:15 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 4 Nov 2015 20:48:15 -0600
Subject: Regular expressions
In-Reply-To: <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <20151104204815.4263e11c@bigbox.christie.dr>

On 2015-11-05 13:28, Steven D'Aprano wrote:
> > I tried Tim's example
> > 
> > $ seq 5 | grep '1*'
> > 1
> > 2
> > 3
> > 4
> > 5
> > $  
> 
> I don't understand this. What on earth is grep matching? How does
> "4" match "1*"?

The line with "4" matches "zero or more 1s".  If it was searching for
a literal "1*" (as would happen with fgrep or "grep -F"), it would
return no results:

  $ seq 5 | fgrep '1*'
  $

-tkc





From ben+python at benfinney.id.au  Wed Nov  4 22:03:45 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 05 Nov 2015 14:03:45 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <85pozpjgfi.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> On Wed, 4 Nov 2015 07:57 pm, Peter Otten wrote:
>
> > I tried Tim's example
> > 
> > $ seq 5 | grep '1*'
> > 1
> > 2
> > 3
> > 4
> > 5
> > $
>
> I don't understand this. What on earth is grep matching? How does "4"
> match "1*"?

You can experiment with regular expressions to find out. Here's a link
to the RegExr tool for the above pattern <URL:http://regexr.com/3c4ot>.

Matching patterns can include specifications meaning ?match some number
of the preceding segment?, with the ?{n,m}? notation. That means ?match
at least n, and at most m, occurrences of the preceding segment?. Either
?n? or ?m? can be omitted, meaning ?at least 0? and ?no maximum?
respectively.

Those are quite useful, so there are shortcuts for the most common
cases: ??? is a short cut for ?{0,1}?, ?*? is a short cut for ?{0,}?,
and ?+? is a short cut for ?{1,}?.

In this case, ?*? is a short cut for ?{0,}? meaning ?match 0 or more
occurences of the preceding segment?. The segment here is the atom ?1?.
Since ?1*? is the entirety of the pattern, the pattern can match zero
characters, anywhere within any string. So, it matches every possible
string.

To match (some atom) 1 or more times, ?+? is a short cut for ?(1,}?
meaning ?match 1 or more occurrences of the preceding segment?.

-- 
 \    ?????????????? (To study and not think is a waste. |
  `\                             To think and not study is dangerous.) |
_o__)                            ???? Confucius (551 BCE ? 479 BCE) |
Ben Finney



From ben+python at benfinney.id.au  Wed Nov  4 22:07:16 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 05 Nov 2015 14:07:16 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
 <563abe6f$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <85lhadjg9n.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> Yes yes, I know that regexes aren't the only tool in my tool box, but
> *right now* I want to learn how to use regexes.

I'll gently suggest this isn't a particularly good forum to do so.

Learn them with a tool like <URL:http://www.regexr.com/> and a tutorial
<URL:http://www.usna.edu/Users/cs/wcbrown/regexp/RegexpTutorial.html> or
something longer.

-- 
 \                ?Fascism is capitalism plus murder.? ?Upton Sinclair |
  `\                                                                   |
_o__)                                                                  |
Ben Finney



From zljubisic at gmail.com  Wed Nov  4 22:41:38 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Wed, 4 Nov 2015 19:41:38 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <n18fmg$oj6$1@reader1.panix.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
Message-ID: <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>

> The best way is probably to do nothing at all, and let the caller handle
> any exceptions.

In that case every call of the get_html function has to be in the try/except block with many exceptions.
Sometimes, it is enough just to know whether I managed to get the html or not.
In that case, I could for example, in get_html have try/except block which will as result raise let's say NoHtml custom exception or return some special value.

Raising an exception forces me to put every call of the get_html function in try/except block.
If I am returning a special value, than I can call get_html and then test the value.

I am not sure which approach is better.



From rosuav at gmail.com  Wed Nov  4 22:58:33 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 14:58:33 +1100
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
 <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
Message-ID: <CAPTjJmrZer3ZZ9Y20OOT4F0g4D39MqMzSZ7nB8407N0-C=8avQ@mail.gmail.com>

On Thu, Nov 5, 2015 at 2:41 PM,  <zljubisic at gmail.com> wrote:
> Raising an exception forces me to put every call of the get_html function in try/except block.
> If I am returning a special value, than I can call get_html and then test the value.
>
> I am not sure which approach is better.

Raising an exception means that if you fail to put it in a try/except,
you get a traceback that walks you through the exact location of the
problem.

Returning a special value means that if you fail to test the value,
you either get an exception further on (if you get back None and try
to treat it as a string, for instance), or get incorrect results, with
no indication of the actual cause of the problem.

Which would you prefer?

ChrisA


From zljubisic at gmail.com  Wed Nov  4 23:11:38 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Wed, 4 Nov 2015 20:11:38 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <mailman.74.1446497962.4463.python-list@python.org>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <mailman.74.1446497962.4463.python-list@python.org>
Message-ID: <f6bec431-e37c-42f7-8b1a-77e326430578@googlegroups.com>

On Monday, 2 November 2015 21:59:45 UTC+1, Ian  wrote:


> I'm having a hard time understanding what question you're asking. 

:)
I am really having a hard time to explain the problem as English is not my first language.

> You
> have a lot of discussion about where to handle exceptions, 

That's right. I am not sure where to handle exceptions and at the same time to have the code clean as possible.

For example John from the previous post suggested raising exceptions in the get_html procedure. That would mean that I should put every call of get_html function to the try/except block.

In this particular example, I would like just to know whether I managed to get_html or not.
In case I am experiencing some problems inside of the get_html function I could maybe retry several times, but this function should return the html or inform the caller that it is unable to get the html. For caller, the reason why get_html function couldn't get the html is not important.

For now, I am thinking that maybe I should use an approach in which I will have except block in get_html that will be responsible for several exceptions, something like this:

def get_html(url):

    try:
        wpage = requests.get(url)
    except ConnectionError, exception_a, exceptionb...:
        flog('warning', 'ConnectionError exception', log_except=True)
        raise NoHtml

    return

In that way the caller can put get_html function in try/except block but just paying an attention to the NoHtml exception which is much clearer than to have except ConnectionError
except exception_a
except exceptionb...: 
in every call of the get_html.

> but the
> examples that you show are of logging the the exception and re-raising
> it, which is a good practice but distinct from handling the exception.

I mentioned logging in get_html because I don't know what else I should do with an exception in get_html function.

> Then you seem to be asking about the practice of returning None as an
> alternative to propagating the exception, but the example you show
> only returns None in a case where no exception was raised in the first
> place.

I returned None based of the wpage.status_code == requests.codes.ok.
I assume that if this condition is true, everything went well.
Otherwise, I could forget to put some explicit exceptions in the except block so try block will pass even if certain exception has happened.
I read that catching all exception with except Exception as e: is not a good option. 

> None is arguably reasonable to return when it makes sense as a
> non-exceptional value in the context. For example, if you're looking
> up a policy that may or may not exist, then your get_policy function
> might return None to indicate no value. If get_policy fails because of
> an RPC timeout however, then it needs to raise an exception rather
> than possibly incorrectly returning "no policy".

If I understood correctly, in my case I could ask for getting the html from non existent web page or I can have communication (network) problem.
In any of these two cases if I return None I will newer know that web page doesn't exist. Good point.

> In comparison, if you're returning something that should always have a
> value, then you should never return None. In such a case, None would
> indicate that something went wrong, but it lacks any information about
> *what* went wrong. An exception, on the other hand, is ideal for
> carrying that sort of information. Returning None in such a scenario
> is also risky in that the caller may not be expecting None and may try
> to treat it as a normal value. In some cases this may even appear to
> work until something breaks in a completely different part of the
> code.

So my get_html function should never return None in that case.
 
> In the example given, the case where None is returned is clearly an
> exceptional case (non-success) even though no exception was raised by
> requests.get. You should raise an exception there instead of returning
> None to allow the caller better control over the situation.

I am kind of getting the philosophy of exceptions but I still have some dilemmas as you could see above. 

Thank you very much for your comments.

Regards.


From zljubisic at gmail.com  Wed Nov  4 23:18:20 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Wed, 4 Nov 2015 20:18:20 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <mailman.43.1446695916.16136.python-list@python.org>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
 <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
 <mailman.43.1446695916.16136.python-list@python.org>
Message-ID: <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>

> Which would you prefer?

So if I am just checking for the ConnectionError in get_html and a new exception arises, I will have traceback to the get_html function showing that unhandled exception has happened.
Now I have to put additional exception block for managing the new exception in the get_html function and I am covered.

Is that what you wanted to say?


From rosuav at gmail.com  Wed Nov  4 23:51:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 15:51:41 +1100
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
 <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
 <mailman.43.1446695916.16136.python-list@python.org>
 <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>
Message-ID: <CAPTjJmpBTE_C6QFMRyK2c493x6yoY0JLX--5eqjiSsbz-q=AfQ@mail.gmail.com>

On Thu, Nov 5, 2015 at 3:18 PM,  <zljubisic at gmail.com> wrote:
>> Which would you prefer?
>
> So if I am just checking for the ConnectionError in get_html and a new exception arises, I will have traceback to the get_html function showing that unhandled exception has happened.
> Now I have to put additional exception block for managing the new exception in the get_html function and I am covered.
>
> Is that what you wanted to say?

Yep. I would definitely recommend having get_html raise an exception
on any problem; here's the structure I'd use:

def get_html(...):
    try:
        ... actually go get the info
        return info
    except (ConnectionError, OSError, SocketError) as e:
        raise ContentNotFoundError from e

This means there are three possibilities:

1) Everything works correctly, and get_html returns something useful.

2) An exception occurs of a type that you expect - the server didn't
respond, or the OS threw back a failure, or whatever. (You'd decide
what set of exceptions this represents.) In this case, you get a
single exception that wraps that up and summarizes the problem as
"Content Not Found". The original exception is retained in the
__cause__ of the ContentNotFoundError, so no information is lost.

3) An unexpected exception occurs - your script runs out of memory, or
there's a bug in your code, or anything else. The exception will
simply bubble up, and be dealt with somewhere else.

To use this code, what you'd do is:

try:
    data = get_html(...)
except ContentNotFoundError:
    # deal with the case of not having anything to work with

Omitting the try/except is a perfectly reasonable way of working, too.
Just call get_html, and if ever it can't get a result, the exception
continues to propagate. It's easy, it's straight-forward, and it's
unambiguous - any problem you don't expect becomes an exception.

ChrisA


From tian.su.yale at gmail.com  Thu Nov  5 00:02:07 2015
From: tian.su.yale at gmail.com (tian.su.yale at gmail.com)
Date: Wed, 4 Nov 2015 21:02:07 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
 <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
 <mailman.43.1446695916.16136.python-list@python.org>
 <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>
Message-ID: <7ab19923-54e9-49b8-a982-a4b2c2e9c874@googlegroups.com>

? 2015?11?4???? UTC-6??10:18:33?zlju... at gmail.com???
> > Which would you prefer?
> 
> So if I am just checking for the ConnectionError in get_html and a new exception arises, I will have traceback to the get_html function showing that unhandled exception has happened.
> Now I have to put additional exception block for managing the new exception in the get_html function and I am covered.
> 
> Is that what you wanted to say?

Hi,
If I may, I feel you are trying to address a few separate questions, although they do relate to each other.
1. Coding Design: with the try/except block inside or outside the function
2. Exception Handling: What to do with new un-anticipated exceptions
3. How to record the exception for reference: logging or special value

My feeling is:
1. Personally prefer to put try/except block outside the function, to keep the code clean and easy to follow.
2. I would suggest follow the Test Driven Development (TDD) approach. You are not able to anticipate all types of possible exceptions. However, I'm sure you have a pretty good idea about what exceptions are more likely to happen and cause you problem. In that case, just develop your code to pass these tests, and refactor it in the future if really needed. Not necessary to push your code to be perfect, able to handle every possible exception.
3. Kind of personal choice here, since no matter which way you go, you do need to follow it up and deal with them. Probably I would log it just for record keeping purpose. As long as you follow up and trace back to the root cause, they seem to serve the same goal.
Hope this helps...
All the best,
Tian


From tian.su.yale at gmail.com  Thu Nov  5 00:15:38 2015
From: tian.su.yale at gmail.com (tian.su.yale at gmail.com)
Date: Wed, 4 Nov 2015 21:15:38 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
Message-ID: <a9201732-4c33-41bf-9da4-f9dd395bd522@googlegroups.com>

Hi,
If I may, I feel you are tying to address a few questions at the same time, although they are related
1. Where to put the try/except block, inside or outside the function
2. How to deal with un-anticipated exceptions
3. How to keep record
My personal feelings are:
1. Kind of prefer try/except block outside the function though. This way it looks clean and easy to follow. In terms of logging the url, since you pass it to the function anyway, there should be ways to keep this option, even with the block written outside the function.
2. From code development perspective, would suggest you follow Test Driven Development (TDD) approach. Nobody can anticipate all of the possible outcomes, but I'm sure you have a pretty good idea about the most likely scenarios, and just make sure that your code is suitable for these scenarios. When future new exceptions arise, you can always refactor your code as needed.
3. Feel it's a personal choice here as being pointed out earlier. No mater which way you go, you just have to follow it up and deal with it, trace it back to the root cause. I kind of prefer logging, so to keep a good record for myself, and you can make it very informative.
Hope this helps.
All the best,
Tian


From tian.su.yale at gmail.com  Thu Nov  5 00:39:16 2015
From: tian.su.yale at gmail.com (tian.su.yale at gmail.com)
Date: Wed, 4 Nov 2015 21:39:16 -0800 (PST)
Subject: raw_input and break
In-Reply-To: <h%u_x.29450$bN3.2901@fx06.am1>
References: <h%u_x.29450$bN3.2901@fx06.am1>
Message-ID: <4270fade-5f09-4935-a99a-f2be344202b2@googlegroups.com>

? 2015?11?4???? UTC-6??3:45:09?input/ld... at casema.nl???
> I have an continues loop with "while True:"
> Now I want to use "raw_input" and when I press "s" on the keybord that it will 
> "break" the continues loop.
> 
> I tried:
> choices = raw_input
> if choises == s:
> break
> 
> But even when I not press "s" it "break"
> I want that I not press "s" the script continues.
> 
> Any ideas ?
> 
> Thanks
> 
> 
> 
> -- 
> --------------------------------- --- -- -
> Posted with NewsLeecher v7.0 Beta 2
> Web @ http://www.newsleecher.com/?usenet
> ------------------- ----- ---- -- -

while True:
    inp = input("Enter whatever you want, letter 's' to stop: ")
    if inp == 's':
        print("Program stopped.")
        break
    print("You just entered:", inp)

Is this along the line that you are thinking? As pointed out earlier, it will be much easier for people to help if you can share the exact code you put into and the error messages as well. Thanks and good luck!
All the best,
Tian


From rurpy at yahoo.com  Thu Nov  5 00:42:16 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 21:42:16 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.37.1446683628.16136.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
 <mailman.37.1446683628.16136.python-list@python.org>
Message-ID: <a33ce924-c795-447b-8fb9-d7e01fee8936@googlegroups.com>

On 11/04/2015 05:33 PM, Chris Angelico wrote:
> On Thu, Nov 5, 2015 at 11:13 AM, rurpy--- via Python-list
> <python-list at python.org> wrote:
>> On 11/04/2015 07:52 AM, Chris Angelico wrote:
>>> On Thu, Nov 5, 2015 at 1:38 AM, rurpy wrote:
>>>> I'm afraid you are making a category error but perhaps that's in
>>>> part because I wasn't clear.  I was not talking about computer
>>>> science.  I was talking about human beings learning about computers.
>>>> Most people I know consider programming to be a higher level activity
>>>> than "using" a computer: editing, sending email etc.  Many computer
>>>> users (not programmers) learn to use regular expressions as part
>>>> of using a computer without knowing anything about programming.
>>>> It was on that basis I called them more fundamental -- something
>>>> learned earlier which is expanded on and added to later.  But you
>>>> have a bit of a point, perhaps "fundamental" was not the best choice
>>>> of word to communicate that.
>>>
>>> The "fundamentals" of something are its most basic functions, not its
>>> most basic uses. The most common use of a computer might be to browse
>>> the web, but the fundamental functionality is arithmetic and logic.
>>
>> If one accepted that then one would have to reject the term "fundamental
>> use" as meaningless.  A quick trip to google shows that's not true.
>
> A quick trip to Google showed me that there are a number of uses of
> the phrase, mostly in scientific papers and such. I've no idea how
> that helps your argument.

I was showing that your objection to my use of "fundamental" on the 
grounds it does not apply to "use" is patently silly.  From Google:

   interferes with B's more fundamental use because
   fundamental use of english
   The fundamental use of testing
   Fundamental Use of the Michigan Terminal System
   negotiate a fundamental use and exchange of power
   the most fundamental use of pointers
   makes fundamental use of statistical theory

This is what I meant in a recent post when I referred to the Alice-
in-Wonderland nature of this group.  I'm afraid I don't have the 
time or interest to discuss basic english with you.  If you want 
to maintain that "fundamental" does apply to "use" please go right
ahead, it's your credibility at risk.

>> But string matching *is* a fundamental problem that arises frequently
>> in many aspects of CS, programming and, as I mentioned, day-to-day
>> computer use.  Saying its "only" for pattern matching is like saying
>> floating point numbers are "only" for doing non-integer arithmetic,
>> or unicode is "only" for representing text.  (Neither of those is a
>> good analogy because both lack the important theoretical underpinnings
>> that regular expressions have [*]).
>
> String matching does happen a lot. How often do you actually need
> pattern matching? Most of the time, you're doing equality checks - or
> prefix/suffix checks, at best.
>
>> There would be far fewer computer languages, and they would be much
>> more primitive if regular expressions (and the fundamental concepts
>> that they express) did not exist.
>
> So? There would also be far fewer computer languages if braces didn't
> exist, because we wouldn't have the interminable arguments about
> whether they're good or not.

Sorry, that makes no sense to me.  

>> To be sure, I did gloss over Michael Torries' point that there are
>> other concepts that are more basic in the context of learning
>> programming, he was correct about that.
>>
>> But that does not negate the fact that regexes are important and
>> fundamental.  They are both very useful in a practical sense (they
>> are even available in Microsoft Excel) and important in a theoretical
>> sense.  You are not well rounded as a programmer if you decline to
>> learn about regular expressions because "they are too cryptic", or
>> "I can do in code anything they do".
>
> You've proven that they are important, but in no way have you proven
> them fundamental. A regular expression library is the ideal solution
> to the problem "I want to let my users search for patterns of their
> own choosing". That's great, but it's only one specific class of
> problem.

If you think that is the sole use of pattern matching or even the most
important use, I can understand why you find regexes fairly useless.
Lexing (tokenization) and simple parsing are often done with regular
expressions.  Many dozens of times a year I write programs to extract 
or munge data in text files.  Three days ago I had to extract data from 
a 500MB log file for insertion in a database that used many regexes,
even some that could have been replaced by python methods.  But mixing
the two approaches would have been less clear than using regexs 
consistently.

Text recognition and modification is an *extremely* common need, not
some niche application as you suggest.

>> I think the constant negative reception the posters receive here when
>> they ask about regexes does them a great disservice.
>>
>> By all means point out that python offers a number of functions that
>> can avoid the need for using regexes in simple cases.  Even point out
>> that you (the plural you) don't like them and prefer other solutions
>> (like writing code that does the same thing in a more half-assed bug
>> ridden way, the posts in this thread being a case in point.)
>>
>> But I really wish every mention of regexes here wasn't reflexively
>> greeted with a barrage of negative comments and that lame "two problems"
>> quote, especially without an answer to the poster's regex question.
>
> When has that happened? Usually there'll be at least two answers - one
> that uses a regex and one that doesn't - and people get to read both.

No, usually there is one answer with a regex, five advising against 
regexes, and two with the silly "two problems" quote.  The impression
one is left with is that regexs are bad and to be avoided.  

Rarely to never does one see a response encouraging a poster 
to learn about and use regular expressions which is why I spoke
up this time.

>>> Sure, you can
>>> abuse that into a primality check and other forms of crazy arithmetic,
>>> but it's not what they truly do. I also would not teach regexes to
>>> people as part of an "introduction to computing" course, any more than
>>> I would teach the use of Microsoft Excel, which some such courses have
>>> been known to do. (And no, it's not because of the Microsoftness. I
>>> wouldn't teach LibreOffice Calc either.) You don't need to know how to
>>> work a spreadsheet as part of the basics of computer usage, and you
>>> definitely don't need an advanced form of text search.
>>
>> Seems to me that clearly depends on the intent of the class, the students
>> goal's, what they'll be studying after the class, what their current
>> level of knowledge is, etc.  Your scenario seems way too under-specified
>> to say anything definitive.  And further, the pedagogy of CS (or of any
>> subject of education) is not "settled science" and that kind of question
>> almost never has a clear right/wrong answer.
>
> Uhh, "introduction to computing". What's the current level of
> knowledge? Close to zero. That's the whole point of an introductory
> class. It's a place where you teach the basics.

"Introduction to computing" covers everything from teaching unemployed 
people how to use word and excel to a first "algorithms and data structures"
for AP high-school kids to programming with a heavy dose of hardware
architecture.  What "the basics" are is, as far as I know, still the 
subject of debate and research among professional educators.

>> This list is not a class.  If someone comes here with a question about
>> Python's regexes they deserve an answer and not be bombarded with reasons
>> why they shouldn't be using regexes beyond mentioning some of the alternatives
>> in a "oh, by the way" way.  (And yes, I recognize in this case the OP did
>> get a good answer from MRAB early on.)
>
> "I want to swim from Sydney to Los Angeles, but my gloves keep wearing
> out half way across the Pacific. How can I make my gloves strong
> enough to get me to LA?"
>
> Response 1: "If you use industrial-strength gloves and go via Papua
> New Guinea, you can double up the gloves and swim to LA."
>
> Response 2: "Swimming across the Pacific is a bad idea. Have you
> considered taking a boat or plane instead?"
>
> Which is the more helpful response? You can go ahead and assume the OP
> always knows best; I'm going to at least offer some alternatives.

Using a regular expression (even when there are other alternatives)
is not analogous to "Swimming across the Pacific".  (Back in Wonderland
again.)  Using a regex is *not* a life threatening situation.

I've said repeatedly that pointing out alternatives is fine.  Pointing 
out there is no need for a regex when searching for a constant string
is fine.  And similar...  But the responses here often go well beyond 
that in negativity.

My own theory is that regexes are associated with Perl in the minds 
of many participants here and thus provoke an automatic immune 
reaction.


From rurpy at yahoo.com  Thu Nov  5 00:54:29 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 21:54:29 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <563abe6f$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
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 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
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Message-ID: <8d2e4d8d-dead-4ffd-b6fd-00d16cd0c26c@googlegroups.com>

On Wednesday, November 4, 2015 at 7:31:34 PM UTC-7, Steven D'Aprano wrote:
> On Thu, 5 Nov 2015 11:13 am, rurpy wrote:
> 
> > There would be far fewer computer languages, and they would be much
> > more primitive if regular expressions (and the fundamental concepts
> > that they express) did not exist.
> 
> Well, that's certainly true. But only because contra-factual statements can
> imply the truth of anything. If squares had seven sides, then Joseph Stalin
> would have been the first woman to go to the moon on horseback.

Yes, thank you for that profoundly insightful comment.


From rurpy at yahoo.com  Thu Nov  5 00:59:51 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 21:59:51 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
 <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>

On 11/04/2015 07:24 PM, Steven D'Aprano wrote:
> On Thu, 5 Nov 2015 11:24 am, wrote:
>
>> You will find they are an indispensable tool, not just in Python
>> programming but in many aspects of computer use.
>
> You will find them a useful tool, but not indispensable by any means.
>
> Hint:
>
> - How many languages make arithmetic a built-in part of the language? Almost
> all of them. I don't know of any language that doesn't let you express
> something like "1 + 1" using built-in functions or syntax. Arithmetic is
> much closer to indispensable.

By my count there are 2377.  That's counting rpn languages where it is
1 1 +.  If you don't count them it is 2250.

> - How many languages make regular expressions a built-in part of the
> language? Almost none of them. There's Perl, obviously, and its
> predecessors sed and awk, and probably a few others, but most languages
> relegate regular expressions to a library.

Yes, like python relegates io to a library.  
Clearly useful but not indispensable, after all who *really* needs 
anything beyond print() and input().  And that stuff in math like sin()
and exp().  How many programs use that geeky trig stuff?  Definitely not 
indispensable.  In fact, now that you pointed it out to me, clearly all
that stdlib stuff is dispensable, all one really needs to write 
"real programmer" programs is just core python.  Who the hell needs "sys"!

> - How many useful programs can be written with regexes? Clearly there are
> many. Some of them would even be quite difficult without regexes. (In
> effect, you would have to invent your own pattern-matching code.)

Lucky for me then that there are regexes.

> - How many useful programs can be written without regexes? Clearly there are
> also many. Every time you write a Python program and fail to import re,
> you've written one.

By golly, you're right.  Not every program I write uses regexes.
Who would have thought?!  However, you failed to establish that 
the programs I write without re are useful.

> Can you call yourself a well-rounded programmer without at least a basic
> understanding of some regex library? Well, probably not. But that's part of
> the problem with regexes. They have, to some degree, driven out potentially
> better -- or at least differently bad -- pattern matching solutions, such
> as (E)BNF grammars, SNOBOL pattern matching, or lowly globbing patterns. Or
> even alternative idioms, like Hypercard's "chunking" idioms.

Hmm, very good point.  I wonder why all those "potentially better" 
solutions have not been more widely adopted?  A conspiracy by a 
secret regex cabal? 

> When all you have is a hammer, everything looks like a nail.

Lucky for us then, that we have more than just hammers!

Sorry for the flippant response (well, not really) but I find your 
arguments pedantic beyond the point of absurdity.  For me, regular 
expressions are indispensable in that if they were not available in 
Python I would not use Python.  The same is true of a number of other 
stdlib modules.  I don't give a rat's ass whether they are in a 
"library" that has to be explicitly requested with import or a 
"library" that is automatically loaded at startup.


From rurpy at yahoo.com  Thu Nov  5 01:27:46 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Wed, 4 Nov 2015 22:27:46 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <mailman.39.1446691567.16136.python-list@python.org>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
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Message-ID: <7ffc8ea8-6445-4c59-b3b6-611edfbf4f62@googlegroups.com>

On Wednesday, November 4, 2015 at 7:46:24 PM UTC-7, Chris Angelico wrote:
> On Thu, Nov 5, 2015 at 11:24 AM, rurpy wrote:

> The "take away" that I recommend is: Rurpy loves to argue in favour of
> regular expressions,

No, I don't love it, I quite dislike it.

> but as you can see from the other posts, there
> are alternatives, which are often FAR superior.

No, not FAR superior, just preferable and just in the simple cases,
regexes generally being better in anything beyond simple. 


From greg.ewing at canterbury.ac.nz  Thu Nov  5 01:39:10 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Thu, 05 Nov 2015 19:39:10 +1300
Subject: Detection of a specific sound
In-Reply-To: <mailman.36.1446569757.8789.python-list@python.org>
References: <CAPfdVgF1erUtxgKGm9eky_q8X24L88PkFEWyTL4hqUNUvGvrzQ@mail.gmail.com>
 <E7CB9062-12AC-4C3D-B3C8-D80B90BB1C56@mac.com>
 <CALwzidkZnERs6ccmZyeurdCCRF_b61+62S0dfYFuH2Cp8x++GA@mail.gmail.com>
 <mailman.36.1446569757.8789.python-list@python.org>
Message-ID: <da0bsgFr0jpU1@mid.individual.net>

Joel Goldstick wrote:
> Sometimes (maybe most times) the follow on discussion goes off on
> insightful tangents that may have little to do with the OP.

And then someone mentions a Monty Python sketch about
Hitler, thereby both bring the discussion back on-topic
*and* invoking Godwin's Law at the same time.

Don't-mention-the-war-ly,
Greg


From auriocus at gmx.de  Thu Nov  5 02:32:21 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 5 Nov 2015 08:32:21 +0100
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <mailman.38.1446684164.16136.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
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 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
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 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
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Message-ID: <n1f0hv$g3n$1@dont-email.me>

Am 05.11.15 um 01:42 schrieb Chris Angelico:
> On Thu, Nov 5, 2015 at 6:38 AM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> As someone who grew up on MS-DOS, I'd like to mention that EDLIN's
> value wasn't in the obvious places. There were two features it had
> that most other editors didn't: firstly, it would read only as much of
> the file as it needed, so you could edit a file larger than available
> memory; and secondly, all commands came from stdin, which could be
> redirected - making it a poor man's 'sed'. Using EDLIN for regular
> file editing was never the normal thing.

I also grew up with MSDOS, albeit some later version (3.0 was the first, 
I think I remember). I knew that EDLIN existed, but never ever have used 
it. On my first "own" (actually my father's) machine, the Amstrad 
PC1512, there was a preinstalled GUI working environment called GEM from 
Digital Research. The DOS commandline was used for configuring and 
booting the system, but never for editing files. I had used copy con: to 
create a file. If I'm not mistaken, DR shipped some "visual" editor for 
DOS with it as an addition.

The point I'm so amused is, that MS has not felt the need to ship a real 
editor, and also cut back on most of the other tools that make 
computing, even on commandlines, a pleasant experience. Readline? 
Tab-Completion? I read a magazine called "DOS", where they scripted the 
hell out of .BAT-files. When they first showed an article about bash 
programming, I was really jealous that the people on these strange, 
exotic OSes had such a complete programming language at their disposal. 
Now I can't imagine giving it back ever.

>
> Fast forward a decade or two, and I'm working on a MUD server for a
> friend. It incorporates an editor that can be used on a dumb telnet
> connection - and it's line based again. So there's clearly some value
> here :) Visual editors get the lion's share of actual editing work,
> but in special circumstances, it is nice to have a quick little
> ed-like program around.

In this case I'd copy the file to the local machine and sync it using 
rsync or git. It's almost as terse in terms of bandwidth as the manual 
editing commands, but a lot more comfortable.

	Christian


From vmt.eiz at gmail.com  Thu Nov  5 02:36:01 2015
From: vmt.eiz at gmail.com (Akshat Tripathi)
Date: Wed, 4 Nov 2015 23:36:01 -0800 (PST)
Subject: Unable to make http request to django server using
 twisted.web.client.AGENT
Message-ID: <ac674dfd-7da1-4f47-8a13-ba3c4128d89b@googlegroups.com>

I have written a basic tcp server factory, server client and a service using twisted. The tcp server acts as the middleware between a django server and an another program (let's call it client program).

What I want to achieve -

1.client requests the middleware tcp server;

2.it sends a string as the request body;

3.the middleware tcp server deserializes information from the request.

4.middleware furthers the serialized information to the django server.

5.The django server then responds to the middleware server which furthers the response to the client after serializing the response.

I am able to reach till step 3, but am unable to make any http request to the django server.




The following is my middleware.py

from twisted.internet.protocol import ServerFactory
from twisted.internet.protocol import Protocol

from test_service import MyService


class TCPServerProtocol(Protocol):
    data = ''

    def connectionMade(self):
        self.deferred = self.factory.service.deferred
        self.deferred.addCallback(self.factory.service.s)
        self.deferred.addCallback(self.transport.write)
        self.deferred.addBoth(lambda r: self.transport.loseConnection)

    def dataReceived(self, data):
        self.data += data

    def connectionLost(self, reason):
        self.forward(self.data)

    def forward(self, data):
        if self.deferred is not None:
            d, self.deferred = self.deferred, None
            d.callback(data)

class TCPServerFactory(ServerFactory):

    protocol = TCPServerProtocol

    def __init__(self, service):
        self.service = service

def runserver(ip, port):
    iface =  {'home': '192.168.0.104', 'work': '127.0.0.1'}
    service = MyService()
    factory = TCPServerFactory(service)
    from twisted.internet import reactor
    reactor.listenTCP(port=port, factory=factory, interface=iface[ip])
    reactor.run()

if __name__ == '__main__':
    import sys
    ip = sys.argv[1]
    port = int(sys.argv[2])
    runserver(ip, port)




The following is test_service.py

from twisted.internet.defer import Deferred

from test_http_client import HTTPClientFactory

class MyService(object):
    def __init__(self):
        self.deferred = Deferred()

    def s(self, data):
        kwargs = {}
        kwargs['url'] = b'http://127.0.0.1:8000/some/end/point'
        kwargs['url'] = kwargs['url'].encode('latin-1')
        kwargs['method'] = 'POST'
        kwargs['data'] = data

        client = HTTPClientFactory(**kwargs)
        d = client.deferred
        return d


The following is test_http_client.py

from StringIO import StringIO
import json

from twisted.internet.protocol import Protocol
from twisted.internet.defer import Deferred
from twisted.web.client import Agent, FileBodyProducer
from twisted.web.http_headers import Headers


class HTTPClientProtocol(Protocol):
    def __init__(self, finished):
        self.finished = finished
        self.data = ''

    def dataReceived(self, data):
        print '----------Data Received by HTTPClientProtocol----------'
        print data
        self.data += data

    def connectionLost(self, reason):
        print '----------HTTP Client connection Lost----------'
        print reason.getErrorMessage()
        if self.finished is not None:
            print 'finished is not None'
            f, self.finished = self.finished, None
            f.callback(self.data)

class HTTPClientFactory(object):

    """
    Class handling communication with HTTP server.
    """

    def __init__(self, **kwargs):
        data = kwargs['data'] 
        try:
            body = FileBodyProducer(StringIO(json.dumps(data)))
            print '----------Request body object created----------'
        except Exception as e:
            print '----------Request body object creation FAILURE----------'
            print e
            return e  
        url = kwargs.get('url', None)
        method = kwargs.get('method', None)

        from twisted.internet import reactor
        agent = Agent(reactor)
        if not data:
            body = None

        self.deferred = agent.request(method,
                                    url,
                                    Headers({'Content-Type': ['application/json']}),
                                    bodyProducer=body)

        self.deferred.addCallback(self.get_response)

    def get_response(self, response):
        print 'Response received'
        finished = Deferred()
        response.deliverBody(HTTPClientProtocol(finished))
        return finished


From greg.ewing at canterbury.ac.nz  Thu Nov  5 02:55:54 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Thu, 05 Nov 2015 20:55:54 +1300
Subject: Regular expressions
In-Reply-To: <mailman.21.1446652375.16136.python-list@python.org>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.21.1446652375.16136.python-list@python.org>
Message-ID: <da0gcbFs13sU1@mid.individual.net>

Tim Chase wrote:

> You get even crazier when you start adding zgrep/zegrep/zfgrep.

It's fitting somehow that we should need an RE
to describe all the possible names of the grep
command.

-- 
Greg


From rosuav at gmail.com  Thu Nov  5 03:00:13 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 19:00:13 +1100
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <n1f0hv$g3n$1@dont-email.me>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <mailman.38.1446684164.16136.python-list@python.org>
 <n1f0hv$g3n$1@dont-email.me>
Message-ID: <CAPTjJmoCmFK9CsEXt=PdbfJCTogDoc3Q4FQuDoaDmmj1-4vJ4Q@mail.gmail.com>

On Thu, Nov 5, 2015 at 6:32 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> The point I'm so amused is, that MS has not felt the need to ship a real
> editor, and also cut back on most of the other tools that make computing,
> even on commandlines, a pleasant experience. Readline? Tab-Completion? I
> read a magazine called "DOS", where they scripted the hell out of
> .BAT-files. When they first showed an article about bash programming, I was
> really jealous that the people on these strange, exotic OSes had such a
> complete programming language at their disposal. Now I can't imagine giving
> it back ever.

I don't remember whether DOS 3.x had it, but we upgraded to MS-DOS 5.0
fairly early in my life, and that's most of what I remember. In that
version, we had a thing called DOSKey, which gave you command history
and some editing keys (not nearly as rich as readline, of course, but
good enough for a lot of work); tab completion was an astonishing new
feature when I first met a bash-derived shell. And yes, astonishing.
I'd thought that GUIs had this advantage over command lines in that
long file names (especially with spaces and such) didn't cost you
anything, since you simply click to select; I somewhat resented them
for it. And then, wow, tab completion! You type the beginning of the
name and it fills in the rest!

>> Fast forward a decade or two, and I'm working on a MUD server for a
>> friend. It incorporates an editor that can be used on a dumb telnet
>> connection - and it's line based again. So there's clearly some value
>> here :) Visual editors get the lion's share of actual editing work,
>> but in special circumstances, it is nice to have a quick little
>> ed-like program around.
>
> In this case I'd copy the file to the local machine and sync it using rsync
> or git. It's almost as terse in terms of bandwidth as the manual editing
> commands, but a lot more comfortable.

That server didn't allow rsync/git; I think they didn't use git, and
rsync probably would have meant setting up duplicate Unix accounts for
everyone that paralleled the permissions they had on the MUD itself.
On my own server, I don't have any fine-grained permissions (either
you're allowed to edit files, or you're not), so I have a much simpler
system: you type "edit some_file_name" and it sends you the contents
of the file in a way that makes the client pop up an editor. Hit Save
in the editor, and it sends the file back. Pretty easy. But still,
there _are_ good uses for a line-based editor, even if they are rare.

ChrisA


From rosuav at gmail.com  Thu Nov  5 03:06:21 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 5 Nov 2015 19:06:21 +1100
Subject: Regular expressions
In-Reply-To: <da0gcbFs13sU1@mid.individual.net>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.21.1446652375.16136.python-list@python.org>
 <da0gcbFs13sU1@mid.individual.net>
Message-ID: <CAPTjJmrd_m-Wu2jL47_1GQWTwiEYXBy0NBU0QBXzVbY81LXrvA@mail.gmail.com>

On Thu, Nov 5, 2015 at 6:55 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Tim Chase wrote:
>
>> You get even crazier when you start adding zgrep/zegrep/zfgrep.
>
>
> It's fitting somehow that we should need an RE
> to describe all the possible names of the grep
> command.

Regex engine golf: Find the shortest regex that matches the names of
all GNU commands which accept regular expressions, and no other
commands!

ChrisA


From auriocus at gmx.de  Thu Nov  5 03:18:58 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 5 Nov 2015 09:18:58 +0100
Subject: Regular expressions
In-Reply-To: <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
 <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>
Message-ID: <n1f39d$o44$1@dont-email.me>

Am 05.11.15 um 06:59 schrieb rurpy at yahoo.com:
>> Can you call yourself a well-rounded programmer without at least a basic
>> understanding of some regex library? Well, probably not. But that's part of
>> the problem with regexes. They have, to some degree, driven out potentially
>> better -- or at least differently bad -- pattern matching solutions, such
>> as (E)BNF grammars, SNOBOL pattern matching, or lowly globbing patterns. Or
>> even alternative idioms, like Hypercard's "chunking" idioms.
>
> Hmm, very good point.  I wonder why all those "potentially better"
> solutions have not been more widely adopted?  A conspiracy by a
> secret regex cabal?

I'm mostly on the pro-side of the regex discussion, but this IS a valid 
point. regexes are not always a good way to express a pattern, even if 
the pattern is regular. The point is, that you can't build them up 
easily piece-by-piece. Say, you want a regex like "first an 
international phone number, then a name, then a second phone number" - 
you will have to *repeat* the pattern for phone number twice. In more 
complex cases this can become a nightmare, like the monster that was 
mentioned before to validate an email.

A better alternative, then, is PEG for example. You can easily write

pattern <- phone_number name phone_number
phone_number <- '+' [0-9]+ ( '-' [0-9]+ )*
name <-  [[:alpha:]]+

or something similar using a PEG parser. It has almost the same 
quantifiers as a Regex, is much more readable, runs in linear time over 
all inputs and can parse languages with the approximately the same 
complexity as the Knuth style parsers (LR(k) etc.), but without 
ambiguity. I'm really astonished that PEG parsing is not better 
supported in the world of computing, instead most people choose to stick 
to the lexer+scanner combination

Finally, an anecdote from my "early" life of computing. In 1990, when I 
was 12 years old, I participated in an annual competition of computer 
science for high school students. I was learning how to program without 
formal training, and solved one problem where a grammar was depicted as 
a flowchart and the task was to write parser for it, to check the 
validity of input strings. The grammar is depicted here (problem 1):

http://www.auriocus.de/StringKurs/RegEx/uebungen1.pdf

As a 12 year old, not knowing anything about pattern recognition, but 
thinking I was the king, as is usual for boys in that age, I sat down 
and manually constructed a recursive descent parser in a BASIC like 
language. It had 1000 lines and took me a few weeks to get it correct. 
Finally the solution was accepted as working, but my participation was 
rejected because the solutions lacked documentation. 16 years later I 
used the problem for a course on string processing (that's what the PDF 
is for), and asked the students to solve it using regexes. My own 
solution consists of 67 characters, and it took me5 minutes to write it 
down.

Admittedly, this problem is constructed, but solving similar tasks by 
regexes is still something that I need to do on a daily basis, when I 
get data from other scientists in odd formats and I need to preprocess 
them. I know people who use a spreadsheet and copy/paste millions of 
datapoints manually becasue they lack the knowledge of using such tools.

	Christian



From __peter__ at web.de  Thu Nov  5 03:33:39 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 09:33:39 +0100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1f494$afl$1@ger.gmane.org>

Steven D'Aprano wrote:

> On Wed, 4 Nov 2015 07:57 pm, Peter Otten wrote:
> 
>> I tried Tim's example
>> 
>> $ seq 5 | grep '1*'
>> 1
>> 2
>> 3
>> 4
>> 5
>> $
> 
> I don't understand this. What on earth is grep matching? How does "4"
> match "1*"?

Look for zero or more "1". Written in Python:

for line in sys.stdin:
    if re.compile("1*").search(line):
        print(line, end="")
 
>> which surprised me because I remembered that there usually weren't any
>> matching lines when I invoked grep instead of egrep by mistake. So I
>> tried another one
>> 
>> $ seq 5 | grep '[1-3]+'
>> $
>> 
>> and then headed for the man page. Apparently there is a subset called
>> "basic regular expressions":
>> 
>> """
>>   Basic vs Extended Regular Expressions
>>        In basic regular expressions the meta-characters ?, +, {, |, (,
>>        and ) lose their special meaning; instead use  the  backslashed
>>        versions \?, \+, \{, \|, \(, and \).
>> """
> 
> None of this appears relevant, as the metacharacter * is not listed. 

That's the very point. 

> So what's going on?

Most special characters are not working with grep, but * is. The quote 
explains why many regular expressions like "[1-3]+" that you may know from 
Python's re don't work, but a small subset including the ominous "1*" do.



From antoon.pardon at rece.vub.ac.be  Thu Nov  5 04:14:19 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 05 Nov 2015 10:14:19 +0100
Subject: Regular expressions
In-Reply-To: <CAPTjJmq5A-5fvyCsoZGgWjcGdTG8dAPg3_tCeTxQGnPxnhxtjg@mail.gmail.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <89a2a4a7-f483-4e94-9f68-ba77ce4b7598@googlegroups.com>
 <mailman.18.1446648732.16136.python-list@python.org>
 <74351250-2c5b-439d-abc9-65e3480cd930@googlegroups.com>
 <CAPTjJmq5A-5fvyCsoZGgWjcGdTG8dAPg3_tCeTxQGnPxnhxtjg@mail.gmail.com>
Message-ID: <563B1DEB.5000704@rece.vub.ac.be>

Op 05-11-15 om 01:33 schreef Chris Angelico:
> "I want to swim from Sydney to Los Angeles, but my gloves keep wearing
> out half way across the Pacific. How can I make my gloves strong
> enough to get me to LA?"
>
> Response 1: "If you use industrial-strength gloves and go via Papua
> New Guinea, you can double up the gloves and swim to LA."
>
> Response 2: "Swimming across the Pacific is a bad idea. Have you
> considered taking a boat or plane instead?"
>
> Which is the more helpful response? You can go ahead and assume the OP
> always knows best; I'm going to at least offer some alternatives.

What I see often enough doesn't look like offering an alternative but
more like strong argumentation against the direction the OP is going.

I have nothing against offering an alternative. There is the possibilty
that there are better methods to solve the original problem and there
is nothing wrong with suggesting this possibility.

But there is also the possibility that the direction the OP is heading
is the correct one, even if you can't see it. Take the original question
on how to recognize a line that ends with a '*' with a regular expression.

What almost noone seems to have considered is that the real problem might
have been more involved and an excellent example of a problem you can
solve with regular expressions but that there was this subproblem of recognizing
a '*' at the end of the line that was troublesome for the OP.

This is a possibility that is all too often ignored by the members on this
list. We advise people here to just show to most bare code that still 
shows the problem, yet we ignore that this effects the part of the problem we
get to see and often enough people then insist on a better alternative
to deal with the problem totally ignoring that this better alternative
may be totally useless in the original context.

-- 
Antoon Pardon



From input/ldompeling at casema.nl  Thu Nov  5 04:22:14 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Thu, 05 Nov 2015 09:22:14 GMT
Subject: raw_input and break
References: <4270fade-5f09-4935-a99a-f2be344202b2@googlegroups.com>
Message-ID: <adF_x.29624$Xj7.21693@fe35.am1>

In reply to "tian.su.yale at gmail.com" who wrote the following:

> =E5=9C=A8 2015=E5=B9=B411=E6=9C=884=E6=97=A5=E6=98=9F=E6=9C=9F=E4=B8=89 UTC=
> -6=E4=B8=8B=E5=8D=883:45:09=EF=BC=8Cinput/ld... at casema.nl=E5=86=99=E9=81=93=
> =EF=BC=9A
> > I have an continues loop with "while True:"
> > Now I want to use "raw_input" and when I press "s" on the keybord that it=
>  will=20
> > "break" the continues loop.
In this script it always break even when I not  press 's'
I want that this script go's to if mindist > us_dist(15):
And when I press 's' its stop.

Any ideas ?

--------------------------------------------------------


while True:
    enable_servo()
    servo(90)
    mindist = 80
    choices = input("letter s to stop:")
    if choices == 's':
        print ("stop")
        break
if mindist > us_dist(15):
    bwd()
    print ("backward 1x")

    














> > =20
> > I tried:
> > choices =3D raw_input
> > if choises =3D=3D s:
> > break
> > =20
> > But even when I not press "s" it "break"
> > I want that I not press "s" the script continues.
> > =20
> > Any ideas ?
> > =20
> > Thanks
> > =20
> > =20
> > =20
> > --=20
> > --------------------------------- --- -- -
> > Posted with NewsLeecher v7.0 Beta 2
> > Web @ http://www.newsleecher.com/?usenet
> > ------------------- ----- ---- -- -
> 
> while True:
>     inp =3D input("Enter whatever you want, letter 's' to stop: ")
>     if inp =3D=3D 's':
>         print("Program stopped.")
>         break
>     print("You just entered:", inp)
> 
> Is this along the line that you are thinking? As pointed out earlier, it wi=
> ll be much easier for people to help if you can share the exact code you pu=
> t into and the error messages as well. Thanks and good luck!
> All the best,
> Tian




-- 
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Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From __peter__ at web.de  Thu Nov  5 05:01:45 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 11:01:45 +0100
Subject: raw_input and break
References: <4270fade-5f09-4935-a99a-f2be344202b2@googlegroups.com>
 <adF_x.29624$Xj7.21693@fe35.am1>
Message-ID: <n1f9e9$q86$1@ger.gmane.org>

input/ldompeling at casema.nl wrote:

> while True:
>     enable_servo()
>     servo(90)
>     mindist = 80
>     choices = input("letter s to stop:")
>     if choices == 's':
>         print ("stop")
>         break
> if mindist > us_dist(15):
>     bwd()
>     print ("backward 1x")

> In this script it always break even when I not  press 's'
> I want that this script go's to if mindist > us_dist(15):
> And when I press 's' its stop.
> 
> Any ideas ?

Does it print something like

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 0
    
    ^
SyntaxError: unexpected EOF while parsing

when it stops? This is called a "traceback" and you should always include it 
in your post when you need help with an error in your script.

In this particular case the problem is that you are using Python 2 where 
input() tries to execute the text the user enters as Python code.

Tian's example code assumes Python 3.

To fix your problem replace the line

    choices = input("letter s to stop:")

in your script with

    choices = raw_input("letter s to stop:")




From input/ldompeling at casema.nl  Thu Nov  5 05:40:23 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Thu, 05 Nov 2015 10:40:23 GMT
Subject: raw_input and break
References: <mailman.50.1446717724.16136.python-list@python.org>
Message-ID: <rmG_x.48746$kZ5.30605@fe42.am1>

In reply to "Peter Otten" who wrote the following:

> input/ldompeling at casema.nl wrote:
> 
> > while True:
> >     enable_servo()
> >     servo(90)
> >     mindist = 80
> >     choices = input("letter s to stop:")
> >     if choices == 's':
> >         print ("stop")
> >         break
> > if mindist > us_dist(15):
>In this particular case the problem is that you are using Python 2 where
>input() tries to execute the text the user enters as Python code.

>Tian's example code assumes Python 3.

>To fix your problem replace the line

 >   choices = input("letter s to stop:")

>in your script with

 >   choices = raw_input("letter s to stop:")

Oh no, this is not what I want. Now it is waiting for input when its go further with the script.
Because I have an while True: so I want that the script go's continue only when I press a key then it must stop the script.

Thanks
--------------------------------------------------------------------------------------------------------------------------















> >     bwd()
> >     print ("backward 1x")
> 
> > In this script it always break even when I not  press 's'
> > I want that this script go's to if mindist > us_dist(15):
> > And when I press 's' its stop.
> > 
> > Any ideas ?
> 
> Does it print something like
> 
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "<string>", line 0
> 
>     ^
> SyntaxError: unexpected EOF while parsing
> 
> when it stops? This is called a "traceback" and you should always include it
> in your post when you need help with an error in your script.
> 
> In this particular case the problem is that you are using Python 2 where
> input() tries to execute the text the user enters as Python code.
> 
> Tian's example code assumes Python 3.
> 
> To fix your problem replace the line
> 
>     choices = input("letter s to stop:")
> 
> in your script with
> 
>     choices = raw_input("letter s to stop:")




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From __peter__ at web.de  Thu Nov  5 06:38:05 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 12:38:05 +0100
Subject: raw_input and break
References: <mailman.50.1446717724.16136.python-list@python.org>
 <rmG_x.48746$kZ5.30605@fe42.am1>
Message-ID: <n1ff2v$sim$1@ger.gmane.org>

input/ldompeling at casema.nl wrote:

>  >   choices = raw_input("letter s to stop:")
> 
> Oh no, this is not what I want. Now it is waiting for input when its go
> further with the script. Because I have an while True: so I want that the
> script go's continue only when I press a key then it must stop the script.

Solutions to that problem are OS-dependent. For Unix terminals

https://docs.python.org/2/faq/library.html#how-do-i-get-a-single-keypress-at-a-time

shows one way which I used to write the contextmanager below:

$ cat capture_key.py
import termios, fcntl, sys, os

from contextlib import contextmanager


@contextmanager
def nonblocking(stdin=None):
    if stdin is None:
        stdin = sys.stdin

    fd = sys.stdin.fileno()

    oldterm = termios.tcgetattr(fd)
    newattr = termios.tcgetattr(fd)
    newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
    termios.tcsetattr(fd, termios.TCSANOW, newattr)

    oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, oldflags | os.O_NONBLOCK)
    def read(n):
        try:
            return stdin.read(n)
        except IOError:
            return ""
    try:
        yield read
    finally:
        termios.tcsetattr(fd, termios.TCSAFLUSH, oldterm)
        fcntl.fcntl(fd, fcntl.F_SETFL, oldflags)


Put the capture_key.py module into the same folder as your script and use it 
like in the demo below:

from capture_key import nonblocking

# put your code here

with nonblocking() as read:
    print("letter s to stop:")
    while True:
        enable_servo()
        servo(90)
        mindist = 80
        choices = read(1)
        if choices == 's':
            print("stop")
            break
if mindist > us_dist(15):
    bwd()
    print("backward 1x")




From steve at pearwood.info  Thu Nov  5 07:05:12 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 05 Nov 2015 23:05:12 +1100
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.48.1446712433.16136.python-list@python.org>
Message-ID: <563b45fa$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Thu, 5 Nov 2015 07:33 pm, Peter Otten wrote:

> Steven D'Aprano wrote:
> 
>> On Wed, 4 Nov 2015 07:57 pm, Peter Otten wrote:
>> 
>>> I tried Tim's example
>>> 
>>> $ seq 5 | grep '1*'
>>> 1
>>> 2
>>> 3
>>> 4
>>> 5
>>> $
>> 
>> I don't understand this. What on earth is grep matching? How does "4"
>> match "1*"?
> 
> Look for zero or more "1".

Doh!

Oh the shame, I knew that. Somehow I tangled myself in a knot, thinking that
it had to be 1 *followed by* zero or more characters. But of course it's
not a glob, it's a regex.




-- 
Steven



From input/ldompeling at casema.nl  Thu Nov  5 07:59:40 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Thu, 05 Nov 2015 12:59:40 GMT
Subject: raw_input and break
References: <mailman.51.1446723514.16136.python-list@python.org>
Message-ID: <0pI_x.14172$aq1.6942@fe58.am1>

In reply to "Peter Otten" who wrote the following:

> input/ldompeling at casema.nl wrote:
> 
> > >   choices = raw_input("letter s to stop:")
> > 
> > Oh no, this is not what I want. Now it is waiting for input when its go
> > further with the script. Because I have an while True: so I want that the
> > script go's continue only when I press a key then it must stop the script.
> 
> Solutions to that problem are OS-dependent. For Unix terminals
> 
> https://docs.python.org/2/faq/
> library.html#how-do-i-get-a-single-keypress-at-a-time
> 
> shows one way which I used to write the contextmanager below:
> 
> $ cat capture_key.py
> import termios, fcntl, sys, os
> 
> from contextlib import contextmanager
> 
> 
> @contextmanager
> def nonblocking(stdin=None):
>     if stdin is None:
>         stdin = sys.stdin
> 
>     fd = sys.stdin.fileno()
> 
>     oldterm = termios.tcgetattr(fd)
>     newattr = termios.tcgetattr(fd)
>     newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
>     termios.tcsetattr(fd, termios.TCSANOW, newattr)
> 
>     oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
Thanks for the reply. Is there no easy way to do so in python ?
I am using the raspberry pi with Wheezy and for the robot the GoPiGo which is connected on the raspberry pi.
The GoPiGo board has his own code like: fwd()="forward" bwd()="backward" right()="right" left="left" and so on.
I am just a dummie with python.

Thanks
----------------------------------------------------------

>     fcntl.fcntl(fd, fcntl.F_SETFL, oldflags | os.O_NONBLOCK)
>     def read(n):
>         try:
>             return stdin.read(n)
>         except IOError:
>             return ""
>     try:
>         yield read
>     finally:
>         termios.tcsetattr(fd, termios.TCSAFLUSH, oldterm)
>         fcntl.fcntl(fd, fcntl.F_SETFL, oldflags)
> 
> 
> Put the capture_key.py module into the same folder as your script and use it
> like in the demo below:
> 
> from capture_key import nonblocking
> 
> # put your code here
> 
> with nonblocking() as read:
>     print("letter s to stop:")
>     while True:
>         enable_servo()
>         servo(90)
>         mindist = 80
>         choices = read(1)
>         if choices == 's':
>             print("stop")
>             break
> if mindist > us_dist(15):
>     bwd()
>     print("backward 1x")




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From albert at spenarnc.xs4all.nl  Thu Nov  5 08:39:52 2015
From: albert at spenarnc.xs4all.nl (Albert van der Horst)
Date: 05 Nov 2015 13:39:52 GMT
Subject: Regular expressions
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <563b5c28$0$23757$e4fe514c@news.xs4all.nl>

Steven D'Aprano <steve at pearwood.info> writes:

>On Wed, 4 Nov 2015 07:57 pm, Peter Otten wrote:

>> I tried Tim's example
>>
>> $ seq 5 | grep '1*'
>> 1
>> 2
>> 3
>> 4
>> 5
>> $

>I don't understand this. What on earth is grep matching? How does "4"
>match "1*"?


>> which surprised me because I remembered that there usually weren't any
>> matching lines when I invoked grep instead of egrep by mistake. So I tried
>> another one
>>
>> $ seq 5 | grep '[1-3]+'
>> $
>>
>> and then headed for the man page. Apparently there is a subset called
>> "basic regular expressions":
>>
>> """
>>   Basic vs Extended Regular Expressions
>>        In basic regular expressions the meta-characters ?, +, {, |, (,
>>        and ) lose their special meaning; instead use  the  backslashed
>>        versions \?, \+, \{, \|, \(, and \).
>> """

>None of this appears relevant, as the metacharacter * is not listed. So
>what's going on?

* is so fundamental that it never looses it special meaning.
Same for [ .

* means zero more of the preceeding char.
This makes + superfluous (a mere convenience) as
    [1-3]+
can be expressed as
    [1-3][1-3]*

Note that [1-3]* matches the empty string. This happens a lot.

Groetjes Albert




>--
>Steven
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert at spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst



From python.list at tim.thechases.com  Thu Nov  5 09:00:00 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 5 Nov 2015 08:00:00 -0600
Subject: Regular expressions
In-Reply-To: <563b45fa$0$1593$c3e8da3$5496439d@news.astraweb.com>
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com>
 <mailman.6.1446627436.16136.python-list@python.org>
 <563abee1$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.48.1446712433.16136.python-list@python.org>
 <563b45fa$0$1593$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <20151105080000.6da70056@bigbox.christie.dr>

On 2015-11-05 23:05, Steven D'Aprano wrote:
> Oh the shame, I knew that. Somehow I tangled myself in a knot,
> thinking that it had to be 1 *followed by* zero or more characters.
> But of course it's not a glob, it's a regex.

But that's a good reminder of fnmatch/glob modules too.  Sometimes
all you need is to express a simple glob, in which case using a
regexp can cloud the clarity.

The overarching principle is to go for clarity & simplicity, rather
than favoring built-ins/glob/regex/parser modules all the time.

Want to test for presence in a string?  Just use the builtin "a in b"
test.  At the beginning/end?  Use .startswith()/.endswith() for
clarity.  Need to check if a string is purely
digits/alpha/alphanumerics/etc?  Use the
string .is{alnum,alpha,decimal,digit,identifier,lower,numeric,printable,space,title,upper}
methods on the string.

For simple wild-carding, use the fnmatch module to do simple
globbing.

For more complex pattern matching, you've got regexps.

Finally, for occasions when you're searching for repeated/nested
structures, using an add-on module like pyparsing will give you
clearer code.

Oh, and with regexps, people should be less afraid of verbose
multi-line strings with commenting

  r = re.compile(r"""
    ^                       # start of the string
    (?P<year>\d{4})         # capture 4 digits
    -                       # a literal dash
    (?P<month>\d{1,2})      # capture 1-2 digits
    -                       # another literal dash
    (?P<day>\d{1,2})        # capture 1-2 digits
    _                       # a literal underscore
    (?P<accountnum>         # capture the account-number
      [A-Z]{1,3}               # 1-3 letters
      \d+                      # followed by 1+ digits
      )
    \.txt                   # the extension of the file (ignored)
    $                       # the end of the string
    """, re.VERBOSE)

They are a LOT easier to come back to if you haven't touched the code
for a year.

-tkc





From mahanmarwat at gmail.com  Thu Nov  5 09:01:51 2015
From: mahanmarwat at gmail.com (Mahan Marwat)
Date: Thu, 5 Nov 2015 06:01:51 -0800 (PST)
Subject: Python Hidden Code
Message-ID: <de27cc67-9866-409d-aa83-5c48348018bb@googlegroups.com>

Repo `that` (Python Hidden Code) purpose is to collect all of the Python Easter Eggs, Idioms etc... in one place.
If you have something to contribute, please send PR.
Check it here: https://github.com/mahanmarwat/that


From mahanmarwat at gmail.com  Thu Nov  5 09:08:31 2015
From: mahanmarwat at gmail.com (Mahan Marwat)
Date: Thu, 5 Nov 2015 06:08:31 -0800 (PST)
Subject: =?UTF-8?B?U25ha2UgRXJyb3Ig8J+QjQ==?=
Message-ID: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>

When I am trying to paste this ? in Python 3.5.0 IDLE. It crashes.
Found it on this page: http://www.fileformat.info/info/unicode/char/1f40d/index.htm
Does Python have any problem with other snakes?


From rosuav at gmail.com  Thu Nov  5 09:15:53 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 6 Nov 2015 01:15:53 +1100
Subject: Python Hidden Code
In-Reply-To: <de27cc67-9866-409d-aa83-5c48348018bb@googlegroups.com>
References: <de27cc67-9866-409d-aa83-5c48348018bb@googlegroups.com>
Message-ID: <CAPTjJmovUhy39173w2POP6uOjDjTO5pJOE1cjJO7=4OTAMreww@mail.gmail.com>

On Fri, Nov 6, 2015 at 1:01 AM, Mahan Marwat <mahanmarwat at gmail.com> wrote:
> Repo `that` (Python Hidden Code) purpose is to collect all of the Python Easter Eggs, Idioms etc... in one place.
> If you have something to contribute, please send PR.
> Check it here: https://github.com/mahanmarwat/that

Cool! I've sent you a few PRs with small clarifications.

ChrisA


From __peter__ at web.de  Thu Nov  5 09:16:23 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 15:16:23 +0100
Subject: raw_input and break
References: <mailman.51.1446723514.16136.python-list@python.org>
 <0pI_x.14172$aq1.6942@fe58.am1>
Message-ID: <n1fobo$q3b$1@ger.gmane.org>

input/ldompeling at casema.nl wrote:

> In reply to "Peter Otten" who wrote the following:
> 
>> input/ldompeling at casema.nl wrote:
>> 
>> > >   choices = raw_input("letter s to stop:")
>> > 
>> > Oh no, this is not what I want. Now it is waiting for input when its go
>> > further with the script. Because I have an while True: so I want that
>> > the script go's continue only when I press a key then it must stop the
>> > script.
>> 
>> Solutions to that problem are OS-dependent. For Unix terminals
>> 
>> https://docs.python.org/2/faq/
>> library.html#how-do-i-get-a-single-keypress-at-a-time
>> 
>> shows one way which I used to write the contextmanager below:
>> 
>> $ cat capture_key.py
>> import termios, fcntl, sys, os
>> 
>> from contextlib import contextmanager
>> 
>> 
>> @contextmanager
>> def nonblocking(stdin=None):
>>     if stdin is None:
>>         stdin = sys.stdin
>> 
>>     fd = sys.stdin.fileno()
>> 
>>     oldterm = termios.tcgetattr(fd)
>>     newattr = termios.tcgetattr(fd)
>>     newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
>>     termios.tcsetattr(fd, termios.TCSANOW, newattr)
>> 
>>     oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
> Thanks for the reply. Is there no easy way to do so in python ?

If you are asking for a ready-made function in the standard library, I don't 
know one and I don't think there is one (there are recipes that work on top 
of curses though).

> I am using the raspberry pi with Wheezy and for the robot the GoPiGo which
> is connected on the raspberry pi. The GoPiGo board has his own code like:
> fwd()="forward" bwd()="backward" right()="right" left="left" and so on. I
> am just a dummie with python.

The code in capture_key.py may look a bit scary, but just as I took it 
without bothering the details you can take the resulting module without 
caring about the code in it. Alternatively you can search 

https://pypi.python.org

for a solution that you prefer.



From rosuav at gmail.com  Thu Nov  5 09:18:23 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 6 Nov 2015 01:18:23 +1100
Subject: =?UTF-8?B?UmU6IFNuYWtlIEVycm9yIPCfkI0=?=
In-Reply-To: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
References: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
Message-ID: <CAPTjJmpgb6GaWh0HG5QaZjSZJEeFr8bf1oWtBwHrBe6tHKzZ-A@mail.gmail.com>

On Fri, Nov 6, 2015 at 1:08 AM, Mahan Marwat <mahanmarwat at gmail.com> wrote:
> When I am trying to paste this ? in Python 3.5.0 IDLE. It crashes.
> Found it on this page: http://www.fileformat.info/info/unicode/char/1f40d/index.htm
> Does Python have any problem with other snakes?

Was this on Windows? The Windows builds of Tk have a problem with
astral characters, so you may not be able to use them there. Try it on
Linux, or try using a character with a four-digit codepoint.

Other GUI toolkits may do better (I've used Gtk on Windows with astral
characters, though not from Python), and it should be fine on any
modern Linux system.

ChrisA


From mahanmarwat at gmail.com  Thu Nov  5 09:31:29 2015
From: mahanmarwat at gmail.com (Mahan Marwat)
Date: Thu, 5 Nov 2015 06:31:29 -0800 (PST)
Subject: =?UTF-8?B?UmU6IFNuYWtlIEVycm9yIPCfkI0=?=
In-Reply-To: <mailman.55.1446733112.16136.python-list@python.org>
References: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
 <mailman.55.1446733112.16136.python-list@python.org>
Message-ID: <16d52451-d661-48c3-b03a-b2e013d9d01c@googlegroups.com>

> Was this on Windows?

Yeh, Window 10.


From input/ldompeling at casema.nl  Thu Nov  5 09:34:27 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Thu, 05 Nov 2015 14:34:27 GMT
Subject: raw_input and break
References: <mailman.54.1446733002.16136.python-list@python.org>
Message-ID: <TNJ_x.13318$aD7.1426@fe55.am1>

>The code in capture_key.py may look a bit scary, but just as I took it
>without bothering the details you can take the resulting module without
>caring about the code in it. Alternatively you can search

>https://pypi.python.org

Thanks for the link. I realy appreciate it.
Can you also tell me what I am looking for in https://pypi.python.org for a result.

Thanks
 















In reply to "Peter Otten" who wrote the following:

> input/ldompeling at casema.nl wrote:
> 
> > In reply to "Peter Otten" who wrote the following:
> > 
> > > input/ldompeling at casema.nl wrote:
> > > 
> > > > >   choices = raw_input("letter s to stop:")
> > > > 
> > > > Oh no, this is not what I want. Now it is waiting for input when its go
> > > > further with the script. Because I have an while True: so I want that
> > > > the script go's continue only when I press a key then it must stop the
> > > > script.
> > > 
> > > Solutions to that problem are OS-dependent. For Unix terminals
> > > 
> > > https://docs.python.org/2/faq/
> > > library.html#how-do-i-get-a-single-keypress-at-a-time
> > > 
> > > shows one way which I used to write the contextmanager below:
> > > 
> > > $ cat capture_key.py
> > > import termios, fcntl, sys, os
> > > 
> > > from contextlib import contextmanager
> > > 
> > > @contextmanager
> > > def nonblocking(stdin=None):
> > >     if stdin is None:
> > >         stdin = sys.stdin
> > > 
> > >     fd = sys.stdin.fileno()
> > > 
> > >     oldterm = termios.tcgetattr(fd)
> > >     newattr = termios.tcgetattr(fd)
> > >     newattr[3] = newattr[3] & ~termios.ICANON & ~termios.ECHO
> > >     termios.tcsetattr(fd, termios.TCSANOW, newattr)
> > > 
> > >     oldflags = fcntl.fcntl(fd, fcntl.F_GETFL)
> > Thanks for the reply. Is there no easy way to do so in python ?
> 
> If you are asking for a ready-made function in the standard library, I don't
> know one and I don't think there is one (there are recipes that work on top
> of curses though).
> 
> > I am using the raspberry pi with Wheezy and for the robot the GoPiGo which
> > is connected on the raspberry pi. The GoPiGo board has his own code like:
> > fwd()="forward" bwd()="backward" right()="right" left="left" and so on. I
> > am just a dummie with python.
> 
> The code in capture_key.py may look a bit scary, but just as I took it
> without bothering the details you can take the resulting module without
> caring about the code in it. Alternatively you can search
> 
> https://pypi.python.org
> 
> for a solution that you prefer.




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From Seymore4Head at Hotmail.invalid  Thu Nov  5 10:07:06 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Thu, 05 Nov 2015 10:07:06 -0500
Subject: Regular expressions
References: <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <1i3l3b9836hatsuoopak5gtg2c38g49kb1@4ax.com>
 <563aa8be$0$1596$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <ftrm3btf2a8ik9h1uora8p1ptq4sqand60@4ax.com>

On Thu, 05 Nov 2015 11:54:20 +1100, Steven D'Aprano
<steve at pearwood.info> wrote:

>On Thu, 5 Nov 2015 10:02 am, Seymore4Head wrote:
>
>> So far the only use I have for regex is to replace slicing, but I
>> think it is an improvement.
>
>I don't understand this. This is like saying "so far the only use I have for
>a sandwich press is to replace my coffee pot". Regular expressions and
>slicing do very different things.
>
>Slicing extracts substrings, given known starting and ending positions:
>
>
>py> the_str = "Now is the time for all good men..."
>py> the_str[7:12]
>'the t'
>
>
>Regular expressions don't extract substrings with known start/end positions.
>They *find* matching text, giving a search string with metacharacters. (If
>there are no metacharacters in your search string, you shouldn't use a
>regex. str.find will be significantly faster and more convenient.)
>
>Slicing is not about finding text, it is about extracting text once you've
>already found it. So they are complementary, not alternatives.

Here is an example of the text we are slicing apart.

>From stephen.marquard at uct.ac.za Sat Jan  5 09:14:16 2008
Return-Path: <postmaster at collab.sakaiproject.org>
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Date: Sat, 5 Jan 2008 09:12:18 -0500
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From: stephen.marquard at uct.ac.za

The practice problems are something like pull out all the email
addresses or pull out the days of the week and give the most common.



From random832 at fastmail.com  Thu Nov  5 10:19:05 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 05 Nov 2015 10:19:05 -0500
Subject: What does =?utf-8?B?4oCcZ3JlcOKAnQ==?= stand for?
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
Message-ID: <87pozotqxi.fsf@fastmail.com>

Chris Angelico <rosuav at gmail.com> writes:
> As someone who grew up on MS-DOS, I'd like to mention that EDLIN's
> value wasn't in the obvious places. There were two features it had
> that most other editors didn't: firstly, it would read only as much of
> the file as it needed, so you could edit a file larger than available
> memory; and secondly, all commands came from stdin, which could be
> redirected - making it a poor man's 'sed'. Using EDLIN for regular
> file editing was never the normal thing.

Of course, both of those things are also true of ed.

And I found it a bit interesting that use in scripts was mentioned as a
contrast between sed and ed, when the original way patches were
distributed (and diff still has an option to generate these) was as ed
scripts.



From olivier.adret02 at gmail.com  Thu Nov  5 10:24:38 2015
From: olivier.adret02 at gmail.com (olivier)
Date: Thu, 5 Nov 2015 16:24:38 +0100
Subject: Olivier Adret
Message-ID: <563B74B6.80402@gmail.com>

      Je vais essayer de programmer en python. On verra bien !


From robin at reportlab.com  Thu Nov  5 11:56:19 2015
From: robin at reportlab.com (Robin Becker)
Date: Thu, 5 Nov 2015 16:56:19 +0000
Subject: llewellynBH@gmail.com
Message-ID: <563B8A33.2010305@chamonix.reportlab.co.uk>

Hi,

did you find your phone?
-- 
Robin Becker



From __peter__ at web.de  Thu Nov  5 12:06:31 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 18:06:31 +0100
Subject: raw_input and break
References: <mailman.54.1446733002.16136.python-list@python.org>
 <TNJ_x.13318$aD7.1426@fe55.am1>
Message-ID: <n1g2ao$a7h$1@ger.gmane.org>

input/ldompeling at casema.nl wrote:

>>The code in capture_key.py may look a bit scary, but just as I took it
>>without bothering the details you can take the resulting module without
>>caring about the code in it. Alternatively you can search
> 
>>https://pypi.python.org
> 
> Thanks for the link. I realy appreciate it.
> Can you also tell me what I am looking for in https://pypi.python.org for
> a result.

I didn't have a particular module in mind. Pypy, or the "Python Package 
Index", is a repository for all kinds of modules and libraries. If you don't 
yet feel comfortable looking around (peferrably using the search engine of 
your choice) and experimenting a bit I recommend that you try the piece of 
code I posted (or wait for someone else to chime in with a better 
suggestion).



From __peter__ at web.de  Thu Nov  5 12:15:12 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 05 Nov 2015 18:15:12 +0100
Subject: llewellynBH@gmail.com
References: <563B8A33.2010305@chamonix.reportlab.co.uk>
Message-ID: <n1g2r1$gtn$1@ger.gmane.org>

Robin Becker wrote:

> Hi,
> 
> did you find your phone?

If not -- it's probably on comp.lang.perl.misc

Glad to be of help ;)



From input/ldompeling at casema.nl  Thu Nov  5 12:28:36 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Thu, 05 Nov 2015 17:28:36 GMT
Subject: raw_input and break
References: <mailman.58.1446743214.16136.python-list@python.org>
Message-ID: <8lM_x.24516$cf7.4240@fx02.am1>

Oke, lets try your code.Can you help me with that.
This is my code:
-------------------------------------------------
from gopigo import *
import time

set_right_speed(150)
set_left_speed(105)
enable_servo()
fwd()
print("forward 1x")
time.sleep(4)
stop()

while True:
    servo(90)
    mindist = 80

    if mindist > us_dist(15):
        bwd()
        print ("backward 1x")
        time.sleep(2)
        stop()
        right()
        time.sleep(1)
        stop()
        print("right 1x")
        time.sleep(2)
        stop()
        fwd()
        print("forward 2x")
        time.sleep(3)
        stop()
        left()
        time.sleep(1)
        print("left 1x")
        stop()
        fwd()
        print("forward 3x")
        time.sleep(2)
        stop()
------------------------------------------------------
In reply to "Peter Otten" who wrote the following:

> input/ldompeling at casema.nl wrote:
> 
> > > The code in capture_key.py may look a bit scary, but just as I took it
> > > without bothering the details you can take the resulting module without
> > > caring about the code in it. Alternatively you can search
> > 
> > > https://pypi.python.org
> > 
> > Thanks for the link. I realy appreciate it.
> > Can you also tell me what I am looking for in https://pypi.python.org for
> > a result.
> 
> I didn't have a particular module in mind. Pypy, or the "Python Package
> Index", is a repository for all kinds of modules and libraries. If you don't
> yet feel comfortable looking around (peferrably using the search engine of
> your choice) and experimenting a bit I recommend that you try the piece of
> code I posted (or wait for someone else to chime in with a better
> suggestion).




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From mdaglow at daglowconsulting.com  Thu Nov  5 12:39:26 2015
From: mdaglow at daglowconsulting.com (Marta Daglow)
Date: Thu, 5 Nov 2015 09:39:26 -0800
Subject: Top Engineers
Message-ID: <883ad76fb70512dfaec55696045dfe5f@mail.gmail.com>

Hi,

I'm working closely with co-founders of a top startup in SoMa.  We are in
the client services space and have created innovative solutions in
optimizing the first time user experience for small through large
enterprise companies.   We already have a strong client list of household
names.  We are looking for smart and amazing engineers who are creative
thinkers, fascinated by mobile technology, enjoy working in teams of smart
and accomplished people, and are meticulous in coding.  We would consider
some remote work.

Whether you are right out of college or have lots of engineering
experience we'd like to talk with you.  Pay from $80K - $240K (plus stock
with a co that has not needed VC funds to get started). Top leaders.  Top
culture.  Career defining role.

Please email me at mdaglow at daglowconsulting.com to set up a time to talk.


From robin at reportlab.com  Thu Nov  5 12:56:20 2015
From: robin at reportlab.com (Robin Becker)
Date: Thu, 5 Nov 2015 17:56:20 +0000
Subject: llewellynBH@gmail.com
In-Reply-To: <n1g2r1$gtn$1@ger.gmane.org>
References: <563B8A33.2010305@chamonix.reportlab.co.uk>
 <n1g2r1$gtn$1@ger.gmane.org>
Message-ID: <563B9844.4040601@chamonix.reportlab.co.uk>

On 05/11/2015 17:15, Peter Otten wrote:
> Robin Becker wrote:
>
>> Hi,
>>
>> did you find your phone?
>
> If not -- it's probably on comp.lang.perl.misc
>
> Glad to be of help ;)
>
weird no idea why this ended up here; thunderbird is a bit strange today
-mis-guidedly yrs-
Robin Becker



From robin at reportlab.com  Thu Nov  5 12:56:20 2015
From: robin at reportlab.com (Robin Becker)
Date: Thu, 5 Nov 2015 17:56:20 +0000
Subject: llewellynBH@gmail.com
In-Reply-To: <n1g2r1$gtn$1@ger.gmane.org>
References: <563B8A33.2010305@chamonix.reportlab.co.uk>
 <n1g2r1$gtn$1@ger.gmane.org>
Message-ID: <563B9844.4040601@chamonix.reportlab.co.uk>

On 05/11/2015 17:15, Peter Otten wrote:
> Robin Becker wrote:
>
>> Hi,
>>
>> did you find your phone?
>
> If not -- it's probably on comp.lang.perl.misc
>
> Glad to be of help ;)
>
weird no idea why this ended up here; thunderbird is a bit strange today
-mis-guidedly yrs-
Robin Becker


From lac at openend.se  Thu Nov  5 13:02:49 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 05 Nov 2015 19:02:49 +0100
Subject: Top Engineers
In-Reply-To: <883ad76fb70512dfaec55696045dfe5f@mail.gmail.com>
References: <883ad76fb70512dfaec55696045dfe5f@mail.gmail.com>
Message-ID: <201511051802.tA5I2nC2002323@fido.openend.se>

In a message of Thu, 05 Nov 2015 09:39:26 -0800, Marta Daglow writes:
   <blather blather I want to hire somebody special to work in SoMa>

It is extremely unprofessional to spam an international mailing 
list with a large readership with such things.  And very parochial --
do you have any idea how many neighbourhoods there are in the world
that get called 'SoMa', precisely because they are South of some
large Street whose name begins with 'Ma'?

If you are trying to find people, we have a jobs board for that.
https://www.python.org/jobs/
Use it.  Stop damaging your reputation by posting things here.

Laura Creighton


From invalid at invalid.invalid  Thu Nov  5 13:29:50 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Thu, 5 Nov 2015 18:29:50 +0000 (UTC)
Subject: What does =?UTF-8?Q?=E2=80=9Cgrep=E2=80=9D?= stand for?
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
Message-ID: <n1g76u$85u$1@reader1.panix.com>

On 2015-11-05, Random832 <random832 at fastmail.com> wrote:
> Chris Angelico <rosuav at gmail.com> writes:

>> As someone who grew up on MS-DOS, I'd like to mention that EDLIN's
>> value wasn't in the obvious places. There were two features it had
>> that most other editors didn't: firstly, it would read only as much
>> of the file as it needed, so you could edit a file larger than
>> available memory; and secondly, all commands came from stdin, which
>> could be redirected - making it a poor man's 'sed'. Using EDLIN for
>> regular file editing was never the normal thing.
>
> Of course, both of those things are also true of ed.

Well, maybe not for you.  I knew people who (yonks ago) used 'ed' for
regular file editing.  And I remember using the VMS line-editor for
regular file editing for a couple years before before a full-screen
editor was available.

-- 
Grant Edwards               grant.b.edwards        Yow! I always have fun
                                  at               because I'm out of my
                              gmail.com            mind!!!


From random832 at fastmail.com  Thu Nov  5 14:56:14 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 05 Nov 2015 14:56:14 -0500
Subject: What does =?utf-8?B?4oCcZ3JlcOKAnQ==?= stand for?
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me>
 <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
Message-ID: <87oaf8fcf5.fsf@fastmail.com>

Grant Edwards <invalid at invalid.invalid> writes:
> On 2015-11-05, Random832 <random832 at fastmail.com> wrote:
>> Of course, both of those things are also true of ed.
>
> Well, maybe not for you.  I knew people who (yonks ago) used 'ed' for
> regular file editing.  And I remember using the VMS line-editor for
> regular file editing for a couple years before before a full-screen
> editor was available.

Er, I think my quoting was unclear. I meant the two features he
mentioned (not loading the whole file in memory, and accepting commands
from a redirected input file) applied.

Of course, AIUI ed had always _also_ been used for scripts. But I never
meant to imply that it wasn't used as an interactive editor, at least
before vi came around.



From auriocus at gmx.de  Thu Nov  5 15:02:15 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 5 Nov 2015 21:02:15 +0100
Subject: =?UTF-8?Q?Re:_Snake_Error_=f0=9f=90=8d?=
In-Reply-To: <mailman.55.1446733112.16136.python-list@python.org>
References: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
 <mailman.55.1446733112.16136.python-list@python.org>
Message-ID: <n1gcg0$peu$1@dont-email.me>

Am 05.11.15 um 15:18 schrieb Chris Angelico:
> On Fri, Nov 6, 2015 at 1:08 AM, Mahan Marwat <mahanmarwat at gmail.com> wrote:
>> When I am trying to paste this ? in Python 3.5.0 IDLE. It crashes.
>> Found it on this page: http://www.fileformat.info/info/unicode/char/1f40d/index.htm
>> Does Python have any problem with other snakes?
>
> Was this on Windows? The Windows builds of Tk have a problem with
> astral characters, so you may not be able to use them there. Try it on
> Linux

Tk does only handle BMP characters. It's a restriction deep inside the 
codebase of Tcl 8, which will be lifted only in (the future) Tcl 9. 
Howver, it should not crash, rather paste a U+FFFD character. X-Post to 
comp.lang.tcl. Can you check the Tk version you use? Try:

import tkinter
tkinter.Tk().eval("info patchlevel")

	Christian



From invalid at invalid.invalid  Thu Nov  5 15:19:39 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Thu, 5 Nov 2015 20:19:39 +0000 (UTC)
Subject: What does =?UTF-8?Q?=E2=80=9Cgrep=E2=80=9D?= stand for?
References: <662g3blobme52hfoududj27err185v2npm@4ax.com>
 <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
Message-ID: <n1gdkr$mce$1@reader1.panix.com>

On 2015-11-05, Random832 <random832 at fastmail.com> wrote:
> Grant Edwards <invalid at invalid.invalid> writes:
>> On 2015-11-05, Random832 <random832 at fastmail.com> wrote:
>>> Of course, both of those things are also true of ed.
>>
>> Well, maybe not for you.  I knew people who (yonks ago) used 'ed' for
>> regular file editing.  And I remember using the VMS line-editor for
>> regular file editing for a couple years before before a full-screen
>> editor was available.
>
> Er, I think my quoting was unclear.

I think it was more a case of my reading being unclear.  It's pretty
clear upon re-reading what you wrote that you didn't mean that nobody
used 'ed' for regular file editing.

Though I used a line-editor for a while on VMS, I was never very good
at it, and abanded it for a full-screen editor at he first
opportunity.  But, if you ever get a chance to watching somebody who
_is_ good at 'ed', it's something you'll remember...

-- 
Grant Edwards               grant.b.edwards        Yow! I want a VEGETARIAN
                                  at               BURRITO to go ... with
                              gmail.com            EXTRA MSG!!


From RobinsW1 at sutterhealth.org  Thu Nov  5 15:48:11 2015
From: RobinsW1 at sutterhealth.org (Robinson, Wendy)
Date: Thu, 5 Nov 2015 12:48:11 -0800
Subject: Puzzled
In-Reply-To: <201511011020.tA1AKYAM004182@fido.openend.se>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
Message-ID: <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>

Well... I still can't get this to work. I guess I'll just uninstall it.
It's a bummer that there's no help on basic startup like this.

Wendy Robinson
Audit Analyst
(916)?566-4994 phone



NOTICE OF CONFIDENTIALITY: This email is for the sole use of the intended recipient and may contain material that is confidential and protected by state and federal regulations.? If you are not the intended recipient please immediately delete it and contact the sender. 

-----Original Message-----
From: Laura Creighton [mailto:lac at openend.se] 
Sent: Sunday, November 01, 2015 2:21 AM
To: Robinson, Wendy
Cc: 'python-list at python.org'; lac at openend.se
Subject: Re: Puzzled

In a message of Fri, 30 Oct 2015 09:20:23 -0700, "Robinson, Wendy" writes:
>Hi there,
>I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
>This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.
>
>I tried running the Repair installation, but that did not help.
>
>Any suggestions?
>
>Thank you
>
>Wendy Robinson
>Audit Analyst
>(916) 566-4994 phone

Paste in the Full traceback you get from the console.
Also check and see that the console is actually running the 3.5 you installed, and not some other python, like 2.7 you might have lying around.  

Laura


From breamoreboy at yahoo.co.uk  Thu Nov  5 16:52:24 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 5 Nov 2015 21:52:24 +0000
Subject: llewellynBH@gmail.com
In-Reply-To: <563B8A33.2010305@chamonix.reportlab.co.uk>
References: <563B8A33.2010305@chamonix.reportlab.co.uk>
Message-ID: <n1gj31$5jh$1@ger.gmane.org>

On 05/11/2015 16:56, Robin Becker wrote:
> Hi,
>
> did you find your phone?

Same answer as to the question "Is Vic there?", no :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From lac at openend.se  Thu Nov  5 18:10:45 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 06 Nov 2015 00:10:45 +0100
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
Message-ID: <201511052310.tA5NAjAk026602@fido.openend.se>

In a message of Thu, 05 Nov 2015 12:48:11 -0800, "Robinson, Wendy" writes:
>Well... I still can't get this to work. I guess I'll just uninstall it.
>It's a bummer that there's no help on basic startup like this.
>
>Wendy Robinson
>Audit Analyst
>(916)?566-4994 phone

There is enormous amount of help available.  But we need to know more
about what your problem is, and how it presents itself before we can
start tracking down what your problem is, which is why I wanted a
traceback.

>>Hi there,
>>I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
>>This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.

See, this is where your problem is. There is a conceptual problem in
understanding what you meant by 'tried some basic programs successfully'
versus 'running py files at the >>> prompt'.

Either you didn't use the Python console -- the thing that is showing 
you the '>>>' yesterday, and thus the programs that were working
yesterday are now working every bit as well as they did then, and
your problem is that you do not know how to use the python console.

Or you did use the console before, and they worked there, and now
you have NameErrors.

I think the problem is the first sort.
I think that you opened up the python console and then 
typed in something like 'myprogram.py' expecting the console
to run the myprogram.  Instead you got something like this:

Python 3.5.0rc1 (default, Aug 12 2015, 14:57:46) 
[GCC 5.2.1 20150808] on linux
Type "help", "copyright", "credits" or "license" for more information.
 >>> myprogram.py
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'myprogram' is not defined
 >>> 

If this is what happened then your python is fine.  You just do not
know how the interactive console works.  It doesn't run files 
like this.

See:https://docs.python.org/3.5/tutorial/introduction.html

You type code at the console and get responses back.

If, on the other hand, this is not your problem, then we need a
traceback --- and what I posted above was a traceback -- so that
we can see what caused the NameError.  

Laura 



From RobinsW1 at sutterhealth.org  Thu Nov  5 19:04:35 2015
From: RobinsW1 at sutterhealth.org (Robinson, Wendy)
Date: Thu, 5 Nov 2015 16:04:35 -0800
Subject: Puzzled
In-Reply-To: <201511052310.tA5NAjAk026602@fido.openend.se>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
 <201511052310.tA5NAjAk026602@fido.openend.se>
Message-ID: <4CFEDC132D44AC49BA0E91FBEB947119084A8D60B8@DCBL123VX.root.sutterhealth.org>

Hmmm... fair enough.  I sent the traceback though, on Monday.
I'll give the intro a read again.  I've probably missed something basic.

Wendy Robinson
Audit Analyst
(916)?566-4994 phone



NOTICE OF CONFIDENTIALITY: This email is for the sole use of the intended recipient and may contain material that is confidential and protected by state and federal regulations.? If you are not the intended recipient please immediately delete it and contact the sender. 


-----Original Message-----
From: Laura Creighton [mailto:lac at openend.se] 
Sent: Thursday, November 05, 2015 3:11 PM
To: Robinson, Wendy
Cc: 'Laura Creighton'; 'python-list at python.org'; lac at openend.se
Subject: Re: Puzzled

In a message of Thu, 05 Nov 2015 12:48:11 -0800, "Robinson, Wendy" writes:
>Well... I still can't get this to work. I guess I'll just uninstall it.
>It's a bummer that there's no help on basic startup like this.
>
>Wendy Robinson
>Audit Analyst
>(916)?566-4994 phone

There is enormous amount of help available.  But we need to know more about what your problem is, and how it presents itself before we can start tracking down what your problem is, which is why I wanted a traceback.

>>Hi there,
>>I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
>>This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.

See, this is where your problem is. There is a conceptual problem in understanding what you meant by 'tried some basic programs successfully'
versus 'running py files at the >>> prompt'.

Either you didn't use the Python console -- the thing that is showing you the '>>>' yesterday, and thus the programs that were working yesterday are now working every bit as well as they did then, and your problem is that you do not know how to use the python console.

Or you did use the console before, and they worked there, and now you have NameErrors.

I think the problem is the first sort.
I think that you opened up the python console and then typed in something like 'myprogram.py' expecting the console to run the myprogram.  Instead you got something like this:

Python 3.5.0rc1 (default, Aug 12 2015, 14:57:46) [GCC 5.2.1 20150808] on linux Type "help", "copyright", "credits" or "license" for more information.
 >>> myprogram.py
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'myprogram' is not defined  >>> 

If this is what happened then your python is fine.  You just do not know how the interactive console works.  It doesn't run files like this.

See:https://docs.python.org/3.5/tutorial/introduction.html

You type code at the console and get responses back.

If, on the other hand, this is not your problem, then we need a traceback --- and what I posted above was a traceback -- so that we can see what caused the NameError.  

Laura 


From torriem at gmail.com  Thu Nov  5 20:35:33 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 05 Nov 2015 18:35:33 -0700
Subject: Puzzled
In-Reply-To: <201511052310.tA5NAjAk026602@fido.openend.se>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
 <201511052310.tA5NAjAk026602@fido.openend.se>
Message-ID: <563C03E5.3010608@gmail.com>

On 11/05/2015 04:10 PM, Laura Creighton wrote:
> In a message of Thu, 05 Nov 2015 12:48:11 -0800, "Robinson, Wendy" writes:
>> Well... I still can't get this to work. I guess I'll just uninstall it.
>> It's a bummer that there's no help on basic startup like this.
>>
>> Wendy Robinson
>> Audit Analyst
>> (916) 566-4994 phone
> 
> There is enormous amount of help available.  But we need to know more
> about what your problem is, and how it presents itself before we can
> start tracking down what your problem is, which is why I wanted a
> traceback.

Indeed there was quite a lot of help given to her on this list but she
didn't reply to any of those suggestions.  Pretty discouraging to those
who want to help out.


From wangq at travelsky.com  Thu Nov  5 21:33:58 2015
From: wangq at travelsky.com (wangq at travelsky.com)
Date: Fri, 6 Nov 2015 10:33:58 +0800
Subject: Question about math.pi is mutable
Message-ID: <201511061033583772468@travelsky.com>

Hello, python-list guys:

    I am a newbie of python from Beijing. China. 
    I have a question about "math.pi". 
    As you can see in the attachment, why i can modify "math.pi"?
    (in "mathmodule.c" "pi" is a "static const double")
    
Thank you in advance!

Best Wishes?

From tjreedy at udel.edu  Thu Nov  5 22:18:34 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 5 Nov 2015 22:18:34 -0500
Subject: =?UTF-8?Q?Re:_Snake_Error_=f0=9f=90=8d?=
In-Reply-To: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
References: <7c531168-539c-45ef-bb1d-bca713c383cc@googlegroups.com>
Message-ID: <n1h66c$4ka$1@ger.gmane.org>

On 11/5/2015 9:08 AM, Mahan Marwat wrote:
> When I am trying to paste this ? in Python 3.5.0 IDLE. It crashes.

https://bugs.python.org/issue13153

If you run 'python -m idlelib' from command line, you will see a traceback.

-- 
Terry Jan Reedy




From orgnut at yahoo.com  Thu Nov  5 22:36:11 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Thu, 5 Nov 2015 19:36:11 -0800
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <mailman.67.1446772690.16136.python-list@python.org>
References: <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
 <n1gdkr$mce$1@reader1.panix.com>
 <mailman.67.1446772690.16136.python-list@python.org>
Message-ID: <NtKdnfI0w7uxvaHLnZ2dnUU7-cednZ2d@giganews.com>

On 11/05/2015 05:18 PM, Dennis Lee Bieber wrote:
> On Thu, 5 Nov 2015 20:19:39 +0000 (UTC), Grant Edwards
> <invalid at invalid.invalid> declaimed the following:
>
>> Though I used a line-editor for a while on VMS, I was never very good
>> at it, and abanded it for a full-screen editor at he first
>> opportunity.  But, if you ever get a chance to watching somebody who
>> _is_ good at 'ed', it's something you'll remember...
>
> 	I didn't convert to EDT until DEC dropped SOS... And then shortly later
> I keymapped the Blaise ([Alcor] Pascal) editor on the TRS-80 Mod-III to
> replicate EDT (as much as possible, given only three function keys on the
> numeric pad)
>
> 	The Amiga used to have two standard editors -- a screen editor and a
> line editor; as I recall the line editor supported a file window, so one
> could edit large files by making a single direction pass using a smaller
> window and a script. Later the screen editor gained ARexx support, so one
> could script it using ARexx. (And by then they also included a form of
> microEMACS, my C compiler had a look-alike vi editor... and a later C
> compiler had another editor integrated to the compiler so that error
> message reports could trigger the editor to open the file and move to the
> error position)
>
Anyone besides me remember the CP/M editor Mince (Mince Is Not Complete EMACS)?
It was an emacs-like editor, without any e-Lisp or other way of extending it.  I believe it was 
my first exposure to a screen-oriented editor.  I quite liked it at that time (but that was a 
looonnng time ago!)

      -=- Larry -=-



From abhishek.mallela at gmail.com  Thu Nov  5 22:54:01 2015
From: abhishek.mallela at gmail.com (Abhishek)
Date: Thu, 5 Nov 2015 19:54:01 -0800 (PST)
Subject: RuntimeError: The size of the array returned by func does not match
 the size of y0
Message-ID: <3ef62cda-560c-4eb9-87f0-f91a3f4d653b@googlegroups.com>

I have recently switched from programming heavily in MATLAB to programming in Python. Hence I am having some issues running the Python code that I have written. I am using IPython with Anaconda2 on Windows 7 and using numPy and SciPy to integrate a system of ordinary differential equations. I have generalized the system of ODEs for any number 'N' of them.

I have two versions of code that do the same thing, and give the same error message. One version uses 'exec' and 'eval' heavily, and the other uses arrays heavily. Here is my code for the array version:

----------------------------------------------------------------------
import numpy as np
import matplotlib.pyplot as plt
from scipy.integrate import odeint

#Constants and parameters
N = 2
K00 = np.logspace(0,3,101,10)
len1 = len(K00)
epsilon = 0.01
y0 = [0]*(3*N/2+3)
u1 = 0
u2 = 0
u3 = 0
Kplot = np.zeros((len1,1))
Pplot = np.zeros((len1,1))
S = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
KS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
PS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
Splot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
KSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
PSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]

for series in range(0,len1):
    K0 = K00[series]
    Q = 10
    r1 = 0.0001
    r2 = 0.001
    a = 0.001
    d = 0.001
    k = 0.999
    S10 = 1e5
    P0 = 1
    tfvec = np.tile(1e10,(1,5))
    tf = tfvec[0,0]
    time = np.linspace(0,tf,len1)

    #Defining dy/dt's
    def f(y,t):
        for alpha in range(0,(N/2+1)):
            S[alpha] = y[alpha]
        for beta in range((N/2)+1,N+1):
            KS[beta-N/2-1] = y[beta]
        for gamma in range(N+1,3*N/2+1):
            PS[gamma-N] = y[gamma]
        K = y[3*N/2+1]
        P = y[3*N/2+2]

        # The model equations
        ydot = np.zeros((3*N/2+3,1))
        B = range((N/2)+1,N+1)
        G = range(N+1,3*N/2+1)
        runsumPS = 0
        runsum1 = 0
        runsumKS = 0 
        runsum2 = 0

        for m in range(0,N/2):
            runsumPS = runsumPS + PS[m+1]
            runsum1 = runsum1 + S[m+1]
            runsumKS = runsumKS + KS[m]
            runsum2 = runsum2 + S[m]    
            ydot[B[m]] = a*K*S[m]-(d+k+r1)*KS[m]

        for i in range(0,N/2-1):
            ydot[G[i]] = a*P*S[i+1]-(d+k+r1)*PS[i+1]

        for p in range(1,N/2):
            ydot[p] = -S[p]*(r1+a*K+a*P)+k*KS[p-1]+ \
                      d*(PS[p]+KS[p])

        ydot[0] = Q-(r1+a*K)*S[0]+d*KS[0]+k*runsumPS
        ydot[N/2] = k*KS[N/2-1]-(r2+a*P)*S[N/2]+ \
                    d*PS[N/2]
        ydot[G[N/2-1]] = a*P*S[N/2]-(d+k+r2)*PS[N/2]
        ydot[3*N/2+1] = (d+k+r1)*runsumKS-a*K*runsum2
        ydot[3*N/2+2] = (d+k+r1)*(runsumPS-PS[N/2])- \
                        a*P*runsum1+(d+k+r2)*PS[N/2]
        
        for j in range(0,3*N/2+3):
            return ydot[j] 
                                                                                           
    # Initial conditions
    y0[0] = S10
    for i in range(1,3*N/2+1):
        y0[i] = 0
    y0[3*N/2+1] = K0
    y0[3*N/2+2] = P0
    
    # Solve the DEs
    soln = odeint(f,y0,time,mxstep = 5000)
    for alpha in range(0,(N/2+1)):
        S[alpha] = soln[:,alpha]
    for beta in range((N/2)+1,N+1):
        KS[beta-N/2-1] = soln[:,beta]   
    for gamma in range(N+1,3*N/2+1):
        PS[gamma-N] = soln[:,gamma]
     
    for alpha in range(0,(N/2+1)):
        Splot[alpha][series] = soln[len1-1,alpha]
    for beta in range((N/2)+1,N+1):
        KSplot[beta-N/2-1][series] = soln[len1-1,beta]
    for gamma in range(N+1,3*N/2+1):
        PSplot[gamma-N][series] = soln[len1-1,gamma]
  
    for alpha in range(0,(N/2+1)):
        u1 = u1 + Splot[alpha]
    for beta in range((N/2)+1,N+1):
        u2 = u2 + KSplot[beta-N/2-1]
    for gamma in range(N+1,3*N/2+1):
        u3 = u3 + PSplot[gamma-N]

    K = soln[:,3*N/2+1]
    P = soln[:,3*N/2+2]
    Kplot[series] = soln[len1-1,3*N/2+1]
    Pplot[series] = soln[len1-1,3*N/2+2]
    utot = u1+u2+u3

#Plot
plt.plot(np.log10(K00),utot[:,0])
plt.show()
----------------------------------------------------------------------
ERROR MESSAGE:
RuntimeError: The size of the array returned by func (1) does not match the size of y0 (6).
----------------------------------------------------------------------

I am facing a RuntimeError in the ODE integrator step. Please help me resolve this. Thanks in advance.


From input/ldompeling at casema.nl  Fri Nov  6 00:08:59 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Fri, 06 Nov 2015 05:08:59 GMT
Subject: raw_input and break
References: <mailman.66.1446772190.16136.python-list@python.org>
Message-ID: <LBW_x.37419$pB.28644@fe37.am1>

He,
Thank you for making some time for it.
Is this your code ?
I am also using python 3

I got an error with execute the scipt:
-----------------------------------------------------------------------

Enter command> Traceback (most recent call last):
  File "test06.py", line 44, in <module>
    for (dir, tm) in SEQUENCE:
NameError: name 'SEQUENCE' is not defined
-----------------------------------------------------------------------

import time
import threading

set_right_speed(150)
set_left_speed(105)

def cmdHandler():
        global notDone
        while True:
                cmd = raw_input("Enter command> ").lower()
                if cmd.startswith("s"):
                        notDone = False
                        break
                else:
                        print ("Unimplemented command: %s") % cmd

cmdThread = threading.Thread(target=cmdHandler)
cmdThread.start()
def move(drct, dly):
        if drct == FORWARD:
                fwd()
                print ("Forward")
        elif drct == BACKWARD:
                bwd()
                print ("Backward")
        elif drct == LEFT:
                left()
                print ("Left")
        elif drct == RIGHT:
                right()
                print ("Right")
        else:
                print ("Invalid command: %s") % drct
        time.sleep(dly)
        stop()

notDone = True

servo(90)
mindist = 80

while notDone:
        if mindist > us_dist(15):
                for (dir, tm) in SEQUENCE:
                        move(dir, tm)

---------------------------------------------------------------------------------------------
In reply to "Dennis Lee Bieber" who wrote the following:

> On Thu, 05 Nov 2015 17:28:36 GMT, input/ldompeling at casema.nl declaimed the
> following:
> 
> > Oke, lets try your code.Can you help me with that.
> > This is my code:
> > -------------------------------------------------
> > from gopigo import *
> > import time
> > 
> > set_right_speed(150)
> > set_left_speed(105)
> 
>  Is there a typo there? If those are setting rotation speeds for
> independent drive wheels, you will have a slow left turn enabled.
> 
> > enable_servo()
> > fwd()
> > print("forward 1x")
> > time.sleep(4)
> > stop()
> > 
> > while True:
> >    servo(90)
> >    mindist = 80
> > 
> >    if mindist > us_dist(15):
> 
>  "mindist" will always be 80 -- there is no code shown below that ever
> changes it (so the above assignment can be put before the "while"
> statement). That means your us_dist() function must somewhere return a
> value greater than 80.
> 
> >        bwd()
> >        print ("backward 1x")
> >        time.sleep(2)
> >        stop()
> >        right()
> >        time.sleep(1)
> >        stop()
> >        print("right 1x")
> >        time.sleep(2)
> 
>  You stopped the right() call before ever doing any output
> 
> >        stop()
> >        fwd()
> >        print("forward 2x")
> >        time.sleep(3)
> >        stop()
> >        left()
> >        time.sleep(1)
> >        print("left 1x")
> >        stop()
> >        fwd()
> >        print("forward 3x")
> >        time.sleep(2)
> >        stop()
> > ------------------------------------------------------
> 
>  Off-hand, I'd try to get rid of a lot of that redundancy by defining
> functions to encapsulate your sequence... (Python 2.x syntax -- not tested)
> 
> 
> (FORWARD, BACKWARD, LEFT, RIGHT) = (1, 2, 3, 4)
> SEQUENCE = [ (BACKWARD, 2),
>     (RIGHT, 1),
>     (FORWARD, 3),
>     (LEFT, 1),
>     (FORWARD, 2) ]
> 
> def move(drct, dly):
>  if drct == FORWARD:
>   fwd()
>   print "Forward"
>  elif drct == BACKWARD:
>   bwd()
>   print "Backward"
>  elif drct == LEFT:
>   left()
>   print "Left"
>  elif drct == RIGHT:
>   right()
>   print "Right"
>  else:
>   print "Invalid command: %s" % drct
>  time.sleep(dly)
>  stop()
> 
> notDone = True
> servo(90)
> mindist = 80
> 
> while notDone:
>  if mindist > us_dist(15):
>   for (dir, tm) in SEQUENCE:
>    move(dir, tm)
> 
> -=-=-=-=-
> 
>  Now, if you don't mind having to also press the <enter> key, you could
> use the threading module to handle the keyboard shutdown command instead of
> using system specific modules to do raw keystroke input. You'd add
> something before the while loop (and this is really pseudo-code, barely any
> attempt at Python):
> 
> import threading
> 
> def cmdHandler():
>  global notDone
>  while True:
>   cmd = raw_input("Enter command> ").lower()
>   if cmd.startswith("s"):
>    notDone = False
>    break
>   else:
>    print "Unimplemented command: %s" % cmd
> 
> cmdThread = threading.Thread(target=cmdHandler)
> cmdThread.start()
> 
>  This concept doesn't require changes if the underlying OS changes, and
> does open things up to having more complex commands (one could have
> commands with arguments since the input is line oriented).
>  
> --
>  Wulfraed                 Dennis Lee Bieber         AF6VN
>     wlfraed at ix.netcom.com    HTTP://wlfraed.home.netcom.com/




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From avinash3003 at yahoo.co.in  Fri Nov  6 00:30:08 2015
From: avinash3003 at yahoo.co.in (avinash ramu)
Date: Thu, 5 Nov 2015 23:30:08 -0600
Subject: RuntimeError: The size of the array returned by func does not
 match the size of y0
In-Reply-To: <3ef62cda-560c-4eb9-87f0-f91a3f4d653b@googlegroups.com>
References: <3ef62cda-560c-4eb9-87f0-f91a3f4d653b@googlegroups.com>
Message-ID: <CAPPnFwE84F=FiOZH8T7qaUmOU1D7P98y7WGrmvUHEAFEc=DFaQ@mail.gmail.com>

Hi,
The number of elements returned by the function f() needs to match the
number of elements in the initial condition y0.

The problem seems to be in this part of the code,

```
for j in range(0,3*N/2+3):
            return ydot[j]
```

It is returning the first element instead of the list.  I modified your
code to use a temporary list(ydot_new), I then add elements to this new
list using the `for` statement and return the list. This seems to work
fine!  See below,

    79         ydot_new = []
    80         for j in range(0,3*N/2+3):
    81             ydot_new.extend(ydot[j])
    82         return ydot_new

(I'm not an expert on ODE, so I'm not sure how to verify the correctness!)
Cheers,
Avi


On Thu, Nov 5, 2015 at 9:54 PM, Abhishek <abhishek.mallela at gmail.com> wrote:

> I have recently switched from programming heavily in MATLAB to programming
> in Python. Hence I am having some issues running the Python code that I
> have written. I am using IPython with Anaconda2 on Windows 7 and using
> numPy and SciPy to integrate a system of ordinary differential equations. I
> have generalized the system of ODEs for any number 'N' of them.
>
> I have two versions of code that do the same thing, and give the same
> error message. One version uses 'exec' and 'eval' heavily, and the other
> uses arrays heavily. Here is my code for the array version:
>
> ----------------------------------------------------------------------
> import numpy as np
> import matplotlib.pyplot as plt
> from scipy.integrate import odeint
>
> #Constants and parameters
> N = 2
> K00 = np.logspace(0,3,101,10)
> len1 = len(K00)
> epsilon = 0.01
> y0 = [0]*(3*N/2+3)
> u1 = 0
> u2 = 0
> u3 = 0
> Kplot = np.zeros((len1,1))
> Pplot = np.zeros((len1,1))
> S = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
> KS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
> PS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
> Splot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
> KSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
> PSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
>
> for series in range(0,len1):
>     K0 = K00[series]
>     Q = 10
>     r1 = 0.0001
>     r2 = 0.001
>     a = 0.001
>     d = 0.001
>     k = 0.999
>     S10 = 1e5
>     P0 = 1
>     tfvec = np.tile(1e10,(1,5))
>     tf = tfvec[0,0]
>     time = np.linspace(0,tf,len1)
>
>     #Defining dy/dt's
>     def f(y,t):
>         for alpha in range(0,(N/2+1)):
>             S[alpha] = y[alpha]
>         for beta in range((N/2)+1,N+1):
>             KS[beta-N/2-1] = y[beta]
>         for gamma in range(N+1,3*N/2+1):
>             PS[gamma-N] = y[gamma]
>         K = y[3*N/2+1]
>         P = y[3*N/2+2]
>
>         # The model equations
>         ydot = np.zeros((3*N/2+3,1))
>         B = range((N/2)+1,N+1)
>         G = range(N+1,3*N/2+1)
>         runsumPS = 0
>         runsum1 = 0
>         runsumKS = 0
>         runsum2 = 0
>
>         for m in range(0,N/2):
>             runsumPS = runsumPS + PS[m+1]
>             runsum1 = runsum1 + S[m+1]
>             runsumKS = runsumKS + KS[m]
>             runsum2 = runsum2 + S[m]
>             ydot[B[m]] = a*K*S[m]-(d+k+r1)*KS[m]
>
>         for i in range(0,N/2-1):
>             ydot[G[i]] = a*P*S[i+1]-(d+k+r1)*PS[i+1]
>
>         for p in range(1,N/2):
>             ydot[p] = -S[p]*(r1+a*K+a*P)+k*KS[p-1]+ \
>                       d*(PS[p]+KS[p])
>
>         ydot[0] = Q-(r1+a*K)*S[0]+d*KS[0]+k*runsumPS
>         ydot[N/2] = k*KS[N/2-1]-(r2+a*P)*S[N/2]+ \
>                     d*PS[N/2]
>         ydot[G[N/2-1]] = a*P*S[N/2]-(d+k+r2)*PS[N/2]
>         ydot[3*N/2+1] = (d+k+r1)*runsumKS-a*K*runsum2
>         ydot[3*N/2+2] = (d+k+r1)*(runsumPS-PS[N/2])- \
>                         a*P*runsum1+(d+k+r2)*PS[N/2]
>
>         for j in range(0,3*N/2+3):
>             return ydot[j]
>
>     # Initial conditions
>     y0[0] = S10
>     for i in range(1,3*N/2+1):
>         y0[i] = 0
>     y0[3*N/2+1] = K0
>     y0[3*N/2+2] = P0
>
>     # Solve the DEs
>     soln = odeint(f,y0,time,mxstep = 5000)
>     for alpha in range(0,(N/2+1)):
>         S[alpha] = soln[:,alpha]
>     for beta in range((N/2)+1,N+1):
>         KS[beta-N/2-1] = soln[:,beta]
>     for gamma in range(N+1,3*N/2+1):
>         PS[gamma-N] = soln[:,gamma]
>
>     for alpha in range(0,(N/2+1)):
>         Splot[alpha][series] = soln[len1-1,alpha]
>     for beta in range((N/2)+1,N+1):
>         KSplot[beta-N/2-1][series] = soln[len1-1,beta]
>     for gamma in range(N+1,3*N/2+1):
>         PSplot[gamma-N][series] = soln[len1-1,gamma]
>
>     for alpha in range(0,(N/2+1)):
>         u1 = u1 + Splot[alpha]
>     for beta in range((N/2)+1,N+1):
>         u2 = u2 + KSplot[beta-N/2-1]
>     for gamma in range(N+1,3*N/2+1):
>         u3 = u3 + PSplot[gamma-N]
>
>     K = soln[:,3*N/2+1]
>     P = soln[:,3*N/2+2]
>     Kplot[series] = soln[len1-1,3*N/2+1]
>     Pplot[series] = soln[len1-1,3*N/2+2]
>     utot = u1+u2+u3
>
> #Plot
> plt.plot(np.log10(K00),utot[:,0])
> plt.show()
> ----------------------------------------------------------------------
> ERROR MESSAGE:
> RuntimeError: The size of the array returned by func (1) does not match
> the size of y0 (6).
> ----------------------------------------------------------------------
>
> I am facing a RuntimeError in the ODE integrator step. Please help me
> resolve this. Thanks in advance.
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From dan at tombstonezero.net  Fri Nov  6 00:31:25 2015
From: dan at tombstonezero.net (Dan Sommers)
Date: Fri, 6 Nov 2015 05:31:25 -0000 (UTC)
Subject: What does =?iso-8859-13?B?tGdyZXCh?= stand for?
References: <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
 <n1gdkr$mce$1@reader1.panix.com>
 <mailman.67.1446772690.16136.python-list@python.org>
 <NtKdnfI0w7uxvaHLnZ2dnUU7-cednZ2d@giganews.com>
Message-ID: <n1hdvd$737$1@dont-email.me>

On Thu, 05 Nov 2015 19:36:11 -0800, Larry Hudson wrote:

> Anyone besides me remember the CP/M editor Mince (Mince Is Not
> Complete EMACS)?  It was an emacs-like editor, without any e-Lisp or
> other way of extending it.  I believe it was my first exposure to a
> screen-oriented editor.  I quite liked it at that time (but that was a
> looonnng time ago!)

I remember CP/M, but not Mince.  Some of the CP/M boxes I used came with
editors tied to their specific video boards; otherwise, it was ed (which
I'm sure was based on the Unix command of the same name) or MicroPro
WordMaster.

Around that same time frame was Programma Improved Editor on an
Apple?II.  (Apple PIE.  Get it?)

old'ly yours,
Dan


From srinath.nathan at gmail.com  Fri Nov  6 01:13:09 2015
From: srinath.nathan at gmail.com (srinath.nathan at gmail.com)
Date: Thu, 5 Nov 2015 22:13:09 -0800 (PST)
Subject: Python dashboard tutorials/frameworks for interactive, D3.js
 graphs in IPython Notebooks
In-Reply-To: <d2108def-63f8-4719-a06e-afb8775ff107@googlegroups.com>
References: <d2108def-63f8-4719-a06e-afb8775ff107@googlegroups.com>
Message-ID: <907b76a1-5c28-471e-b9c4-fc66ac281184@googlegroups.com>

On Thursday, July 9, 2015 at 8:10:16 PM UTC-4, Matt Sundquist wrote:
> Hi all,
> 
> I'm part of Plotly, and we've just finished a few releases I thought I'd pass along. 
> 
> These tools make it easy to craft interactive graphs and dashboards with D3.js using Python. We're especially drawn towards matplotlib, pandas, and IPython. We're still early in building, so any and all feedback and help is much appreciated.
> 
> First, here is an overview of some of our dashboard capabilities:
> 
> http://blog.plot.ly/post/123617968702/online-dashboards-eight-helpful-tips-you-should
> 
> For more background, refer to our Python docs: https://plot.ly/python/, our Python framework for making dashboards: https://github.com/plotly/dash, our data science blog: http://moderndata.plot.ly/, or these 21 IPython Notebooks: https://plot.ly/python/ipython-notebooks/.
> 
> Feedback and suggestions are welcome!
> 
> M

You guys are so expensive - not even worth looking into your product. Absolutely retarded.
Srinath


From zbin1986 at gmail.com  Fri Nov  6 01:34:50 2015
From: zbin1986 at gmail.com (zbin1986 at gmail.com)
Date: Thu, 5 Nov 2015 22:34:50 -0800 (PST)
Subject: Script to extract text from PDF files
In-Reply-To: <fdbh95$smc$1@solaris.cc.vt.edu>
References: <fdbh95$smc$1@solaris.cc.vt.edu>
Message-ID: <2710bad0-39f0-45f3-afbb-dc98016cb6d5@googlegroups.com>

you can try this free online pdf text extractor http://www.online-code.net/pdf-to-word.html to extract text from pdf free online.


From zbin1986 at gmail.com  Fri Nov  6 02:08:15 2015
From: zbin1986 at gmail.com (zbin1986 at gmail.com)
Date: Thu, 5 Nov 2015 23:08:15 -0800 (PST)
Subject: Using python to convert PDF document to MSWord documents
In-Reply-To: <mailman.4018.1096389067.5135.python-list@python.org>
References: <20040928161317.88987.qmail@web8401.mail.in.yahoo.com>
 <mailman.4018.1096389067.5135.python-list@python.org>
Message-ID: <f340c65e-1d5d-4b6e-b17c-b657c4207696@googlegroups.com>

I'm not a developer, i always use this free online pdf to word converter http://www.online-code.net/pdf-to-word.html to convert pdf to ms doc online.


From rosuav at gmail.com  Fri Nov  6 03:38:11 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 6 Nov 2015 19:38:11 +1100
Subject: Python dashboard tutorials/frameworks for interactive, D3.js
 graphs in IPython Notebooks
In-Reply-To: <907b76a1-5c28-471e-b9c4-fc66ac281184@googlegroups.com>
References: <d2108def-63f8-4719-a06e-afb8775ff107@googlegroups.com>
 <907b76a1-5c28-471e-b9c4-fc66ac281184@googlegroups.com>
Message-ID: <CAPTjJmrqz79QNCifQhihYY+8T4RFNxefT6c2Vy3GRThw6jaGRw@mail.gmail.com>

On Fri, Nov 6, 2015 at 5:13 PM,  <srinath.nathan at gmail.com> wrote:
> On Thursday, July 9, 2015 at 8:10:16 PM UTC-4, Matt Sundquist wrote:
>> For more background, refer to our Python docs: https://plot.ly/python/, our Python framework for making dashboards: https://github.com/plotly/dash, our data science blog: http://moderndata.plot.ly/, or these 21 IPython Notebooks: https://plot.ly/python/ipython-notebooks/.
>>
>
> You guys are so expensive - not even worth looking into your product. Absolutely retarded.
> Srinath

No need to be so rude as you complain about people getting paid for their work.

I'm not even sure your complaint is accurate; where did you see
ridiculously high prices? I started with the first link I quoted above
(the Python docs), and up the top is this note: "plotly is free for
unlimited public use". Then there's a zero-dollar option (though that
might be the same as the previous note), and a $20/mo option called
"professional". If professional usage is only $20 per month, I don't
think it's fair to call it "absolutely retarded". Yes, there's also an
on-premise option for ten grand a year, but that's some serious
top-end privacy stuff... if you think you have to pay that just to
make use of their services, then yes, I can see that you'd complain
about the pricing!

Or was this a deliberate troll to make people go look at the pricing
in more detail?

ChrisA


From amit.ramon at gmail.com  Fri Nov  6 05:07:43 2015
From: amit.ramon at gmail.com (Amit Ramon)
Date: Fri, 6 Nov 2015 12:07:43 +0200
Subject: argparse: use of double dash to separate options and positional
 arguments
Message-ID: <20151106100743.GN3685@isis.luna>

Hello,

I'm trying to use argparse in a program that gets some options and
positional arguments. I want to collect all the positional arguments
in a single argument using the REMAINDER option to add_argument() as
shown bellow:

    parser = argparse.ArgumentParser(description='Test argparse')
    parser.add_argument('-v', '--verbose', action='store_true')
    parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
    print parser.parse_args()

This works well unless the first positional argument starts with a
'-'.

For example, with the above code

    my_prog -v hello world

works well, but

    my_prog -v -x hello world

Fails with an error message 'error: unrecognized arguments: -x'.

If I invoke the program with a '--' at the end of the options (as I
understand is a common standard and a POSIX recommendation), as in:

    my_prog -v -- -x hello world

It works well again.

However, a few questions remain:

Firstly, as far as I can tell the use of '--' is not documented in the
argparse documentation (but the code of argparse clearly shows that it
is a feature).

Secondly, when using '--', this string itself is inserted into the
list of the collected positional arguments (in the above example in
the cmd_args variable):

$ ./my_prog -v -- -x hello world
Namespace(cmd_args=['--', '-x', 'hello', 'world'], verbose=True)

It's quiet easy to check for it and remove it if it exists, but it
still seems like it shouldn't be there - it is not really an argument,
just a delimiter.

Am I doing anything wrong, or is this a bug? I hope someone here can
shed some light on this.

Thanks,

Amit



-- 


From rosuav at gmail.com  Fri Nov  6 05:30:16 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 6 Nov 2015 21:30:16 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <201511061033583772468@travelsky.com>
References: <201511061033583772468@travelsky.com>
Message-ID: <CAPTjJmr7brs6B=oD9m2bEk_Mm7wUTVKWU-gxqgAqDLV4diOdzw@mail.gmail.com>

On Fri, Nov 6, 2015 at 1:33 PM, wangq at travelsky.com <wangq at travelsky.com> wrote:
> Hello, python-list guys:
>
>     I am a newbie of python from Beijing. China.
>     I have a question about "math.pi".
>     As you can see in the attachment, why i can modify "math.pi"?
>     (in "mathmodule.c" "pi" is a "static const double")
>
> Thank you in advance!
>
> Best Wishes?

Simply because, in Python, virtually everything can be changed. You're
welcome to go in and say "math.pi = 3" if you like... and then you
accept the consequences of that.

There are times when you want to change these sorts of 'constants'.
For example, math.pi is a float; but if you're working with
decimal.Decimal everywhere, it might be useful to replace it with a
corresponding Decimal value:

math.pi = decimal.Decimal("3.14159265358979323")

And that's perfectly legal.

ChrisA


From rosuav at gmail.com  Fri Nov  6 05:34:00 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 6 Nov 2015 21:34:00 +1100
Subject: Olivier Adret
In-Reply-To: <563B74B6.80402@gmail.com>
References: <563B74B6.80402@gmail.com>
Message-ID: <CAPTjJmriGNTidHNySNrjXCs8kdbhYWZb96DwmXwfs+s_p5_LsA@mail.gmail.com>

On Fri, Nov 6, 2015 at 2:24 AM, olivier <olivier.adret02 at gmail.com> wrote:
>      Je vais essayer de programmer en python. On verra bien !

Hello Olivier!

This is a mostly English language mailing list/newsgroup, and there
aren't many people who are fluent in French. There is, however, a
corresponding French newsgroup, fr.comp.lang.python; you may find that
you're more comfortable communicating there.

My apologies for not responding in French, but I'm not very familiar
with it, and all I would do is put my text through an online
translation tool.

Chris Angelico


From ian.g.kelly at gmail.com  Fri Nov  6 05:38:10 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 6 Nov 2015 03:38:10 -0700
Subject: Question about math.pi is mutable
In-Reply-To: <201511061033583772468@travelsky.com>
References: <201511061033583772468@travelsky.com>
Message-ID: <CALwzid=opt0qM87P+MEH6VY+BxcaRtrM1vQJyv8jBkV9YpUMDA@mail.gmail.com>

On Nov 6, 2015 3:20 AM, "wangq at travelsky.com" <wangq at travelsky.com> wrote:
>
> Hello, python-list guys:
>
>     I am a newbie of python from Beijing. China.
>     I have a question about "math.pi".
>     As you can see in the attachment, why i can modify "math.pi"?
>     (in "mathmodule.c" "pi" is a "static const double")

Like all floats, math.pi is immutable. However, the *name* pi in the math
module is not special and can be rebound to a new value, like (almost) any
other name.

So yes, you can assign 3 to math.pi. You can also assign 3 to math.sqrt, or
os.urandom, or float.


From __peter__ at web.de  Fri Nov  6 05:57:06 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 06 Nov 2015 11:57:06 +0100
Subject: argparse: use of double dash to separate options and positional
 arguments
References: <20151106100743.GN3685@isis.luna>
Message-ID: <n1i126$o2f$1@ger.gmane.org>

Amit Ramon wrote:

> Hello,
> 
> I'm trying to use argparse in a program that gets some options and
> positional arguments. I want to collect all the positional arguments
> in a single argument using the REMAINDER option to add_argument() as
> shown bellow:
> 
>     parser = argparse.ArgumentParser(description='Test argparse')
>     parser.add_argument('-v', '--verbose', action='store_true')
>     parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
>     print parser.parse_args()
> 
> This works well unless the first positional argument starts with a
> '-'.
> 
> For example, with the above code
> 
>     my_prog -v hello world
> 
> works well, but
> 
>     my_prog -v -x hello world
> 
> Fails with an error message 'error: unrecognized arguments: -x'.

This looks like a bug to me. Please report it on bug.python.org.
 
> If I invoke the program with a '--' at the end of the options (as I
> understand is a common standard and a POSIX recommendation), as in:
> 
>     my_prog -v -- -x hello world
> 
> It works well again.
> 
> However, a few questions remain:
> 
> Firstly, as far as I can tell the use of '--' is not documented in the
> argparse documentation (but the code of argparse clearly shows that it
> is a feature).
> 
> Secondly, when using '--', this string itself is inserted into the
> list of the collected positional arguments (in the above example in
> the cmd_args variable):
> 
> $ ./my_prog -v -- -x hello world
> Namespace(cmd_args=['--', '-x', 'hello', 'world'], verbose=True)
> 
> It's quiet easy to check for it and remove it if it exists, but it
> still seems like it shouldn't be there - it is not really an argument,
> just a delimiter.

I'm not sure about this one; one purpose of REMAINDER is to pass on the 
unprocessed arguments to another program/script, and this might follow the 
same convention. Should

parser.add_argument('-v', '--verbose', action='store_true')
parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
args = parser.parse_args()
subprocess.call(["rm"] + args.cmd_args)

$ my_prog -v -- -r foo

attempt to delete two files "-r" and "foo" or remove the "foo" directory? 
The first is the safer alternative, and as you say stripping the "--" is 
easy.


> Am I doing anything wrong, or is this a bug? I hope someone here can
> shed some light on this.




From amit.ramon at gmail.com  Fri Nov  6 06:44:59 2015
From: amit.ramon at gmail.com (Amit Ramon)
Date: Fri, 6 Nov 2015 13:44:59 +0200
Subject: argparse: use of double dash to separate options and positional
 arguments
In-Reply-To: <n1i126$o2f$1@ger.gmane.org>
References: <20151106100743.GN3685@isis.luna>
 <n1i126$o2f$1@ger.gmane.org>
Message-ID: <20151106114459.GO3685@isis.luna>

Peter Otten <__peter__ at web.de> [2015-11-06 11:57 +0100]:


>>
>> For example, with the above code
>>
>>     my_prog -v hello world
>>
>> works well, but
>>
>>     my_prog -v -x hello world
>>
>> Fails with an error message 'error: unrecognized arguments: -x'.
>
>This looks like a bug to me. Please report it on bug.python.org.

Why does it looks like a bug? To me it seems okay - argparse expects
that an argument that starts with '-' is an option, and it also expects
to be told about all possible options, so it complains on
encountering an unrecognized 'option'. This is why a special delimiter
is needed to mark the 'end of options'.


>
>> If I invoke the program with a '--' at the end of the options (as I
>> understand is a common standard and a POSIX recommendation), as in:
>>
>>     my_prog -v -- -x hello world
>>
>> It works well again.
>>
>> However, a few questions remain:
>>
>> Firstly, as far as I can tell the use of '--' is not documented in the
>> argparse documentation (but the code of argparse clearly shows that it
>> is a feature).
>>
>> Secondly, when using '--', this string itself is inserted into the
>> list of the collected positional arguments (in the above example in
>> the cmd_args variable):
>>
>> $ ./my_prog -v -- -x hello world
>> Namespace(cmd_args=['--', '-x', 'hello', 'world'], verbose=True)
>>
>> It's quiet easy to check for it and remove it if it exists, but it
>> still seems like it shouldn't be there - it is not really an argument,
>> just a delimiter.
>
>I'm not sure about this one; one purpose of REMAINDER is to pass on the
>unprocessed arguments to another program/script, and this might follow the
>same convention. Should
>
>parser.add_argument('-v', '--verbose', action='store_true')
>parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
>args = parser.parse_args()
>subprocess.call(["rm"] + args.cmd_args)
>
>$ my_prog -v -- -r foo
>
>attempt to delete two files "-r" and "foo" or remove the "foo" directory?
>The first is the safer alternative, and as you say stripping the "--" is
>easy.

I'm using the REMAINDER exactly for passing on arguments to another
program, as in your example. I would expect that everything after
the '--' should be passed on as is - it should be up to the other
program to decide what to do with the arguments it receives (So in
your examples, rm would actually try to remove the "foo" directory).

And although stripping the '--' is easy, why should the user of
argparse need to handle it? Still unclear to me.

Cheers,

Amit


From input/ldompeling at casema.nl  Fri Nov  6 06:50:50 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Fri, 06 Nov 2015 11:50:50 GMT
Subject: raw_input and break
References: <LBW_x.37419$pB.28644@fe37.am1>
Message-ID: <uu0%x.51136$Mw6.36660@fx03.am1>

Hi,

I tried to define SEQUENCE with:
The script is working now, exept that I do'nt get a menu in terminal for "s" to stop.
---------------------------------------------------------------------------------

def SEQUENCE():


    while notDone:
        if mindist > us_dist(15):
            for (dir, tm) in SEQUENCE:
                    move(dir, tm)

---------------------------------------------------------------------------------
In reply to "input/ldompeling at casema.nl" who wrote the following:

> He,
> Thank you for making some time for it.
> Is this your code ?
> I am also using python 3
> 
> I got an error with execute the scipt:
> -----------------------------------------------------------------------
> 
> Enter command> Traceback (most recent call last):
>   File "test06.py", line 44, in <module>
>     for (dir, tm) in SEQUENCE:
> NameError: name 'SEQUENCE' is not defined
> -----------------------------------------------------------------------
> 
> import time
> import threading
> 
> set_right_speed(150)
> set_left_speed(105)
> 
> def cmdHandler():
>         global notDone
>         while True:
>                 cmd = raw_input("Enter command> ").lower()
>                 if cmd.startswith("s"):
>                         notDone = False
>                         break
>                 else:
>                         print ("Unimplemented command: %s") % cmd
> 
> cmdThread = threading.Thread(target=cmdHandler)
> cmdThread.start()
> def move(drct, dly):
>         if drct == FORWARD:
>                 fwd()
>                 print ("Forward")
>         elif drct == BACKWARD:
>                 bwd()
>                 print ("Backward")
>         elif drct == LEFT:
>                 left()
>                 print ("Left")
>         elif drct == RIGHT:
>                 right()
>                 print ("Right")
>         else:
>                 print ("Invalid command: %s") % drct
>         time.sleep(dly)
>         stop()
> 
> notDone = True
> 
> servo(90)
> mindist = 80
> 
> while notDone:
>         if mindist > us_dist(15):
>                 for (dir, tm) in SEQUENCE:
>                         move(dir, tm)
> 
> ------------------------------------------------------------------------------
> ---------------
> In reply to "Dennis Lee Bieber" who wrote the following:
> 
> > On Thu, 05 Nov 2015 17:28:36 GMT, input/ldompeling at casema.nl declaimed the
> > following:
> > 
> > > Oke, lets try your code.Can you help me with that.
> > > This is my code:
> > > -------------------------------------------------
> > > from gopigo import *
> > > import time
> > > 
> > > set_right_speed(150)
> > > set_left_speed(105)
> > 
> >  Is there a typo there? If those are setting rotation speeds for
> > independent drive wheels, you will have a slow left turn enabled.
> > 
> > > enable_servo()
> > > fwd()
> > > print("forward 1x")
> > > time.sleep(4)
> > > stop()
> > > 
> > > while True:
> > >    servo(90)
> > >    mindist = 80
> > > 
> > >    if mindist > us_dist(15):
> > 
> >  "mindist" will always be 80 -- there is no code shown below that ever
> > changes it (so the above assignment can be put before the "while"
> > statement). That means your us_dist() function must somewhere return a
> > value greater than 80.
> > 
> > >        bwd()
> > >        print ("backward 1x")
> > >        time.sleep(2)
> > >        stop()
> > >        right()
> > >        time.sleep(1)
> > >        stop()
> > >        print("right 1x")
> > >        time.sleep(2)
> > 
> >  You stopped the right() call before ever doing any output
> > 
> > >        stop()
> > >        fwd()
> > >        print("forward 2x")
> > >        time.sleep(3)
> > >        stop()
> > >        left()
> > >        time.sleep(1)
> > >        print("left 1x")
> > >        stop()
> > >        fwd()
> > >        print("forward 3x")
> > >        time.sleep(2)
> > >        stop()
> > > ------------------------------------------------------
> > 
> >  Off-hand, I'd try to get rid of a lot of that redundancy by defining
> > functions to encapsulate your sequence... (Python 2.x syntax -- not tested)
> > 
> > 
> > (FORWARD, BACKWARD, LEFT, RIGHT) = (1, 2, 3, 4)
> > SEQUENCE = [ (BACKWARD, 2),
> >     (RIGHT, 1),
> >     (FORWARD, 3),
> >     (LEFT, 1),
> >     (FORWARD, 2) ]
> > 
> > def move(drct, dly):
> >  if drct == FORWARD:
> >   fwd()
> >   print "Forward"
> >  elif drct == BACKWARD:
> >   bwd()
> >   print "Backward"
> >  elif drct == LEFT:
> >   left()
> >   print "Left"
> >  elif drct == RIGHT:
> >   right()
> >   print "Right"
> >  else:
> >   print "Invalid command: %s" % drct
> >  time.sleep(dly)
> >  stop()
> > 
> > notDone = True
> > servo(90)
> > mindist = 80
> > 
> > while notDone:
> >  if mindist > us_dist(15):
> >   for (dir, tm) in SEQUENCE:
> >    move(dir, tm)
> > 
> > -=-=-=-=-
> > 
> >  Now, if you don't mind having to also press the <enter> key, you could
> > use the threading module to handle the keyboard shutdown command instead of
> > using system specific modules to do raw keystroke input. You'd add
> > something before the while loop (and this is really pseudo-code, barely any
> > attempt at Python):
> > 
> > import threading
> > 
> > def cmdHandler():
> >  global notDone
> >  while True:
> >   cmd = raw_input("Enter command> ").lower()
> >   if cmd.startswith("s"):
> >    notDone = False
> >    break
> >   else:
> >    print "Unimplemented command: %s" % cmd
> > 
> > cmdThread = threading.Thread(target=cmdHandler)
> > cmdThread.start()
> > 
> >  This concept doesn't require changes if the underlying OS changes, and
> > does open things up to having more complex commands (one could have
> > commands with arguments since the input is line oriented).
> > 
> > --
> >  Wulfraed                 Dennis Lee Bieber         AF6VN
> >     wlfraed at ix.netcom.com    HTTP://wlfraed.home.netcom.com/
> 
> 
> 
> 
> --
> --------------------------------- --- -- -
> Posted with NewsLeecher v7.0 Beta 2
> Web @ http://www.newsleecher.com/?usenet
> ------------------- ----- ---- -- -




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From vs at it.uu.se  Fri Nov  6 06:53:43 2015
From: vs at it.uu.se (Virgil Stokes)
Date: Fri, 6 Nov 2015 12:53:43 +0100
Subject: Questions on Pickle and Shelve
Message-ID: <563C94C7.8030805@it.uu.se>

Here is snippet of Python (vers. 2.7.10) code that bothers me.

import cPickle as pickle

print "Pickle lists:"
dogs = ['Rover','King','Spot','Rufus']
cats = ['Mimi','Misty','Sasha']

with open('pickle.dat', 'wb') as pfile:
     pickle.dump(dogs, pfile)
     pickle.dump(cats,pfile)

del(dogs); del(cats)
with open('pickle.dat', 'rb') as pfile:
     dogs = pickle.load(pfile)
     cats = pickle.load(pfile)
     print dogs, '\n', cats, '\n'

import shelve

# Note! __exit__ attribute undefined for shelve
sfile = shelve.open('shelve.dat')
sfile['dogs'] = dogs
sfile['cats'] = cats
sfile.close()

print "Shelve entries:"
del(cats); del(dogs)
sfile = shelve.open('shelve.dat')
#print sfile
for key in sfile.keys():
     print key,' - ',sfile[key]
sfile.close()

1)  Which (the pickle or shelve code) takes less total RAM, if dogs and cats 
were very large?
2)  When the last shelve.open is given, is the entire contents of shelve.data 
transferred to RAM?  Note, if the print sfile is uncommented then the entire 
contents of shelve.data is printed out.

I was under the impression that the entire contents of a shelved file was not 
transferred to RAM when it was opened.




From bc at freeuk.com  Fri Nov  6 07:30:29 2015
From: bc at freeuk.com (Bartc)
Date: Fri, 6 Nov 2015 12:30:29 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.77.1446804678.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
Message-ID: <n1i6d4$bfg$1@dont-email.me>

On 06/11/2015 02:33, wangq at travelsky.com wrote:
> Hello, python-list guys:
>
>      I am a newbie of python from Beijing. China.
>      I have a question about "math.pi".
>      As you can see in the attachment, why i can modify "math.pi"?
>      (in "mathmodule.c" "pi" is a "static const double")

Python isn't C.

Your attachment isn't visible, but it can be demonstrated easily:

import math

math.pi=0

print (math.pi)

In Python, presumably 'pi' is just another variable, and variables can 
be written to.

(Perhaps math.pi would be better off as a function.)

-- 
Bartc



From marko at pacujo.net  Fri Nov  6 07:55:00 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 06 Nov 2015 14:55:00 +0200
Subject: Question about math.pi is mutable
References: <201511061033583772468@travelsky.com>
 <mailman.78.1446805818.16136.python-list@python.org>
Message-ID: <87k2pvi8yj.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> Simply because, in Python, virtually everything can be changed. You're
> welcome to go in and say "math.pi = 3" if you like... and then you
> accept the consequences of that.

How far cosmology would have evolved by now if Albert Einstein had had
Python at his disposal. He could simply have been able to experiment
with different values of the Cosmological Constant and seen the effects
around him in the room.


Marko


From gheskett at wdtv.com  Fri Nov  6 08:21:42 2015
From: gheskett at wdtv.com (Gene Heskett)
Date: Fri, 6 Nov 2015 08:21:42 -0500
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A8D60B8@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511052310.tA5NAjAk026602@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D60B8@DCBL123VX.root.sutterhealth.org>
Message-ID: <201511060821.42877.gheskett@wdtv.com>

On Thursday 05 November 2015 19:04:35 Robinson, Wendy wrote:

> Hmmm... fair enough.  I sent the traceback though, on Monday.

If you sent a traceback on Monday, it wasn't seen by this list.
Do not 'attach' it to the message, but include it as the list server 
might have stripped an attachment.

> I'll give the intro a read again.  I've probably missed something
> basic.
>
> Wendy Robinson
> Audit Analyst
> (916)?566-4994 phone
>
>
>
> NOTICE OF CONFIDENTIALITY: This email is for the sole use of the
> intended recipient and may contain material that is confidential and
> protected by state and federal regulations.? If you are not the
> intended recipient please immediately delete it and contact the
> sender.

This is a public list Wendy, so this has no meaning. There are those, who 
on seeing such a message, will not reply even if they could help.

> -----Original Message-----
> From: Laura Creighton [mailto:lac at openend.se]
> Sent: Thursday, November 05, 2015 3:11 PM
> To: Robinson, Wendy
> Cc: 'Laura Creighton'; 'python-list at python.org'; lac at openend.se
> Subject: Re: Puzzled
>
> In a message of Thu, 05 Nov 2015 12:48:11 -0800, "Robinson, Wendy" 
writes:
> >Well... I still can't get this to work. I guess I'll just uninstall
> > it. It's a bummer that there's no help on basic startup like this.
> >
> >Wendy Robinson
> >Audit Analyst
> >(916)?566-4994 phone
>
> There is enormous amount of help available.  But we need to know more
> about what your problem is, and how it presents itself before we can
> start tracking down what your problem is, which is why I wanted a
> traceback.
>
> >>Hi there,
> >>I installed Python 3.5.0 64-bit for Windows yesterday and tried some
> >> basic programs successfully. This morning I rebooted my computer
> >> and can't get a single one to work.  The interpreter seems to be
> >> fine and the environment variables look correct.  But every py file
> >> I try to run at the >>> prompt gives me a NameError.
>
> See, this is where your problem is. There is a conceptual problem in
> understanding what you meant by 'tried some basic programs
> successfully' versus 'running py files at the >>> prompt'.
>
> Either you didn't use the Python console -- the thing that is showing
> you the '>>>' yesterday, and thus the programs that were working
> yesterday are now working every bit as well as they did then, and your
> problem is that you do not know how to use the python console.
>
> Or you did use the console before, and they worked there, and now you
> have NameErrors.
>
> I think the problem is the first sort.
> I think that you opened up the python console and then typed in
> something like 'myprogram.py' expecting the console to run the
> myprogram.  Instead you got something like this:
>
> Python 3.5.0rc1 (default, Aug 12 2015, 14:57:46) [GCC 5.2.1 20150808]
> on linux Type "help", "copyright", "credits" or "license" for more
> information.
>
>  >>> myprogram.py
>
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> NameError: name 'myprogram' is not defined  >>>
>
> If this is what happened then your python is fine.  You just do not
> know how the interactive console works.  It doesn't run files like
> this.
>
> See:https://docs.python.org/3.5/tutorial/introduction.html
>
> You type code at the console and get responses back.
>
> If, on the other hand, this is not your problem, then we need a
> traceback --- and what I posted above was a traceback -- so that we
> can see what caused the NameError.
>
> Laura


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>


From wrw at mac.com  Fri Nov  6 08:25:09 2015
From: wrw at mac.com (William Ray Wing)
Date: Fri, 06 Nov 2015 08:25:09 -0500
Subject: =?utf-8?Q?Re=3A_What_does_=E2=80=9Cgrep=E2=80=9D_stand_for=3F?=
In-Reply-To: <NtKdnfI0w7uxvaHLnZ2dnUU7-cednZ2d@giganews.com>
References: <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
 <n1gdkr$mce$1@reader1.panix.com>
 <mailman.67.1446772690.16136.python-list@python.org>
 <NtKdnfI0w7uxvaHLnZ2dnUU7-cednZ2d@giganews.com>
Message-ID: <B1E04EC8-72B8-4EBD-8262-41445F91DECB@mac.com>


> On Nov 5, 2015, at 10:36 PM, Larry Hudson via Python-list <python-list at python.org> wrote:
> 
> On 11/05/2015 05:18 PM, Dennis Lee Bieber wrote:
>> On Thu, 5 Nov 2015 20:19:39 +0000 (UTC), Grant Edwards
>> <invalid at invalid.invalid> declaimed the following:
>> 
>>> Though I used a line-editor for a while on VMS, I was never very good
>>> at it, and abanded it for a full-screen editor at he first
>>> opportunity.  But, if you ever get a chance to watching somebody who
>>> _is_ good at 'ed', it's something you'll remember...
>> 
>> 	I didn't convert to EDT until DEC dropped SOS... And then shortly later
>> I keymapped the Blaise ([Alcor] Pascal) editor on the TRS-80 Mod-III to
>> replicate EDT (as much as possible, given only three function keys on the
>> numeric pad)
>> 
>> 	The Amiga used to have two standard editors -- a screen editor and a
>> line editor; as I recall the line editor supported a file window, so one
>> could edit large files by making a single direction pass using a smaller
>> window and a script. Later the screen editor gained ARexx support, so one
>> could script it using ARexx. (And by then they also included a form of
>> microEMACS, my C compiler had a look-alike vi editor... and a later C
>> compiler had another editor integrated to the compiler so that error
>> message reports could trigger the editor to open the file and move to the
>> error position)
>> 
> Anyone besides me remember the CP/M editor Mince (Mince Is Not Complete EMACS)?
> It was an emacs-like editor, without any e-Lisp or other way of extending it.  I believe it was my first exposure to a screen-oriented editor.  I quite liked it at that time (but that was a looonnng time ago!)
> 
>     -=- Larry -=-
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list

You?re not REALLY an old timer unless you?ve used TECO.

-Bill



From mr.eightnoteight at gmail.com  Fri Nov  6 08:40:07 2015
From: mr.eightnoteight at gmail.com (srinivas devaki)
Date: Fri, 6 Nov 2015 19:10:07 +0530
Subject: Unbuffered stderr in Python 3
In-Reply-To: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
References: <5637165b$0$1505$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CACs7g=B7vgrPqVzhTrj3zTSbiyBzb2zLOW51uGUh4w6r5iatUg@mail.gmail.com>

On Mon, Nov 2, 2015 at 1:22 PM, Steven D'Aprano
<steve+comp.lang.python at pearwood.info> wrote:
>
> So how come Python 3 has line buffered stderr? And more importantly, how can
> I turn buffering off?
>
> I don't want to use the -u unbuffered command line switch, because that
> effects stdout as well. I'm happy for stdout to remain buffered.
>
you can simply turn buffering off for stderr by redefining the print
function or declaring a new print function like


from functools import partial
print = partial(print, flush=True)
# or
from functools import partial
import sys
printerr = partial(print, flush=True, file=sys.stderr)


From chris at gonnerman.org  Fri Nov  6 08:40:29 2015
From: chris at gonnerman.org (Chris Gonnerman)
Date: Fri, 6 Nov 2015 07:40:29 -0600
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
Message-ID: <563CADCD.8070307@gonnerman.org>

Wendy said:
> I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
> This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.
But that's not how the Python interpreter works.  You say you are trying 
to run "py files" at the >>> prompt.  If what you are doing is this:

     >>> test.py

Well, no, that's not going to work.  If you want to run "test.py" as a 
script, from the CMD prompt you type:

     python test.py

If test.py is a module meant to be imported, then from the Python prompt 
you do this:

     import test

Hope this helps.

-- Chris.



From invalid at invalid.invalid  Fri Nov  6 09:15:43 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 6 Nov 2015 14:15:43 +0000 (UTC)
Subject: What does ???grep??? stand for?
References: <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
 <n1gdkr$mce$1@reader1.panix.com>
 <mailman.67.1446772690.16136.python-list@python.org>
Message-ID: <n1icmf$54g$1@reader1.panix.com>

On 2015-11-06, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Thu, 5 Nov 2015 20:19:39 +0000 (UTC), Grant Edwards
><invalid at invalid.invalid> declaimed the following:
>
>>Though I used a line-editor for a while on VMS, I was never very good
>>at it, and abanded it for a full-screen editor at he first
>>opportunity.  But, if you ever get a chance to watching somebody who
>>_is_ good at 'ed', it's something you'll remember...
>
> 	I didn't convert to EDT until DEC dropped SOS...

Yes! Son of Stopgap!  I had completely forgotten the name...  And then
I think Eve came after EDT.  That was about where I switched to Unix.

--
Grant



From __peter__ at web.de  Fri Nov  6 10:13:11 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 06 Nov 2015 16:13:11 +0100
Subject: argparse: use of double dash to separate options and positional
 arguments
References: <20151106100743.GN3685@isis.luna> <n1i126$o2f$1@ger.gmane.org>
 <20151106114459.GO3685@isis.luna>
Message-ID: <n1ig29$jjt$1@ger.gmane.org>

Amit Ramon wrote:

> Peter Otten <__peter__ at web.de> [2015-11-06 11:57 +0100]:
> 
> 
>>>
>>> For example, with the above code
>>>
>>>     my_prog -v hello world
>>>
>>> works well, but
>>>
>>>     my_prog -v -x hello world
>>>
>>> Fails with an error message 'error: unrecognized arguments: -x'.
>>
>>This looks like a bug to me. Please report it on bug.python.org.
> 
> Why does it looks like a bug? To me it seems okay - argparse expects
> that an argument that starts with '-' is an option, and it also expects
> to be told about all possible options, so it complains on
> encountering an unrecognized 'option'. This is why a special delimiter
> is needed to mark the 'end of options'.
> 
> 
>>
>>> If I invoke the program with a '--' at the end of the options (as I
>>> understand is a common standard and a POSIX recommendation), as in:
>>>
>>>     my_prog -v -- -x hello world
>>>
>>> It works well again.
>>>
>>> However, a few questions remain:
>>>
>>> Firstly, as far as I can tell the use of '--' is not documented in the
>>> argparse documentation (but the code of argparse clearly shows that it
>>> is a feature).
>>>
>>> Secondly, when using '--', this string itself is inserted into the
>>> list of the collected positional arguments (in the above example in
>>> the cmd_args variable):
>>>
>>> $ ./my_prog -v -- -x hello world
>>> Namespace(cmd_args=['--', '-x', 'hello', 'world'], verbose=True)
>>>
>>> It's quiet easy to check for it and remove it if it exists, but it
>>> still seems like it shouldn't be there - it is not really an argument,
>>> just a delimiter.
>>
>>I'm not sure about this one; one purpose of REMAINDER is to pass on the
>>unprocessed arguments to another program/script, and this might follow the
>>same convention. Should
>>
>>parser.add_argument('-v', '--verbose', action='store_true')
>>parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
>>args = parser.parse_args()
>>subprocess.call(["rm"] + args.cmd_args)
>>
>>$ my_prog -v -- -r foo
>>
>>attempt to delete two files "-r" and "foo" or remove the "foo" directory?
>>The first is the safer alternative, and as you say stripping the "--" is
>>easy.
> 
> I'm using the REMAINDER exactly for passing on arguments to another
> program, as in your example. I would expect that everything after
> the '--' should be passed on as is - it should be up to the other
> program to decide what to do with the arguments it receives (So in
> your examples, rm would actually try to remove the "foo" directory).
> 
> And although stripping the '--' is easy, why should the user of
> argparse need to handle it? Still unclear to me.

My interpretation was that REMAINDER should give you the rest of the 
commandline args, no matter what special meaning these args might have for 
argparse.



From courseforum at gmail.com  Fri Nov  6 10:45:54 2015
From: courseforum at gmail.com (Mark Roseman)
Date: Fri, 6 Nov 2015 07:45:54 -0800 (PST)
Subject: Modernizing IDLE
Message-ID: <0c616344-06ab-43ed-a570-79c60aa41137@googlegroups.com>

Wanted to pass along a case study of some work being done to improve the look and feel of IDLE. This is a work-in-progress, gradually being integrated into the Python codebase. Given that, it's a great opportunity to get involved, provide some feedback, and make it even better!

    http://www.tkdocs.com/tutorial/idle.html

As you can tell from the URL, it's part of a broader tutorial on modernizing the appearance of Tkinter based programs.

Mark


From lorenzofsutton at gmail.com  Fri Nov  6 11:12:07 2015
From: lorenzofsutton at gmail.com (Lorenzo Sutton)
Date: Fri, 6 Nov 2015 17:12:07 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <n1i6d4$bfg$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
Message-ID: <563CD157.7060105@gmail.com>



On 06/11/2015 13:30, Bartc wrote:
> On 06/11/2015 02:33, wangq at travelsky.com wrote:
>> Hello, python-list guys:
>>
>>      I am a newbie of python from Beijing. China.
>>      I have a question about "math.pi".
>>      As you can see in the attachment, why i can modify "math.pi"?
>>      (in "mathmodule.c" "pi" is a "static const double")
>
> Python isn't C.
>
> Your attachment isn't visible, but it can be demonstrated easily:
>
> import math
>
> math.pi=0
>
> print (math.pi)
>
> In Python, presumably 'pi' is just another variable, and variables can
> be written to.
>
> (Perhaps math.pi would be better off as a function.)

Still nothing stops you from doing:

math.sin = 0

If you really want to?


From kwpolska at gmail.com  Fri Nov  6 11:43:17 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Fri, 6 Nov 2015 17:43:17 +0100
Subject: Questions on Pickle and Shelve
In-Reply-To: <563C94C7.8030805@it.uu.se>
References: <563C94C7.8030805@it.uu.se>
Message-ID: <CAMw+j7+YKVvbt7xswjbBgU9qvGciZnUPXD6NnifTvJx7H7knZg@mail.gmail.com>

On 6 November 2015 at 12:53, Virgil Stokes <vs at it.uu.se> wrote:
> Here is snippet of Python (vers. 2.7.10) code that bothers me.
>
> [snip bad code]
>
> 1)  Which (the pickle or shelve code) takes less total RAM, if dogs and cats
> were very large?
> 2)  When the last shelve.open is given, is the entire contents of
> shelve.data transferred to RAM?  Note, if the print sfile is uncommented
> then the entire contents of shelve.data is printed out.
>
> I was under the impression that the entire contents of a shelved file was
> not transferred to RAM when it was opened.
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list

1) That does not matter. I do know that shelve files can grow larger
over time though.
2) Shelve files are pickles in disguise. Which means they need to be
loaded into memory, executing *arbitrary code*.

Here?s a question for you:
3) Why are you using either? Both are unsafe and can lead to issues if
you take untrusted files. Use JSON.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From __peter__ at web.de  Fri Nov  6 13:15:56 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 06 Nov 2015 19:15:56 +0100
Subject: Questions on Pickle and Shelve
References: <563C94C7.8030805@it.uu.se>
Message-ID: <n1iqp5$d6u$1@ger.gmane.org>

Virgil Stokes wrote:

> Here is snippet of Python (vers. 2.7.10) code that bothers me.
> 
> import cPickle as pickle
> 
> print "Pickle lists:"
> dogs = ['Rover','King','Spot','Rufus']
> cats = ['Mimi','Misty','Sasha']
> 
> with open('pickle.dat', 'wb') as pfile:
>      pickle.dump(dogs, pfile)
>      pickle.dump(cats,pfile)
> 
> del(dogs); del(cats)
> with open('pickle.dat', 'rb') as pfile:
>      dogs = pickle.load(pfile)
>      cats = pickle.load(pfile)
>      print dogs, '\n', cats, '\n'
> 
> import shelve
> 
> # Note! __exit__ attribute undefined for shelve
> sfile = shelve.open('shelve.dat')
> sfile['dogs'] = dogs
> sfile['cats'] = cats
> sfile.close()
> 
> print "Shelve entries:"
> del(cats); del(dogs)
> sfile = shelve.open('shelve.dat')
> #print sfile
> for key in sfile.keys():
>      print key,' - ',sfile[key]
> sfile.close()
> 
> 1)  Which (the pickle or shelve code) takes less total RAM, if dogs and
> cats were very large?

I think this is the wrong question. shelve is built on top of a key-value 
store. It can hold more cats and dogs than fit into memory, and lookup of a 
cat or dog should be efficient when you store one animal per key:

db = shelve.open(...)
db["Rover"] = Dog(...)
db["King"] =  Dog(...)
db["Misty"] = Cat(...)

If you put all dogs in a big list to store them in the shelve and there are 
only a few such lists there is no advantage over plain pickle.

> 2)  When the last shelve.open is given, is the entire contents of
> shelve.data
> transferred to RAM?  Note, if the print sfile is uncommented then the
> entire contents of shelve.data is printed out.

That is due to a careless implementation. Lookup is good, but everything 
else will only work for debugging, with small data samples.

> I was under the impression that the entire contents of a shelved file was
> not transferred to RAM when it was opened.

They aren't. The details vary depending on what database is used.



From D.Strohl at F5.com  Fri Nov  6 13:21:23 2015
From: D.Strohl at F5.com (Dan Strohl)
Date: Fri, 6 Nov 2015 18:21:23 +0000
Subject: python PEP suggestion
Message-ID: <cf746bff3459405cbdf04acabce99cae@seaexchmbx03.olympus.F5Net.com>

All,

I wanted to run the following thought past the list as a possible PEP enhancement suggestion to see if it feels like something that is worth proposing.   I know it is not in the PEP format at this point, I can, and will, clean it up if needed, I am just trying to throw it against the wall at this point to see if it resonates... (or if it falls flat and goes "splat" <grin>).

Thoughts?

Dan Strohl



New special method name to allow for more flexible object type casting/access, and extend type() to cast objects using this special method name.

Overview:

Have a new special method name that would allow a given objects to request information from another object in a given type, or to cast an object into a different type, and extend the built in type() function to use this.

Rationale:
There is currently __str__, __int__, and __bool__ that allow me to tell an object how it should reply to a request for these types of basic data types.  However if I want to access a copy of the objet in dict form, or as a list, or if I am trying to convert something using json, there is no standard way of doing that for a custom object (I know I can do __getitem__ and/or __iter__, but I many processes don't try these if the object is not a subclass of dict or list/tuple)

Proposal:
What I am proposing is something like:

object.__cast__(self, to_class):
                              """
                              to_class: the class type that you wish to return.
                              """

               -and-

               Class type(object, to_class):
                              """
                              With two arguments, will attempt to cast "object" into "to_class" if possible.   This would be done by something like the following:
                              (with 1 and 3 arguments, will work as currently designed)
                              """
                              Type(object, to_class):
                                             If isinstance(to_class, (int, str, bool)):
                                                            Return to_class(object)
                                             Else:
                                                            Try:
                                                                           Return object.__cast__(to_class):
                                                            Except AttributeError:
                                                                           # yes, I know this should be more readable!
                                                                           Raise TypeError('object x could not be converted to type y")



This allows for more customization on how a developer would want to return this object in various forms, and if, for example, the custom object was passed to something like json.dumps, it could try converting the object to something it recognizes first, or even try doing something like type(custom_object, json) and see what returned.

So, in implementation I might do something like:

def __conv__(self, to_class):
               if isinstance(to_class, (json, dict)):
                              return self._data_dict
               elif isinstance(to_class, ElementTree):
                              return self._get_xml_dict()
               else:
                                             raise TypeError('could not convert object to class')


This allows for developers of classes that operate on data passed to be able to define a process that they would use to accept unknown objects,  without having to worry about handling all of the different potential object types, and pass the responsibility for how to structure the information to the developer of the custom object.





From bc at freeuk.com  Fri Nov  6 14:30:54 2015
From: bc at freeuk.com (Bartc)
Date: Fri, 6 Nov 2015 19:30:54 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.90.1446826322.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
Message-ID: <n1iv1c$hst$1@dont-email.me>

On 06/11/2015 16:12, Lorenzo Sutton wrote:
>
>
> On 06/11/2015 13:30, Bartc wrote:
>> On 06/11/2015 02:33, wangq at travelsky.com wrote:
>>> Hello, python-list guys:
>>>
>>>      I am a newbie of python from Beijing. China.
>>>      I have a question about "math.pi".
>>>      As you can see in the attachment, why i can modify "math.pi"?
>>>      (in "mathmodule.c" "pi" is a "static const double")
>>
>> Python isn't C.
>>
>> Your attachment isn't visible, but it can be demonstrated easily:
>>
>> import math
>>
>> math.pi=0
>>
>> print (math.pi)
>>
>> In Python, presumably 'pi' is just another variable, and variables can
>> be written to.
>>
>> (Perhaps math.pi would be better off as a function.)
>
> Still nothing stops you from doing:
>
> math.sin = 0
>
> If you really want to?

Well, you might notice something is wrong when you try and do math.sin(x)!

But I see your point. Even a function can be set to another function, or 
to one that returns a nonsense value.

Is there no way then in Python to declare:

    pi = 3.141519     # etc

and make it impossible to override?

-- 
Bartc


From rosuav at gmail.com  Fri Nov  6 14:40:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 7 Nov 2015 06:40:38 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n1iv1c$hst$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
Message-ID: <CAPTjJmoXoyjwyH1Uza2H86RhTMkatHhM3QDPpiR_8hKkiB71rQ@mail.gmail.com>

On Sat, Nov 7, 2015 at 6:30 AM, Bartc <bc at freeuk.com> wrote:
> Is there no way then in Python to declare:
>
>    pi = 3.141519     # etc
>
> and make it impossible to override?

Nope. Even in C++, where classes can define certain things as const,
private, and other such restrictions, you can always get around them
by manipulating pointers appropriately. In Python, there's a
*convention* that a leading underscore means "private", but the
language doesn't enforce anything about it.

ChrisA


From rurpy at yahoo.com  Fri Nov  6 14:52:33 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Fri, 6 Nov 2015 11:52:33 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <n1f39d$o44$1@dont-email.me>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
 <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>
 <n1f39d$o44$1@dont-email.me>
Message-ID: <a379f9ca-dd27-412c-a005-bfef9b9e6abc@googlegroups.com>

On 11/05/2015 01:18 AM, Christian Gollwitzer wrote:
> Am 05.11.15 um 06:59 schrieb rurpy:
>>> Can you call yourself a well-rounded programmer without at least
>>> a basic understanding of some regex library? Well, probably not.
>>> But that's part of the problem with regexes. They have, to some
>>> degree, driven out potentially better -- or at least differently
>>> bad -- pattern matching solutions, such as (E)BNF grammars,
>>> SNOBOL pattern matching, or lowly globbing patterns. Or even
>>> alternative idioms, like Hypercard's "chunking" idioms.
>> 
>> Hmm, very good point.  I wonder why all those "potentially better" 
>> solutions have not been more widely adopted?  A conspiracy by a 
>> secret regex cabal?
> 
> I'm mostly on the pro-side of the regex discussion, but this IS a
> valid point. regexes are not always a good way to express a pattern,
> even if the pattern is regular. The point is, that you can't build
> them up easily piece-by-piece. Say, you want a regex like "first an
> international phone number, then a name, then a second phone number"
> - you will have to *repeat* the pattern for phone number twice. In
> more complex cases this can become a nightmare, like the monster that
> was mentioned before to validate an email.
> 
> A better alternative, then, is PEG for example. You can easily write
> [...]

That is the solution adopted by Perl 6. I have always thought lexing
and parsing solutions for Python were a weak spot in the Python eco-
system and I was about to write that I would love to see a PEG parser
for python when I saw this:

http://fdik.org/pyPEG/

Unfortunately it suffers from the same problem that Pyparsing, Ply
and the rest suffer from: they use Python syntax to express the
parsing rules rather than using a dedicated problem-specific syntax
such as you used to illustrate peg parsing:

> pattern <- phone_number name phone_number phone_number <- '+' [0-9]+
> ( '-' [0-9]+ )* name <-  [[:alpha:]]+

Some here have complained about excessive brevity of regexs but I
much prefer using problem-specific syntax like "(a*)" to having to
express a pattern using python with something like

star = RegexMatchAny()
a_group = RegexGroup('a' + star)
...

and I don't want to have to do something similar with PEG (or Ply
or Pyparsing) to formulate their rules.

>[...]
> As a 12 year old, not knowing anything about pattern recognition, but
> thinking I was the king, as is usual for boys in that age, I sat down
> and manually constructed a recursive descent parser in a BASIC like
> language. It had 1000 lines and took me a few weeks to get it
> correct. Finally the solution was accepted as working, but my
> participation was rejected because the solutions lacked
> documentation. 16 years later I used the problem for a course on
> string processing (that's what the PDF is for), and asked the
> students to solve it using regexes. My own solution consists of 67
> characters, and it took me5 minutes to write it down.
> 
> Admittedly, this problem is constructed, but solving similar tasks by
> regexes is still something that I need to do on a daily basis, when I
> get data from other scientists in odd formats and I need to
> preprocess them. I know people who use a spreadsheet and copy/paste
> millions of datapoints manually becasue they lack the knowledge of
> using such tools.

I think in many cases those most hostile to regexes are the also
those who use them (or need to use them) the least. While my use
of regexes are limited to fairly simple ones they are complicated
enough that I'm sure it would take orders of magnitude longer
to get the same effect in python.


From jana1972 at centrum.cz  Fri Nov  6 14:55:34 2015
From: jana1972 at centrum.cz (Jahn)
Date: Fri, 06 Nov 2015 20:55:34 +0100
Subject: PIL module for 64bit Python 2.7 
Message-ID: <563D05B6.18050.1A20E27@jana1972.centrum.cz>

Can anyone lat me know where I can download PIL module for 64bit Python 2.7 ?
 I found for 32 bit  Python 2.7 only  and the installation ended with an error that the 
Python 2.7 was not found in registers.
Thank you



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus



From auriocus at gmx.de  Fri Nov  6 14:59:57 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Fri, 6 Nov 2015 20:59:57 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.93.1446838846.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.93.1446838846.16136.python-list@python.org>
Message-ID: <n1j0nt$odf$1@dont-email.me>

Am 06.11.15 um 20:40 schrieb Chris Angelico:
> On Sat, Nov 7, 2015 at 6:30 AM, Bartc <bc at freeuk.com> wrote:
>> Is there no way then in Python to declare:
>>
>>     pi = 3.141519     # etc
>>
>> and make it impossible to override?
>
> Nope. Even in C++, where classes can define certain things as const,
> private, and other such restrictions, you can always get around them
> by manipulating pointers appropriately.

No, that is not right. If you cast away the constness from a pointer to 
a constant, you can technically write to that memory, but the behaviour 
is undefined - another way of saying that the program is illegal.

In many cases, the compiler will inline the constant - because you 
promised, that it can't change - and the update to the constant will not 
change in all parts of the program:


apfelkiste:Tests chris$ cat constub.cpp
#include <iostream>

void call_by_ref(const double &v) {
	std::cout<<"In function: v="<<v<<std::endl;
}

int main() {
	const double pi=3.14;
	double *errptr = const_cast<double*>(&pi);
	*errptr= 0.0;
	std::cout<<"Now pi is "<<pi<<std::endl;

	call_by_ref(pi);
	return 0;
}
apfelkiste:Tests chris$ g++ constub.cpp
apfelkiste:Tests chris$ ./a.out
Now pi is 3.14
In function: v=0


	Christian





From stephane at wirtel.be  Fri Nov  6 15:05:03 2015
From: stephane at wirtel.be (=?utf-8?q?St=C3=A9phane?= Wirtel)
Date: Fri, 06 Nov 2015 15:05:03 -0500
Subject: PIL module for 64bit Python 2.7
In-Reply-To: <563D05B6.18050.1A20E27@jana1972.centrum.cz>
References: <563D05B6.18050.1A20E27@jana1972.centrum.cz>
Message-ID: <78DD98F8-C454-48D1-8F6C-9F4BC48BB132@wirtel.be>

You can install Pillow, the API is the same.

and normally will compile for your architecture.
On 6 Nov 2015, at 14:55, Jahn wrote:

> Can anyone lat me know where I can download PIL module for 64bit Python 2.7 ?
> I found for 32 bit  Python 2.7 only  and the installation ended with an error that the
> Python 2.7 was not found in registers.
> Thank you
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
> -- 
> https://mail.python.org/mailman/listinfo/python-list


--
St?phane Wirtel - http://wirtel.be - @matrixise
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From kliateni at gmail.com  Fri Nov  6 15:34:42 2015
From: kliateni at gmail.com (Karim)
Date: Fri, 6 Nov 2015 21:34:42 +0100
Subject: Olivier Adret
In-Reply-To: <CAPTjJmriGNTidHNySNrjXCs8kdbhYWZb96DwmXwfs+s_p5_LsA@mail.gmail.com>
References: <563B74B6.80402@gmail.com>
 <CAPTjJmriGNTidHNySNrjXCs8kdbhYWZb96DwmXwfs+s_p5_LsA@mail.gmail.com>
Message-ID: <563D0EE2.4060207@gmail.com>



On 06/11/2015 11:34, Chris Angelico wrote:
> On Fri, Nov 6, 2015 at 2:24 AM, olivier <olivier.adret02 at gmail.com> wrote:
>>       Je vais essayer de programmer en python. On verra bien !
> Hello Olivier!
>
> This is a mostly English language mailing list/newsgroup, and there
> aren't many people who are fluent in French. There is, however, a
> corresponding French newsgroup, fr.comp.lang.python; you may find that
> you're more comfortable communicating there.
>
> My apologies for not responding in French, but I'm not very familiar
> with it, and all I would do is put my text through an online
> translation tool.
>
> Chris Angelico
Comme dit Chris, cette mailing liste est en anglais et tu peux aller sur 
le news group fr.comp.lang.python
pour du support en fran?ais. Mais je suppose que tu avais compris mais 
au cas o?.

Cordialement
Karim


From auriocus at gmx.de  Fri Nov  6 15:36:26 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Fri, 6 Nov 2015 21:36:26 +0100
Subject: Regular expressions
In-Reply-To: <a379f9ca-dd27-412c-a005-bfef9b9e6abc@googlegroups.com>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
 <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>
 <n1f39d$o44$1@dont-email.me>
 <a379f9ca-dd27-412c-a005-bfef9b9e6abc@googlegroups.com>
Message-ID: <n1j2s6$1qm$1@dont-email.me>

Am 06.11.15 um 20:52 schrieb rurpy at yahoo.com:
> I have always thought lexing
> and parsing solutions for Python were a weak spot in the Python eco-
> system and I was about to write that I would love to see a PEG parser
> for python when I saw this:
>
> http://fdik.org/pyPEG/
>
> Unfortunately it suffers from the same problem that Pyparsing, Ply
> and the rest suffer from: they use Python syntax to express the
> parsing rules rather than using a dedicated problem-specific syntax
> such as you used to illustrate peg parsing:
>
>> pattern <- phone_number name phone_number
 >> phone_number <- '+' [0-9]+ ( '-' [0-9]+ )*
 >> name <-  [[:alpha:]]+

That is actually real syntax of a parser generator used by me for 
another language (Tcl). A calculator example using this package can be 
found here: http://wiki.tcl.tk/39011
(actually it is a retargetable compiler in a few lines - very impressive)

And exactly as you say, it is working well exactly because it doesn't 
try to abuse function composition in the frontend to construct the parser.

Looking through the parser generators listed at 
http://bford.info/packrat/ it seems that waxeye could be interesting 
http://waxeye.org/manual.html#_using_waxeye - however I'm not sure the 
Python backend works with Python 3, maybe there will be unicode issues. 
Another bonus would be a compilable backend, like Cython or similar. The 
pt package mentioned above allows to generate a C module with an 
interface for Tcl. Compiled parsers are approximately 100x faster. I 
would expect a similar speedup for Python parsers.

> Some here have complained about excessive brevity of regexs but I
> much prefer using problem-specific syntax like "(a*)" to having to
> express a pattern using python with something like
>
> star = RegexMatchAny()
> a_group = RegexGroup('a' + star)
> ...

Yeah that is nonsense. Mechanical verbosity never leads to clarity (XML 
anyone?)

> I think in many cases those most hostile to regexes are the also
> those who use them (or need to use them) the least. While my use
> of regexes are limited to fairly simple ones they are complicated
> enough that I'm sure it would take orders of magnitude longer
> to get the same effect in python.

That's also my impression. The "two problems quote" was lame already for 
the first time. If you are satisfied with simple string functions, then 
either you do not have problems where you need regexps/other formal 
parsing tools, or you are very masochistic.

	Christian


From larry.martell at gmail.com  Fri Nov  6 15:42:47 2015
From: larry.martell at gmail.com (Larry Martell)
Date: Fri, 6 Nov 2015 15:42:47 -0500
Subject: Regular expressions
In-Reply-To: <n1j2s6$1qm$1@dont-email.me>
References: <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <56397FC6.9040700@gmail.com> <n1ch8v$irh$1@ger.gmane.org>
 <mailman.19.1446650043.16136.python-list@python.org>
 <3f3l3bpm478nbnsec6c9tr6rre0aontkq1@4ax.com>
 <5e15df62-00b1-4746-83f8-c0821514d20b@googlegroups.com>
 <563abdda$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <2fd7d161-b1cb-4274-b8dc-0157916413f1@googlegroups.com>
 <n1f39d$o44$1@dont-email.me>
 <a379f9ca-dd27-412c-a005-bfef9b9e6abc@googlegroups.com>
 <n1j2s6$1qm$1@dont-email.me>
Message-ID: <CACwCsY41Xgxya2+1Xu9C=5t4ZkFgE4JpykpFzRx2cNYyfp65EQ@mail.gmail.com>

On Fri, Nov 6, 2015 at 3:36 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> Am 06.11.15 um 20:52 schrieb rurpy at yahoo.com:
>>
>> I have always thought lexing
>> and parsing solutions for Python were a weak spot in the Python eco-
>> system and I was about to write that I would love to see a PEG parser
>> for python when I saw this:
>>
>> http://fdik.org/pyPEG/
>>
>> Unfortunately it suffers from the same problem that Pyparsing, Ply
>> and the rest suffer from: they use Python syntax to express the
>> parsing rules rather than using a dedicated problem-specific syntax
>> such as you used to illustrate peg parsing:
>>
>>> pattern <- phone_number name phone_number
>
>>> phone_number <- '+' [0-9]+ ( '-' [0-9]+ )*
>>> name <-  [[:alpha:]]+
>
> That is actually real syntax of a parser generator used by me for another
> language (Tcl). A calculator example using this package can be found here:
> http://wiki.tcl.tk/39011
> (actually it is a retargetable compiler in a few lines - very impressive)

Ah, Tcl - I wrote many a Tcl script back in the 80s to login to BBSs.


From rurpy at yahoo.com  Fri Nov  6 15:46:25 2015
From: rurpy at yahoo.com (rurpy at yahoo.com)
Date: Fri, 6 Nov 2015 12:46:25 -0800 (PST)
Subject: Regular expressions
In-Reply-To: <ftrm3btf2a8ik9h1uora8p1ptq4sqand60@4ax.com>
References: <mailman.0.1446519578.8789.python-list@python.org>
 <hp9g3b9hsn06edb0po8bduegjqkmpo4p8n@4ax.com>
 <mailman.3.1446523111.8789.python-list@python.org>
 <d39290cf-cb26-470f-a987-2f71e3860f97@googlegroups.com>
 <mailman.5.1446525488.8789.python-list@python.org>
 <bb15756d-7181-421d-835e-b2fbfc1c1774@googlegroups.com>
 <56398006$0$11100$c3e8da3@news.astraweb.com>
 <1i3l3b9836hatsuoopak5gtg2c38g49kb1@4ax.com>
 <563aa8be$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <ftrm3btf2a8ik9h1uora8p1ptq4sqand60@4ax.com>
Message-ID: <e17a32f3-3332-4452-bc26-c4097c137b78@googlegroups.com>

On Thursday, November 5, 2015 at 8:12:22 AM UTC-7, Seymore4Head wrote:
> On Thu, 05 Nov 2015 11:54:20 +1100, Steven D'Aprano <steve at pearwood.info> wrote:
> >On Thu, 5 Nov 2015 10:02 am, Seymore4Head wrote:
> >> So far the only use I have for regex is to replace slicing, but I
> >> think it is an improvement.
> >
> >I don't understand this. This is like saying "so far the only use I have for
> >a sandwich press is to replace my coffee pot". Regular expressions and
> >slicing do very different things.
> >[...]
> 
> Here is an example of the text we are slicing apart.
> 
>[...email headers...]
>
> The practice problems are something like pull out all the email
> addresses or pull out the days of the week and give the most common.

Yes, that is a perfectly appropriate use of regexes.

As Steven mentioned though, the term "slicing" is also used with a 
very specific and different meaning in Python, specifically referring
to a part of a list using a syntax like "alist[a:b]".  I can't seem
to get to python.org at the moment but if you look in the Python
docs index under "slicing" you'll find more info.
 


From RobinsW1 at sutterhealth.org  Fri Nov  6 16:36:00 2015
From: RobinsW1 at sutterhealth.org (Robinson, Wendy)
Date: Fri, 6 Nov 2015 13:36:00 -0800
Subject: Puzzled
In-Reply-To: <563CADCD.8070307@gonnerman.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
 <563CADCD.8070307@gonnerman.org>
Message-ID: <4CFEDC132D44AC49BA0E91FBEB947119084AAD2A1E@DCBL123VX.root.sutterhealth.org>

Ah, ok.... I get it now.
Thanks both!

Wendy Robinson
Audit Analyst


-----Original Message-----
From: Chris Gonnerman [mailto:chris at gonnerman.org] 
Sent: Friday, November 06, 2015 5:40 AM
To: python-list at python.org
Cc: Robinson, Wendy
Subject: Re: Puzzled

Wendy said:
> I installed Python 3.5.0 64-bit for Windows yesterday and tried some basic programs successfully.
> This morning I rebooted my computer and can't get a single one to work.  The interpreter seems to be fine and the environment variables look correct.  But every py file I try to run at the >>> prompt gives me a NameError.
But that's not how the Python interpreter works.  You say you are trying to run "py files" at the >>> prompt.  If what you are doing is this:

     >>> test.py

Well, no, that's not going to work.  If you want to run "test.py" as a script, from the CMD prompt you type:

     python test.py

If test.py is a module meant to be imported, then from the Python prompt you do this:

     import test

Hope this helps.

-- Chris.



From lac at openend.se  Fri Nov  6 16:37:58 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 06 Nov 2015 22:37:58 +0100
Subject: PIL module for 64bit Python 2.7 
In-Reply-To: <563D05B6.18050.1A20E27@jana1972.centrum.cz>
References: <563D05B6.18050.1A20E27@jana1972.centrum.cz>
Message-ID: <201511062137.tA6LbwcY027485@fido.openend.se>

In a message of Fri, 06 Nov 2015 20:55:34 +0100, "Jahn" writes:
>Can anyone lat me know where I can download PIL module for 64bit Python 2.7 ?
> I found for 32 bit  Python 2.7 only  and the installation ended with an error that the 
>Python 2.7 was not found in registers.
>Thank you

The Modern Fork of PIL is Pillow.
hhttps://pypi.python.org/pypi/Pillow/3.0.0

Laura 



From stephane at wirtel.be  Fri Nov  6 16:40:49 2015
From: stephane at wirtel.be (=?utf-8?q?St=C3=A9phane?= Wirtel)
Date: Fri, 06 Nov 2015 16:40:49 -0500
Subject: PIL module for 64bit Python 2.7
In-Reply-To: <201511062137.tA6LbwcY027485@fido.openend.se>
References: <563D05B6.18050.1A20E27@jana1972.centrum.cz>
 <201511062137.tA6LbwcY027485@fido.openend.se>
Message-ID: <4D43805F-873A-4D8C-9507-3B63B5CD3FF3@wirtel.be>

Really strange, I have sent the same answer, there is one hour. Did you receive it ?

I am not but maybe I have a problem with my email.
On 6 Nov 2015, at 16:37, Laura Creighton wrote:

> In a message of Fri, 06 Nov 2015 20:55:34 +0100, "Jahn" writes:
>> Can anyone lat me know where I can download PIL module for 64bit Python 2.7 ?
>> I found for 32 bit  Python 2.7 only  and the installation ended with an error that the
>> Python 2.7 was not found in registers.
>> Thank you
>
> The Modern Fork of PIL is Pillow.
> hhttps://pypi.python.org/pypi/Pillow/3.0.0
>
> Laura
>
> -- 
> https://mail.python.org/mailman/listinfo/python-list


--
St?phane Wirtel - http://wirtel.be - @matrixise
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From random832 at fastmail.com  Fri Nov  6 16:56:50 2015
From: random832 at fastmail.com (Random832)
Date: Fri, 06 Nov 2015 16:56:50 -0500
Subject: argparse: use of double dash to separate options and positional
 arguments
References: <20151106100743.GN3685@isis.luna> <n1i126$o2f$1@ger.gmane.org>
Message-ID: <87vb9eeqql.fsf@fastmail.com>

Peter Otten <__peter__ at web.de> writes:

> I'm not sure about this one; one purpose of REMAINDER is to pass on the 
> unprocessed arguments to another program/script, and this might follow the 
> same convention. Should
>
> parser.add_argument('-v', '--verbose', action='store_true')
> parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
> args = parser.parse_args()
> subprocess.call(["rm"] + args.cmd_args)
>
> $ my_prog -v -- -r foo
>
> attempt to delete two files "-r" and "foo" or remove the "foo" directory? 
> The first is the safer alternative, and as you say stripping the "--" is 
> easy.

I think it should be the second. If the caller wants it to be treated as
a list of files rather than a list of arguments, it should be using
subprocess.call(["rm", "--"] + args.cmd_args).

The purpose is, as you said, to pass the *unprocessed* argument. -- has
been processed by being interpreted as a terminator for the argument
list.

I have a script (it's a shell script, not a python script) where I
actually do something similar... it does some setup, then calls ssh. If
I want to pass some options directly to ssh, I call it as:
"scriptname -script-option -- -ssh-option remote-command"




From abhishek.mallela at gmail.com  Fri Nov  6 17:01:08 2015
From: abhishek.mallela at gmail.com (Abhishek)
Date: Fri, 6 Nov 2015 14:01:08 -0800 (PST)
Subject: Scipy odeint (LSODA) gives inaccurate results; same code fine in
 MATLAB ode15s/ode23s
Message-ID: <942d2bd0-6322-4733-a6dd-ceeed40368cb@googlegroups.com>

I have code that runs perfectly well in MATLAB (using ode15s or ode23s) but falters with Scipy odeint. The MATLAB code is for a specific case of the generalized Python code. Here I have tried to reproduce the specific case in Python. The logic in the code is airtight and the algorithm is sound. I have also specified small rtol and atol values, as well as a large mxstep. 

My code is below:

    import numpy as np
    import matplotlib.pyplot as plt
    from scipy.integrate import odeint
    
    #Constants and parameters
    N = 2
    K00 = np.logspace(0,3,101,10)
    len1 = len(K00)
    epsilon = 0.01
    y0 = [0]*(3*N/2+3)
    u1 = 0
    u2 = 0
    u3 = 0
    Kplot = np.zeros((len1,1))
    Pplot = np.zeros((len1,1))
    S = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    KS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    PS = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    Splot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    KSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    PSplot = [np.zeros((len1,1)) for kkkk in range(N/2+1)]
    
    for series in range(0,len1):
        K0 = K00[series]
        Q = 10
        r1 = 0.0001
        r2 = 0.001
        a = 0.001
        d = 0.001
        k = 0.999
        S10 = 1e5
        P0 = 1
        tfvec = np.tile(1e10,(1,5))
        tf = tfvec[0,0]
        time = np.linspace(0,tf,len1)
    
        #Defining dy/dt's
        def f(y,t):
            for alpha in range(0,(N/2+1)):
                S[alpha] = y[alpha]
            for beta in range((N/2)+1,N+1):
                KS[beta-N/2-1] = y[beta]
            for gamma in range(N+1,3*N/2+1):
                PS[gamma-N] = y[gamma]
            K = y[3*N/2+1]
            P = y[3*N/2+2]
    
            # The model equations
            ydot = np.zeros((3*N/2+3,1))
            B = range((N/2)+1,N+1)
            G = range(N+1,3*N/2+1)
            runsumPS = 0
            runsum1 = 0
            runsumKS = 0
            runsum2 = 0
    
            for m in range(0,N/2):
                runsumPS = runsumPS + PS[m+1]
                runsum1 = runsum1 + S[m+1]
                runsumKS = runsumKS + KS[m]
                runsum2 = runsum2 + S[m]
                ydot[B[m]] = a*K*S[m]-(d+k+r1)*KS[m]
    
            for i in range(0,N/2-1):
                ydot[G[i]] = a*P*S[i+1]-(d+k+r1)*PS[i+1]
    
            for p in range(1,N/2):
                ydot[p] = -S[p]*(r1+a*K+a*P)+k*KS[p-1]+ \
                          d*(PS[p]+KS[p])
    
            ydot[0] = Q-(r1+a*K)*S[0]+d*KS[0]+k*runsumPS
            ydot[N/2] = k*KS[N/2-1]-(r2+a*P)*S[N/2]+ \
                        d*PS[N/2]
            ydot[G[N/2-1]] = a*P*S[N/2]-(d+k+r2)*PS[N/2]
            ydot[3*N/2+1] = (d+k+r1)*runsumKS-a*K*runsum2
            ydot[3*N/2+2] = (d+k+r1)*(runsumPS-PS[N/2])- \
                            a*P*runsum1+(d+k+r2)*PS[N/2]
    
            ydot_new = []
            for j in range(0,3*N/2+3):
                ydot_new.extend(ydot[j])
            return ydot_new
            
        # Initial conditions
        y0[0] = S10
        for i in range(1,3*N/2+1):
            y0[i] = 0
        y0[3*N/2+1] = K0
        y0[3*N/2+2] = P0
    
        # Solve the DEs
        soln = odeint(f,y0,time,rtol = 1e-12, atol = 1e-14, mxstep = 50000000)
        for alpha in range(0,(N/2+1)):
            S[alpha] = soln[:,alpha]
        for beta in range((N/2)+1,N+1):
            KS[beta-N/2-1] = soln[:,beta]
        for gamma in range(N+1,3*N/2+1):
            PS[gamma-N] = soln[:,gamma]
    
        for alpha in range(0,(N/2+1)):
            Splot[alpha][series] = soln[len1-1,alpha]
        for beta in range((N/2)+1,N+1):
            KSplot[beta-N/2-1][series] = soln[len1-1,beta]
        for gamma in range(N+1,3*N/2+1):
            PSplot[gamma-N][series] = soln[len1-1,gamma]
    
        for alpha in range(0,(N/2+1)):
            u1 = u1 + Splot[alpha]
        for beta in range((N/2)+1,N+1):
            u2 = u2 + KSplot[beta-N/2-1]
        for gamma in range(N+1,3*N/2+1):
            u3 = u3 + PSplot[gamma-N]
    
        K = soln[:,3*N/2+1]
        P = soln[:,3*N/2+2]
        Kplot[series] = soln[len1-1,3*N/2+1]
        Pplot[series] = soln[len1-1,3*N/2+2]
        utot = u1+u2+u3
    
    #Plot
    plt.plot(np.log10(K00),utot[:,0])
    plt.show()

Why am I getting a "stiff-looking" graph in Python (http://i.stack.imgur.com/UGWSH.png), when MATLAB gives me a proper one (http://i.stack.imgur.com/F2jzd.jpg)? I would like to understand where the problem lies and how to solve it.

Thanks in advance for any help.


From PointedEars at web.de  Fri Nov  6 17:19:42 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Fri, 06 Nov 2015 23:19:42 +0100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.93.1446838846.16136.python-list@python.org>
Message-ID: <1521937.lCYGF7V2BE@PointedEars.de>

Chris Angelico wrote:

> On Sat, Nov 7, 2015 at 6:30 AM, Bartc <bc at freeuk.com> wrote:
>> Is there no way then in Python to declare:
>>
>>    pi = 3.141519     # etc
>>
>> and make it impossible to override?
> 
> Nope. Even in C++, where classes can define certain things as const,
> private, and other such restrictions, you can always get around them
> by manipulating pointers appropriately. In Python, there's a
> *convention* that a leading underscore means "private", but the
> language doesn't enforce anything about it.

It is certainly possible for attributes of (instances of) new-style classes 
(starting with Python 3.2 at the latest) to be read-only by declaring them a 
property that does not have a setter, or one that has a setter that throws a 
specific exception (here: the former):

#--------------------------
class SafeMath(object):
    def __init__ (self):
        from math import pi
        self._pi = pi
    
    @property
    def pi (self):
        return self._pi

#--------------------------

| >>> math = SafeMath()
| >>> math.pi
| 3.141592653589793
| >>> math.pi = 42
| Traceback (most recent call last):
|   File "<stdin>", line 1, in <module>
| AttributeError: can't set attribute

(Or you can use ?pi = property(?)? within the class declaration.)

In theory, it should be possible to substitute ?math? with a reference to an 
object that acts as a proxy for the original ?math? module object but whose 
base class declares the attributes for all the constants read-only.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From PointedEars at web.de  Fri Nov  6 17:26:49 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Fri, 06 Nov 2015 23:26:49 +0100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
Message-ID: <1590467.kktH0DaBsW@PointedEars.de>

Bartc wrote:
^^^^^
Please fix.

> On 06/11/2015 02:33, wangq at travelsky.com wrote:
>>      As you can see in the attachment, why i can modify "math.pi"?
>>      (in "mathmodule.c" "pi" is a "static const double")
> 
> Python isn't C.
> 
> Your attachment isn't visible, but it can be demonstrated easily:
> 
> import math
> 
> math.pi=0
> 
> print (math.pi)
> 
> In Python, presumably 'pi' is just another variable, and variables can
> be written to.

?pi? is the name of an attribute of the module object referred to by ?math?.
 
> (Perhaps math.pi would be better off as a function.)

Perhaps not.  Calling a function includes an overhead that one does not want 
in already costly floating-point calculations.

In my opinion, mathematical constants should be implemented as constants 
(non-overwritable, non-deletable, throwing exceptions when attempting to do 
either) but apparently the authors of math.py disagree.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From scott.werner.vt at gmail.com  Fri Nov  6 17:29:57 2015
From: scott.werner.vt at gmail.com (Scott Werner)
Date: Fri, 6 Nov 2015 14:29:57 -0800 (PST)
Subject: Script to extract text from PDF files
In-Reply-To: <fdbh95$smc$1@solaris.cc.vt.edu>
References: <fdbh95$smc$1@solaris.cc.vt.edu>
Message-ID: <ebeea6ba-f26b-452d-8a75-1338f3a4a9f6@googlegroups.com>

On Tuesday, September 25, 2007 at 1:41:56 PM UTC-4, brad wrote:
> I have a very crude Python script that extracts text from some (and I 
> emphasize some) PDF documents. On many PDF docs, I cannot extract text, 
> but this is because I'm doing something wrong. The PDF spec is large and 
> complex and there are various ways in which to store and encode text. I 
> wanted to post here and ask if anyone is interested in helping make the 
> script better which means it should accurately extract text from most 
> any pdf file... not just some.
> 
> I know the topic of reading/extracting the text from a PDF document 
> natively in Python comes up every now and then on comp.lang.python... 
> I've posted about it in the past myself. After searching for other 
> solutions, I've resorted to attempting this on my own in my spare time. 
> Using apps external to Python (pdftotext, etc.) is not really an option 
> for me. If someone knows of a free native Python app that does this now, 
> let me know and I'll use that instead!
> 
> So, if other more experienced programmer are interested in helping make 
> the script better, please let me know. I can host a website and the 
> latest revision and do all of the grunt work.
> 
> Thanks,
> 
> Brad

As mentioned before, extracting plain text from a PDF document can be hit or miss. I have tried all the following applications (free/open source) on Arch Linux. Note, I would execute the commands with subprocess and capture stdout or read plain text file created by the application.

* textract (uses pdftotext)
- https://github.com/deanmalmgren/textract

* pdftotext 
- http://poppler.freedesktop.org/
- cmd: pdftotext -layout "/path/to/document.pdf" -
- cmd: pdftotext "/path/to/document.pdf" -

* Calibre
- http://calibre-ebook.com/
- cmd: ebook-convert "/path/to/document.pdf" "/path/to/plain.txt" --no-chapters-in-toc

* AbiWord
- http://www.abiword.org/
- cmd: abiword --to-name=fd://1 --to-TXT "/path/to/document.pdf"

* Apache Tika
- https://tika.apache.org/
- cmd: "/usr/bin/java" -jar "/path/to/standalone/tika-app-1.10.jar" --text-main "/path/to/document.pdf"

For my application, I saw the best results using Apache Tika. However, I do still encounter strange encoding or extraction issues, e.g. S P A C E D  O U T  H E A D E R S" and "\nBroken \nHeader\n". I ended up writing a lot of repairing/cleaning methods.

I welcome an improved solution that has some intelligence like comparing the extract plain text order to a snapshot of the pdf page using OCR.


From D.Strohl at F5.com  Fri Nov  6 17:46:01 2015
From: D.Strohl at F5.com (Dan Strohl)
Date: Fri, 6 Nov 2015 22:46:01 +0000
Subject: Script to extract text from PDF files
In-Reply-To: <ebeea6ba-f26b-452d-8a75-1338f3a4a9f6@googlegroups.com>
References: <fdbh95$smc$1@solaris.cc.vt.edu>
 <ebeea6ba-f26b-452d-8a75-1338f3a4a9f6@googlegroups.com>
Message-ID: <40c22d28dbb546a6959fae9129493bfa@seaexchmbx03.olympus.F5Net.com>

Its possible (likely) that I came into this in the middle, so sorry if this was already thrown out... but have you looked at any of the following suggestions?

https://pypi.python.org/pypi?%3Aaction=search&term=pdf+convert&submit=search
http://stackoverflow.com/questions/6413441/python-pdf-library
https://www.binpress.com/tutorial/manipulating-pdfs-with-python/167



-----Original Message-----
From: Python-list [mailto:python-list-bounces+d.strohl=f5.com at python.org] On Behalf Of Scott Werner
Sent: Friday, November 06, 2015 2:30 PM
To: python-list at python.org
Subject: Re: Script to extract text from PDF files

On Tuesday, September 25, 2007 at 1:41:56 PM UTC-4, brad wrote:
> I have a very crude Python script that extracts text from some (and I 
> emphasize some) PDF documents. On many PDF docs, I cannot extract 
> text, but this is because I'm doing something wrong. The PDF spec is 
> large and complex and there are various ways in which to store and 
> encode text. I wanted to post here and ask if anyone is interested in 
> helping make the script better which means it should accurately 
> extract text from most any pdf file... not just some.
> 
> I know the topic of reading/extracting the text from a PDF document 
> natively in Python comes up every now and then on comp.lang.python...
> I've posted about it in the past myself. After searching for other 
> solutions, I've resorted to attempting this on my own in my spare time.
> Using apps external to Python (pdftotext, etc.) is not really an 
> option for me. If someone knows of a free native Python app that does 
> this now, let me know and I'll use that instead!
> 
> So, if other more experienced programmer are interested in helping 
> make the script better, please let me know. I can host a website and 
> the latest revision and do all of the grunt work.
> 
> Thanks,
> 
> Brad

As mentioned before, extracting plain text from a PDF document can be hit or miss. I have tried all the following applications (free/open source) on Arch Linux. Note, I would execute the commands with subprocess and capture stdout or read plain text file created by the application.

* textract (uses pdftotext)
- https://github.com/deanmalmgren/textract

* pdftotext
- http://poppler.freedesktop.org/
- cmd: pdftotext -layout "/path/to/document.pdf" -
- cmd: pdftotext "/path/to/document.pdf" -

* Calibre
- http://calibre-ebook.com/
- cmd: ebook-convert "/path/to/document.pdf" "/path/to/plain.txt" --no-chapters-in-toc

* AbiWord
- http://www.abiword.org/
- cmd: abiword --to-name=fd://1 --to-TXT "/path/to/document.pdf"

* Apache Tika
- https://tika.apache.org/
- cmd: "/usr/bin/java" -jar "/path/to/standalone/tika-app-1.10.jar" --text-main "/path/to/document.pdf"

For my application, I saw the best results using Apache Tika. However, I do still encounter strange encoding or extraction issues, e.g. S P A C E D  O U T  H E A D E R S" and "\nBroken \nHeader\n". I ended up writing a lot of repairing/cleaning methods.

I welcome an improved solution that has some intelligence like comparing the extract plain text order to a snapshot of the pdf page using OCR.
--
https://mail.python.org/mailman/listinfo/python-list


From PointedEars at web.de  Fri Nov  6 18:48:40 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Sat, 07 Nov 2015 00:48:40 +0100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.93.1446838846.16136.python-list@python.org>
 <1521937.lCYGF7V2BE@PointedEars.de>
Message-ID: <11393078.50naPz65Nn@PointedEars.de>

Thomas 'PointedEars' Lahn wrote:

> In theory, it should be possible to substitute ?math? with a reference to
> an object that acts as a proxy for the original ?math? module object but
> whose base class declares the attributes for all the constants read-only.

#!/usr/bin/env python3
#---------------------------------------------------------------------------

import importlib

class MyMath(object):
    def getter_factory (prop):
        def getter (self):
            return getattr(importlib.__import__("math", globals(), locals(),
                        [prop], 0), prop)
        return getter

    pi = property(getter_factory("pi"), lambda self, val: None,
            lambda self: None)
    e = property(getter_factory("e"), lambda self, val: None,
            lambda self: None)
    inf = property(getter_factory("inf"), lambda self, val: None,
            lambda self: None)
    nan = property(getter_factory("nan"), lambda self, val: None,
            lambda self: None)

    def __getattr__ (self, name):
        return getattr(importlib.__import__("math", globals(), locals(),
                    [name], 0), name, None)

math = MyMath()

print(math.pi, math.e, math.inf, math.nan)

math.pi = 42
math.e = 42
math.inf = 42
math.nan = 42

print(math.pi, math.e, math.inf, math.nan)
print(math.ceil(2.41))
#---------------------------------------------------------------------------

Using property() instead of decorators here was intended to achieve DRY by 
using a loop, but I could not find a way to define class attributes 
dynamically.  Suggestions?

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From tjreedy at udel.edu  Fri Nov  6 20:49:17 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 6 Nov 2015 20:49:17 -0500
Subject: Question about math.pi is mutable
In-Reply-To: <1590467.kktH0DaBsW@PointedEars.de>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
Message-ID: <n1jlav$8ap$1@ger.gmane.org>

On 11/6/2015 5:26 PM, Thomas 'PointedEars' Lahn wrote:
> Bartc wrote:

>> import math
>>
>> math.pi=0
>>
>> print (math.pi)
>>
>> In Python, presumably 'pi' is just another variable, and variables can
>> be written to.
>
> ?pi? is the name of an attribute of the module object referred to by ?math?.
>
>> (Perhaps math.pi would be better off as a function.)
>
> Perhaps not.  Calling a function includes an overhead that one does not want
> in already costly floating-point calculations.
>
> In my opinion, mathematical constants should be implemented as constants
> (non-overwritable, non-deletable, throwing exceptions when attempting to do
> either) but apparently the authors of math.py disagree.

One of multiple discussions of the 'constants' idea.
bugs.python.org/issue1465406
It is mostly about speed.

-- 
Terry Jan Reedy




From steve at pearwood.info  Fri Nov  6 21:00:31 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 07 Nov 2015 13:00:31 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.93.1446838846.16136.python-list@python.org>
 <1521937.lCYGF7V2BE@PointedEars.de>
Message-ID: <563d5b41$0$1585$c3e8da3$5496439d@news.astraweb.com>

On Sat, 7 Nov 2015 09:19 am, Thomas 'PointedEars' Lahn wrote:

> It is certainly possible for attributes of (instances of) new-style
> classes (starting with Python 3.2 at the latest) to be read-only by
> declaring them a property that does not have a setter, or one that has a
> setter that throws a specific exception (here: the former):
> 
> #--------------------------
> class SafeMath(object):
>     def __init__ (self):
>         from math import pi
>         self._pi = pi
>     
>     @property
>     def pi (self):
>         return self._pi

The obvious problem with that is that it is trivially easy for the coder to
set self._pi to change the value of self.pi.

Here's a version that at first seems promising:

py> def builder():
...     from math import pi as PI
...     def pi(self):
...             return PI
...     return pi
...
py> class MathLib(object):
...     pi = property(builder())
...
py> mathlib = MathLib()
py> mathlib.pi
3.141592653589793
py> mathlib.pi = 3.12
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: can't set attribute

There's no _pi accessible that somebody might change. If you dig into the
property object itself, you eventually get to the cell object containing
the value for pi:

py> MathLib.pi.fget.__closure__[0]
<cell at 0xb7bd5134: float object at 0xb7be5c30>

but there doesn't appear to be any way to manipulate the cell internals to
change the value. But you don't need to:

py> MathLib.pi = property(lambda self: 4.2)
py> mathlib.pi
4.2


A determined coder can change nearly anything done in pure Python code.

*Personally*, I too would like Python to have some equivalent of (say)
Pascal `const`, names which cannot be rebound once assigned to the first
time. Not to prevent determined coders from changing things, but to avoid
*accidental* changes done in error.



-- 
Steven



From steve at pearwood.info  Fri Nov  6 21:06:07 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 07 Nov 2015 13:06:07 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
Message-ID: <563d5c90$0$1599$c3e8da3$5496439d@news.astraweb.com>

On Sat, 7 Nov 2015 09:26 am, Thomas 'PointedEars' Lahn wrote:
....................................^^^^^^^^^^^^^

> Bartc wrote:
> ^^^^^
> Please fix.

Why? There's nothing wrong with somebody signing their posts "Bartc". It is
no more silly than somebody calling themselves "PointedEars". Please stop
trying to enforce non-existent rules about internet identities on others.



-- 
Steven



From orgnut at yahoo.com  Fri Nov  6 22:21:32 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Fri, 6 Nov 2015 19:21:32 -0800
Subject: =?UTF-8?B?UmU6IFdoYXQgZG9lcyDigJxncmVw4oCdIHN0YW5kIGZvcj8=?=
In-Reply-To: <mailman.88.1446819949.16136.python-list@python.org>
References: <mailman.0.1446602668.16136.python-list@python.org>
 <n1bs2g$376$1@dont-email.me> <56397a18$0$11094$c3e8da3@news.astraweb.com>
 <mailman.23.1446661467.16136.python-list@python.org>
 <n1dmn7$fnq$1@dont-email.me>
 <CAPTjJmrSwiU657oasBQh6GuZnxB0SyX2wG+WcMwZ7bTy6NxygQ@mail.gmail.com>
 <mailman.56.1446736776.16136.python-list@python.org>
 <n1g76u$85u$1@reader1.panix.com>
 <mailman.63.1446753408.16136.python-list@python.org>
 <n1gdkr$mce$1@reader1.panix.com>
 <mailman.67.1446772690.16136.python-list@python.org>
 <NtKdnfI0w7uxvaHLnZ2dnUU7-cednZ2d@giganews.com>
 <mailman.88.1446819949.16136.python-list@python.org>
Message-ID: <ZbudnT1XFfKg86DLnZ2dnUU7-T2dnZ2d@giganews.com>

On 11/06/2015 05:25 AM, William Ray Wing wrote:
>
>> On Nov 5, 2015, at 10:36 PM, Larry Hudson via Python-list <python-list at python.org> wrote:
>>
[snip]
> You?re not REALLY an old timer unless you?ve used TECO.
>
> -Bill
>
Agreed.  I'm not really and old-timer, just old (I'm 78).

My first exposure to computers was the MITS Altair, (around late '75) and my computer use has 
always been hobby-oriented, never professional.  I only know of TECO by reputation, not 
experience.   :-)

      -=- Larry -=-



From ben+python at benfinney.id.au  Fri Nov  6 22:43:44 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 07 Nov 2015 14:43:44 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
Message-ID: <857flujwy7.fsf@benfinney.id.au>

Bartc <bc at freeuk.com> writes:

> Is there no way then in Python to declare:
>
>    pi = 3.141519     # etc
>
> and make it impossible to override?

No, and it would be a bad thing if that were something a library author
could forbid.

Python assumes the programmers using it are consenting adults. Doing
harmful things is difficult but not forbidden.

Notably, the author of a library should not be forbidding the Pythonic
ability to change name bindings as needed.

If you want to have a different value bound to the name ?math.pi?, and
you go ahead and explicitly ask to change that binding, the library
author has no business forbidding that.

-- 
 \      ?Software patents provide one more means of controlling access |
  `\      to information. They are the tool of choice for the internet |
_o__)                                     highwayman.? ?Anthony Taylor |
Ben Finney



From baruchel at no.spam.gmx.dot.com  Sat Nov  7 01:53:27 2015
From: baruchel at no.spam.gmx.dot.com (Th. Baruchel)
Date: 07 Nov 2015 06:53:27 GMT
Subject: Version 1.1 of the tco module (tail-calls, recursion, call/cc)
Message-ID: <563d9fe7$0$3054$426a74cc@news.free.fr>

The version 1.1 of the tco module is released. It is much more owerful since
it now allows nested systems of continuations. The most important is probably
rather that I took the time to write a very detailed presentation of the
module on my blog: http://baruchel.github.io/

Regards, tb.


From auriocus at gmx.de  Sat Nov  7 01:54:48 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 7 Nov 2015 07:54:48 +0100
Subject: Scipy odeint (LSODA) gives inaccurate results; same code fine in
 MATLAB ode15s/ode23s
In-Reply-To: <942d2bd0-6322-4733-a6dd-ceeed40368cb@googlegroups.com>
References: <942d2bd0-6322-4733-a6dd-ceeed40368cb@googlegroups.com>
Message-ID: <n1k73h$agh$1@dont-email.me>

Am 06.11.15 um 23:01 schrieb Abhishek:
> I have code that runs perfectly well in MATLAB (using ode15s or
> ode23s) but falters with Scipy odeint. The MATLAB code is for a
> specific case of the generalized Python code. Here I have tried to
> reproduce the specific case in Python. The logic in the code is
> airtight and the algorithm is sound. I have also specified small rtol
> and atol values, as well as a large mxstep.
>
> My code is below:
>
> [...Python code...]

>
> Why am I getting a "stiff-looking" graph in Python

What does "stiff-looking" mean? I only know stiff differential 
equations, but this leads to noisy results. Your plots are smooth.

> (http://i.stack.imgur.com/UGWSH.png), when MATLAB gives me a proper
> one (http://i.stack.imgur.com/F2jzd.jpg)? I would like to understand
> where the problem lies and how to solve it.

It is very hard to analyze such a problem, unless you also post the 
Matlab code and plot both solutions into a single graph.

What I can see at first is that the initial conditions can't be the 
same. Your Python graph starts around 10^7, while the Matlab graph 
starts at 10^5. WHat happens if you integrate a simpler system - say 
does it make sense to set some of the coefficients to zero and if you 
still get the same difference, can you simplify the program to expose 
the problem? How do you know that the Matlab code produces the correct 
answer?

	Christian


From bc at freeuk.com  Sat Nov  7 06:23:59 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 11:23:59 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.103.1446867842.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
Message-ID: <n1kmse$p0o$1@dont-email.me>

On 07/11/2015 03:43, Ben Finney wrote:
> Bartc <bc at freeuk.com> writes:
>
>> Is there no way then in Python to declare:
>>
>>     pi = 3.141519     # etc
>>
>> and make it impossible to override?
>
> No, and it would be a bad thing if that were something a library author
> could forbid.
>
> Python assumes the programmers using it are consenting adults. Doing
> harmful things is difficult but not forbidden.

But surely it can't hurt to ensure certain values can't be changed 
accidentally or maliciously?

Some dynamic languages (OK, I'm thinking of mine) simply allow you to write:

    const pi = 3.14159

Then this can't be changed, because it would be the equivalent of writing:

    3.14159 = 0

What would be the harm in this?

It's a very simple idea, yet many people and languages either don't like 
it or can't grasp it. Not even C has the feature, if you don't count 
using the crude #define for the purpose.

In the case of Python, it could have allowed 'constant folding', so that 
math.pi*2 need not be evaluated at runtime.

(Python however does make it quite difficult to add features like this. 
Mostly because such names are not visible across modules when compiling.

Also it is still possible to write math = some_other_module.)

-- 
Bartc


From ben+python at benfinney.id.au  Sat Nov  7 06:35:05 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 07 Nov 2015 22:35:05 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
Message-ID: <85y4eahwk6.fsf@benfinney.id.au>

Bartc <bc at freeuk.com> writes:

> On 07/11/2015 03:43, Ben Finney wrote:
> > Bartc <bc at freeuk.com> writes:
> >
> >> Is there no way then in Python to declare:
> >>
> >>     pi = 3.141519     # etc
> >>
> >> and make it impossible to override?
> >
> > No, and it would be a bad thing if that were something a library author
> > could forbid.
> >
> > Python assumes the programmers using it are consenting adults. Doing
> > harmful things is difficult but not forbidden.
>
> But surely it can't hurt to ensure certain values can't be changed
> accidentally or maliciously?

The value ?3.141519? (in your example above) can't be changed. That
value will always be exactly the same, as long as the program is
running.

What I think you mean is ?surely it can't hurt to ensure certain names
can never be bound to any value but their initial binding?.

On that I strongly disagree, for the reasons already discussed in this
thread: it arrogates to the library author the power to forbid patching
the library, which cripples extending, debugging, introspection, and a
host of other useful activities.

-- 
 \     ?I object to doing things that computers can do.? ?Olin Shivers |
  `\                                                                   |
_o__)                                                                  |
Ben Finney



From bc at freeuk.com  Sat Nov  7 06:57:16 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 11:57:16 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.104.1446896120.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
Message-ID: <n1koqr$v63$1@dont-email.me>

On 07/11/2015 11:35, Ben Finney wrote:
> Bartc <bc at freeuk.com> writes:
>
>> On 07/11/2015 03:43, Ben Finney wrote:
>>> Bartc <bc at freeuk.com> writes:
>>>
>>>> Is there no way then in Python to declare:
>>>>
>>>>      pi = 3.141519     # etc
>>>>
>>>> and make it impossible to override?
>>>
>>> No, and it would be a bad thing if that were something a library author
>>> could forbid.
>>>
>>> Python assumes the programmers using it are consenting adults. Doing
>>> harmful things is difficult but not forbidden.
>>
>> But surely it can't hurt to ensure certain values can't be changed
>> accidentally or maliciously?
>
> The value ?3.141519? (in your example above) can't be changed. That
> value will always be exactly the same, as long as the program is
> running.
>
> What I think you mean is ?surely it can't hurt to ensure certain names
> can never be bound to any value but their initial binding?.
>
> On that I strongly disagree, for the reasons already discussed in this
> thread: it arrogates to the library author the power to forbid patching
> the library, which cripples extending, debugging, introspection, and a
> host of other useful activities.

Why would it stop introspection?

If the source is available, why would it stop anyone extending a library?

To my mind, Python allows far too much freedom in being able to change 
anything at any time. Imagine if the interfaces to Win32 API or to the 
Linux kernel could be turned upside down from one microsecond to the 
next, while programs are still running.

Take a simple function like thousands of others:

  def dull(x,y,z);
	.....
	.....
99.9999% of the time, the name 'dull' is not going to be bound to 
anything else, and it would just be called like this:

   dull(10,20,30)

Yet Python has to assume 100% of the time that it could have been 
changed. Think of the opportunities for optimising if the probability 
was 0%.

Perhaps if library authors want people tinkering with their code at 
runtime, they should mark it as such ('var', 'volatile' etc). Because 
most of us are quite happy with a boring, static library that is not 
likely to morph into something else!

-- 
Bartc



From ben+python at benfinney.id.au  Sat Nov  7 07:15:32 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 07 Nov 2015 23:15:32 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
Message-ID: <85twoyhuor.fsf@benfinney.id.au>

Bartc <bc at freeuk.com> writes:

> To my mind, Python allows far too much freedom in being able to change
> anything at any time.

You're welcome to that opinion. I don't see you present a reason why it
should affect anyone else's opinion of Python, though.

> Yet Python has to assume 100% of the time that it could have been
> changed. Think of the opportunities for optimising if the probability
> was 0%.

Such a pity that Python is missing all those opportunities for
widespread adoption, by not hewing closer to your preferences.

-- 
 \        ?That's the essence of science: Ask an impertinent question, |
  `\            and you're on the way to the pertinent answer.? ?Jacob |
_o__)                             Bronowski, _The Ascent of Man_, 1973 |
Ben Finney



From bc at freeuk.com  Sat Nov  7 08:00:37 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 13:00:37 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.105.1446898544.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
Message-ID: <n1kshk$brb$1@dont-email.me>

On 07/11/2015 12:15, Ben Finney wrote:
> Bartc <bc at freeuk.com> writes:
>
>> To my mind, Python allows far too much freedom in being able to change
>> anything at any time.
>
> You're welcome to that opinion. I don't see you present a reason why it
> should affect anyone else's opinion of Python, though.

Not just my option. From this 2010 paper for example ('High performance 
implementation of Python for CLI ...' by Antonio Cuni):

"As a language, Python is very hard to implement efficiently: the 
presence of highly dynamic constructs makes static analysis of programs 
extremely difficult, thus preventing ahead of time (AOT) compilers to 
generate efficient target code."

>> Yet Python has to assume 100% of the time that it could have been
>> changed. Think of the opportunities for optimising if the probability
>> was 0%.
>
> Such a pity that Python is missing all those opportunities for
> widespread adoption, by not hewing closer to your preferences.

Plenty of other people working on faster Pythons appear to have trouble 
with its being so dynamic.

(Earlier this year, I was upgrading my own language to be much more 
Python-like in its internal workings. But I gave it up because I was 
losing so many nice features that also made it easy to implement 
efficiently.

As one example of many, named constants (the 'const' feature earlier in 
the thread), were used for 'switch' statements. Without 'const', then I 
couldn't have a fast 'switch'.)

I suppose my coding style is just different from people who write 
Python. When I define a function f(), then it's always going to be 
function f and is never going to change. A call to such a function can 
therefore be streamlined.

If I ever need it to be dynamic, then I use a function pointer:

   g=f

f is still the static function, g is a now a reference to it, and is a 
little slower to call. But the /vast majority/ of function calls are 
going to be static.

-- 
Bartc



From yueyoum at gmail.com  Sat Nov  7 08:23:51 2015
From: yueyoum at gmail.com (yueyoum)
Date: Sat, 07 Nov 2015 21:23:51 +0800
Subject: =?US-ASCII?Q?how_to_copy_PyObject_*_memory_d?=
 =?US-ASCII?Q?ata_to_another_memory_address=3F=0A=0A?=
Message-ID: <1446902615952.dslp41enande24vd1gfb0x4r@android.mail.163.com>

I'm working on a C program that has Python embedded. The host program is multi processes, which communicate via shared memory (mmap). I create a Python object (e.g., PyDict_New) in one process. How can I copy this data to shared memory so that the other process can obtain this data and convert to Python Object? ????????

From lac at openend.se  Sat Nov  7 09:09:35 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 07 Nov 2015 15:09:35 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <n1kshk$brb$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me>
Message-ID: <201511071409.tA7E9ZXL005204@fido.openend.se>

In a message of Sat, 07 Nov 2015 13:00:37 +0000, Bartc writes:

>Not just my option. From this 2010 paper for example ('High performance 
>implementation of Python for CLI ...' by Antonio Cuni):
>
>"As a language, Python is very hard to implement efficiently: the 
>presence of highly dynamic constructs makes static analysis of programs 
>extremely difficult, thus preventing ahead of time (AOT) compilers to 
>generate efficient target code."

Recall that my friend Anto is discussing 'why my phd thesis was hard
stuff, as I did this for PyPy' and not 'Python would be better if it
were easier to write fast compilers for it'. :)

Anto loves the dynamic nature of python.  It just makes pypy hard.

Laura


From marko at pacujo.net  Sat Nov  7 09:23:50 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 07 Nov 2015 16:23:50 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me>
Message-ID: <87d1vlzy4p.fsf@elektro.pacujo.net>

Bartc <bc at freeuk.com>:

> Not just my option. From this 2010 paper for example ('High performance
> implementation of Python for CLI ...' by Antonio Cuni):
>
> "As a language, Python is very hard to implement efficiently: the
> presence of highly dynamic constructs makes static analysis of
> programs extremely difficult, thus preventing ahead of time (AOT)
> compilers to generate efficient target code."

Correct. That's not Python's fault, however. Python should not try to
placate the performance computing people. (Alas, it is now trying to do
just that with the introduction of static typing annotation.)

> Plenty of other people working on faster Pythons appear to have
> trouble with its being so dynamic.

That's, literally, their problem.

> As one example of many, named constants (the 'const' feature earlier
> in the thread), were used for 'switch' statements. Without 'const',
> then I couldn't have a fast 'switch'.)

Fast, fast, fast. We have plenty of fast programming languages. Python
should *not* sacrifice its dynamism (which the fast languages don't
have) for speed. Python is already fast enough for most programming
tasks.

In my work, I currently use bash, Python and C. For many, many tasks,
bash is superior to Python. For others, Python can't compete with C. Yet
the vast gap between bash and C is nicely filled with Python.

Those three golf clubs are all I need in my bag. Java, C#, go, C++ have
great merits. However, I really don't ever miss them.

(The one club I have special sentiments for is Scheme. I don't use it
professionally for, though, because its ecosystem is not quite developed
enough yet.)

> I suppose my coding style is just different from people who write
> Python. When I define a function f(), then it's always going to be
> function f and is never going to change. A call to such a function can
> therefore be streamlined.

Your point of view is really down-to-earth. It's slightly analogous to
protesting against Unicode because you only ever need ASCII.

You would be right in that Python programs hardly ever make use of or
directly depend on the degrees of freedom Python affords. They are used
every here and there, however, and, most imporantly, they make it
possible to define the semantics of the programming language in a sound,
concise manner. That way it is easier to implement Python, learn
Python and use Python correctly.

Imagine there was a national standard that defined that you could only
sell hatchets that split wood in a downward movement. You might argue
that hardly anyone swung a hatchet sideways, and it would be dangerous
anyway. However, that kind of a standard would make it very difficult to
manufacture the simple concept of a hatchet. The contraption would be
expensive, fragile, heavy and difficult to use even for the intended
up-down splitting purpose.

I wouldn't like Python to turn into such a contraption.


Marko


From marko at pacujo.net  Sat Nov  7 09:28:31 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 07 Nov 2015 16:28:31 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
Message-ID: <878u69zxww.fsf@elektro.pacujo.net>

Marko Rauhamaa <marko at pacujo.net>:

> In my work, I currently use bash, Python and C. For many, many tasks,
> bash is superior to Python. For others, Python can't compete with C.
> Yet the vast gap between bash and C is nicely filled with Python.

And, by the way, the introduction of the "const" keyword was maybe the
biggest mistake the C standardizers ever made. It turned out to be about
as useful as a mosquito buzzing at your ear, and equally persistent and
annoying.


Marko


From leonardmesiera at gmail.com  Sat Nov  7 09:44:51 2015
From: leonardmesiera at gmail.com (leonardmesiera at gmail.com)
Date: Sat, 7 Nov 2015 06:44:51 -0800 (PST)
Subject: Guide  in Deskop Application Development in Python for newbies
Message-ID: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>

How do you start building a desktop application in python? I mean where do I start? Besides installing python on your windows what else do I need, and any suggestion on how do I accomplish this project.

Right now I really want to finish this beauty pageant judging system which requires to have a client and a server, client would be for the judges and a server that computes the scores from all the categories, (i do hope you get I want mean by that project). I just finished reading Headfirst Python and I really loving this language, so any help from all the great programmers here would be so great.


From bc at freeuk.com  Sat Nov  7 10:01:34 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 15:01:34 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <878u69zxww.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net>
Message-ID: <n1l3kd$5ma$1@dont-email.me>

On 07/11/2015 14:28, Marko Rauhamaa wrote:
> Marko Rauhamaa <marko at pacujo.net>:
>
>> In my work, I currently use bash, Python and C. For many, many tasks,
>> bash is superior to Python. For others, Python can't compete with C.
>> Yet the vast gap between bash and C is nicely filled with Python.
>
> And, by the way, the introduction of the "const" keyword was maybe the
> biggest mistake the C standardizers ever made. It turned out to be about
> as useful as a mosquito buzzing at your ear, and equally persistent and
> annoying.

(Yes, 'const' in C is a waste of time, and half the people using it 
don't appear to know what it means. Some people also like to use it 
practically everywhere so that you can no longer make out the actual 
code. The version in C++ is a more complicated form even further away 
from what people really want.

Neither have the simplicity of concept of Pascal's 'const', which is 
just a named value. Not a variable that won't change once initialised, 
not a parameter that won't be changed nor any addressable location.)

-- 
Bartc


From bc at freeuk.com  Sat Nov  7 10:19:36 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 15:19:36 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <87d1vlzy4p.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
Message-ID: <n1l4m7$9gr$1@dont-email.me>

On 07/11/2015 14:23, Marko Rauhamaa wrote:
> Bartc <bc at freeuk.com>:

> In my work, I currently use bash, Python and C. For many, many tasks,
> bash is superior to Python. For others, Python can't compete with C. Yet
> the vast gap between bash and C is nicely filled with Python.

The gap between Python and C is still pretty big!

-- 
Bartc


From torriem at gmail.com  Sat Nov  7 10:45:25 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 07 Nov 2015 08:45:25 -0700
Subject: Guide  in Deskop Application Development in Python for newbies
In-Reply-To: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
References: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
Message-ID: <563E1C95.7030609@gmail.com>

On 11/07/2015 07:44 AM, leonardmesiera at gmail.com wrote:
> How do you start building a desktop application in python? I mean
> where do I start? Besides installing python on your windows what else
> do I need, and any suggestion on how do I accomplish this project.
> 
> Right now I really want to finish this beauty pageant judging system
> which requires to have a client and a server, client would be for the
> judges and a server that computes the scores from all the categories,
> (i do hope you get I want mean by that project). I just finished
> reading Headfirst Python and I really loving this language, so any
> help from all the great programmers here would be so great.

Usually one starts by picking a GUI toolkit, of which there are several.
 For example, there's the famous and very nice Qt toolkit (use PyQt or
PySide[1] in Python), there's GTK+ (PyGObject[2]), wxWidgets (wxPython),
Tkinter[3], or Kivy[4].  Of these, Tkinter is baked into Python and
could be a quick way to get started.  Kivy is also very interesting and
potentially can target other platforms like Android.  Personally I
prefer Qt right now.  Many of these toolkits contain tools for
graphically laying out a GUI, although doing layout in code is actually
pretty easy.

Another good option, given your project's architecture, is to build a
frontend that works in the browser. There are numerous web application
frameworks to choose from as well, varying in complexity.

Either way you cut it, you will find a bit of a learning curve, and if
you haven't done GUI development in any language before, there's some
new concepts to understand, like event-driven programming.

Hope this helps. If you search the list archives, you can find many
discussions on what toolkits people like to use and why.

Example links, you can google for many others:
[1] https://wiki.qt.io/PySideDocumentation

http://it.toolbox.com/blogs/enlightenment/pyside-tutorial-using-qt-designer-with-pyside-66012
    https://wiki.qt.io/PySide_Video_Tutorials

[2] https://python-gtk-3-tutorial.readthedocs.org/en/latest/
    https://python-gtk-3-tutorial.readthedocs.org/en/latest/builder.html

[3] http://www.python-course.eu/python_tkinter.php

[4] http://kivy.org/#home


From torriem at gmail.com  Sat Nov  7 10:47:38 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 07 Nov 2015 08:47:38 -0700
Subject: Scipy odeint (LSODA) gives inaccurate results; same code fine
 in MATLAB ode15s/ode23s
In-Reply-To: <n1k73h$agh$1@dont-email.me>
References: <942d2bd0-6322-4733-a6dd-ceeed40368cb@googlegroups.com>
 <n1k73h$agh$1@dont-email.me>
Message-ID: <563E1D1A.7010305@gmail.com>

On 11/06/2015 11:54 PM, Christian Gollwitzer wrote:
> It is very hard to analyze such a problem, unless you also post the 
> Matlab code and plot both solutions into a single graph.

Also he may have a quicker response posting to the scipy list, where
scientists and mathematicians regularly use and talk about scipy:

http://www.scipy.org/scipylib/mailing-lists.html




From invalid at invalid.invalid  Sat Nov  7 11:16:33 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Sat, 7 Nov 2015 16:16:33 +0000 (UTC)
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net>
Message-ID: <n1l851$7e7$2@reader1.panix.com>

On 2015-11-07, Marko Rauhamaa <marko at pacujo.net> wrote:
> Marko Rauhamaa <marko at pacujo.net>:
>
>> In my work, I currently use bash, Python and C. For many, many tasks,
>> bash is superior to Python. For others, Python can't compete with C.
>> Yet the vast gap between bash and C is nicely filled with Python.
>
> And, by the way, the introduction of the "const" keyword was maybe the
> biggest mistake the C standardizers ever made. It turned out to be about
> as useful as a mosquito buzzing at your ear, and equally persistent and
> annoying.

I take it you don't write embedded code that runs from ROM?  I do. The
const keyword is the most valuable addition to the C language since
the function prototype.  Without it, you used to have to jump through
all sorts of hoops to get read-only data placed into read-only memory.

-- 
Grant




From marko at pacujo.net  Sat Nov  7 12:46:23 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 07 Nov 2015 19:46:23 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
Message-ID: <8737whzor4.fsf@elektro.pacujo.net>

Bartc <bc at freeuk.com>:

> (Yes, 'const' in C is a waste of time, and half the people using it
> don't appear to know what it means.

It cannot mean anything meaningful; it's completely useless.

For example, what could one think of standard library functions whose
prototypes are:

   char *strstr(const char *haystack, const char *needle);

   int execve(const char *filename, char *const argv[],
              char *const envp[]);

Ok, enough of C.


Marko


From marko at pacujo.net  Sat Nov  7 13:00:29 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 07 Nov 2015 20:00:29 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
Message-ID: <87y4e9y9j6.fsf@elektro.pacujo.net>

Grant Edwards <invalid at invalid.invalid>:

> I take it you don't write embedded code that runs from ROM? I do. The
> const keyword is the most valuable addition to the C language since
> the function prototype. Without it, you used to have to jump through
> all sorts of hoops to get read-only data placed into read-only memory.

If all you need is a linker directive that places data in a read-only
section, "const" is a very ineffective tool that clutters the code and
forces you to sprinkle type casts around your code.


Marko


From input/ldompeling at casema.nl  Sat Nov  7 16:27:06 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Sat, 07 Nov 2015 21:27:06 GMT
Subject: time module
Message-ID: <K0u%x.70622$_R5.38436@fx07.am1>

hi,

I like to have a function that prints time in seconds.
I am looking for something for example that seconds count from zero.
I search the internet for time module in python but could not found anathing usefull.

Has someone an example for it.

Thanks


-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From cs at zip.com.au  Sat Nov  7 16:47:07 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Sun, 8 Nov 2015 08:47:07 +1100
Subject: time module
In-Reply-To: <K0u%x.70622$_R5.38436@fx07.am1>
References: <K0u%x.70622$_R5.38436@fx07.am1>
Message-ID: <20151107214707.GA89395@cskk.homeip.net>

On 07Nov2015 21:27, input/ldompeling at casema.nl <input/ldompeling at casema.nl> wrote:
>I like to have a function that prints time in seconds.
>I am looking for something for example that seconds count from zero.
>I search the internet for time module in python but could not found anathing usefull.

Here:

  https://docs.python.org/3/library/time.html#time.time

Cheers,
Cameron Simpson <cs at zip.com.au>


From pmiscml at gmail.com  Sat Nov  7 18:00:59 2015
From: pmiscml at gmail.com (Paul Sokolovsky)
Date: Sun, 8 Nov 2015 02:00:59 +0300
Subject: [ANN] MicroPython 1.5
Message-ID: <20151108020059.54a36344@x230>

Hello,

MicroPython is a lean and efficient Python implementation for
microcontrollers, embedded, and mobile systems (which also runs just as
fine on desktops of course).

https://github.com/micropython/micropython

Recent 1.5 release is an important milestone for the project, major
changes including:

1. Advanced REPL support with smart auto-indent and auto-completion for
comfortable interactive typing pf Python code, easily switchable to
paste mode to copy pre-made code snippets.

2. Support for client SSL connections.

3. upip, MicroPython builtin package manager, is now fully standalone
thanks to SSL support.

4. There's new, elaborated API to access hardware features ("machine"
module).

5. There're now 2 well-supported microcontroller boards for
MicroPython, and dozen(s) community-supported ones.

6. MicroPython was selected as one of the languages supported for BBC
micro:bit initiative:
http://ntoll.org/article/story-micropython-on-microbit

7. There's work on native efficient JNI bridge, inspired by Kivy's
PyJNIus module, included into growing Android port.


More detailed changelog for this version is at
https://github.com/micropython/micropython/releases/tag/v1.5

MicroPython supports growing subset of Python3 standard library
(including simplified asyncio package) - not included by default with
an executable, but easily installable per-module using builtin "upip"
package manager:
https://github.com/micropython/micropython-lib


-- 
Best regards,
 Paul                          mailto:pmiscml at gmail.com


From bc at freeuk.com  Sat Nov  7 18:02:24 2015
From: bc at freeuk.com (Bartc)
Date: Sat, 7 Nov 2015 23:02:24 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <1590467.kktH0DaBsW@PointedEars.de>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
Message-ID: <n1lvpv$he1$1@dont-email.me>

On 06/11/2015 22:26, Thomas 'PointedEars' Lahn wrote:
> Bartc wrote:
> ^^^^^
> Please fix.

What's the problem?




From breamoreboy at yahoo.co.uk  Sat Nov  7 18:27:28 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 7 Nov 2015 23:27:28 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <n1lvpv$he1$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me>
Message-ID: <n1m1db$jok$1@ger.gmane.org>

On 07/11/2015 23:02, Bartc wrote:
> On 06/11/2015 22:26, Thomas 'PointedEars' Lahn wrote:
>> Bartc wrote:
>> ^^^^^
>> Please fix.
>
> What's the problem?
>
>

He is the problem.  I assume it's because he thinks he's a dog, cat or 
some other animal.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From ben+python at benfinney.id.au  Sat Nov  7 18:32:33 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 08 Nov 2015 10:32:33 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me>
Message-ID: <85pozlidwu.fsf@benfinney.id.au>

Bartc <bc at freeuk.com> writes:

> On 06/11/2015 22:26, Thomas 'PointedEars' Lahn wrote:
> > Bartc wrote:
> > ^^^^^
> > Please fix.
>
> What's the problem?

As far as I can tell, you're being asked to change that to your ?real?
name, whatever that is supposed to mean.

I recommend you ignore that request; ?Bartc? is fine as a name here,
IMO.

-- 
 \        ?Your [government] representative owes you, not his industry |
  `\   only, but his judgment; and he betrays, instead of serving you, |
_o__)        if he sacrifices it to your opinion.? ?Edmund Burke, 1774 |
Ben Finney



From Cecil at decebal.nl  Sat Nov  7 18:40:11 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Sun, 08 Nov 2015 00:40:11 +0100
Subject: Problems connecting to PostgreSQL
Message-ID: <87wptt5qg4.fsf@Equus.decebal.nl>

I followed http://zetcode.com/db/postgresqlpythontutorial/.

I used:
    sudo -u postgres createuser stressTest
this create the role, but also gave:
    could not change directory to "/root": Permission denied
and I did not get the questions.

Then I used:
    sudo -u postgres createdb stressTest -O stressTest
This gave also:
    could not change directory to "/root": Permission denied

The database is created, but when I execute:
    conn = psycopg2.connect(database = postgres_database, user = 'stressTest')
I get:
    psycopg2.OperationalError: FATAL:  Peer authentication failed for user "stressTest"

What do I need to do to get things working?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From rosuav at gmail.com  Sat Nov  7 18:52:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 8 Nov 2015 10:52:41 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <85pozlidwu.fsf@benfinney.id.au>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
Message-ID: <CAPTjJmpKZPGmxfFahBz1QLO_iZdAp_BPOgk2xAN8D4cgJZAsRw@mail.gmail.com>

On Sun, Nov 8, 2015 at 10:32 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> I recommend you ignore that request; ?Bartc? is fine as a name here,
> IMO.

Given that LARTC means Linux Advanced Routing and Traffic Control, I'm
guessing Bartc is all about *BSD networking? :)

ChrisA


From rosuav at gmail.com  Sat Nov  7 18:54:49 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 8 Nov 2015 10:54:49 +1100
Subject: Problems connecting to PostgreSQL
In-Reply-To: <87wptt5qg4.fsf@Equus.decebal.nl>
References: <87wptt5qg4.fsf@Equus.decebal.nl>
Message-ID: <CAPTjJmoriyHhZRtoi4GFXvzFuHamGfEVbrBJJHfWtgawX2dGvQ@mail.gmail.com>

On Sun, Nov 8, 2015 at 10:40 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> I used:
>     sudo -u postgres createuser stressTest
> this create the role, but also gave:
>     could not change directory to "/root": Permission denied
> and I did not get the questions.
>

You might need to become root before you can become another user - it
depends on your sudoers file. Try this:

sudo sudo -u postgres createuser stressTest

Note that this isn't a Python question, but a PostgreSQL and system
administration one. You may find good results by searching the web for
your issue and omitting all reference to Python.

ChrisA


From torriem at gmail.com  Sat Nov  7 20:50:32 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 07 Nov 2015 18:50:32 -0700
Subject: Guide in Deskop Application Development in Python for newbies
In-Reply-To: <CAJ4+4aqbUbHx1vH2ypotXBd_G7LUHG2vjuGH2_Teg1rC6a1M6g@mail.gmail.com>
References: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
 <563E1C95.7030609@gmail.com>
 <CAJ4+4aqbUbHx1vH2ypotXBd_G7LUHG2vjuGH2_Teg1rC6a1M6g@mail.gmail.com>
Message-ID: <563EAA68.6080906@gmail.com>

On 11/07/2015 12:15 PM, paul.hermeneutic at gmail.com wrote:
> Where would you say that web2py <http://www.web2py.com/> fits into this mix
> of tools?

I am not familiar with it but I know it's supposed to be a lightweight
framework for developing web-based sites and applications.  Could be an
excellent tool for the OP to use to build his user interface.



From phamtony33 at gmail.com  Sat Nov  7 21:11:15 2015
From: phamtony33 at gmail.com (phamtony33 at gmail.com)
Date: Sat, 7 Nov 2015 18:11:15 -0800 (PST)
Subject: Converting a string into a float that includes the negative
Message-ID: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>

I am having issue with converting the string into a float because there is a negative, so only end up with "ValueError: invalid literal for float(): 81.4]"

def contains_words(word,msg):
	if word in msg:
		return true
	else:
		return false
		
def get_tweet(tweet_line):
	part_list = tweet_line.split('\t')
	tweet = part_list[3]
	return tweet

def get_longitude(tweet_line):
	part_list = tweet_line.split('\t')
	gps = part_list[0]
	gps_list = gps.split(', ')
	long = gps_list[1]
	long1 = long[1:]
	longitude = float(long1)
	return longitude

a = get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!")
print a

the answer should be 
get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!") ? -81.4


From contact at stridebird.com  Sat Nov  7 21:39:00 2015
From: contact at stridebird.com (Pete Dowdell)
Date: Sun, 8 Nov 2015 09:39:00 +0700
Subject: Converting a string into a float that includes the negative
In-Reply-To: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>
References: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>
Message-ID: <563EB5C4.4040206@stridebird.com>

On 08/11/15 09:11, phamtony33 at gmail.com wrote:
> I am having issue with converting the string into a float because there is a negative, so only end up with "ValueError: invalid literal for float(): 81.4]"81.4]

The error is right there in the exception: you are trying to cast 
'81.4]' - that's a square bracket in the string.
You are also  removing the negative sign from your number before casting 
with your slice

this will fix it - change line:
long1 = long[1:]
to:
long1 = long[:-1]

test:
 >>> TXT="[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league 
world series!"
 >>> float( TXT.split('\t')[0].split(', ')[1][:-1] )
-81.4

pd


From python at mrabarnett.plus.com  Sat Nov  7 21:40:24 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 8 Nov 2015 02:40:24 +0000
Subject: Converting a string into a float that includes the negative
In-Reply-To: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>
References: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>
Message-ID: <563EB618.8060908@mrabarnett.plus.com>

On 2015-11-08 02:11, phamtony33 at gmail.com wrote:
> I am having issue with converting the string into a float because there is a negative, so only end up with "ValueError: invalid literal for float(): 81.4]"
>
> def contains_words(word,msg):
> 	if word in msg:
> 		return true
> 	else:
> 		return false
> 		
> def get_tweet(tweet_line):
> 	part_list = tweet_line.split('\t')
> 	tweet = part_list[3]
> 	return tweet
>
> def get_longitude(tweet_line):
> 	part_list = tweet_line.split('\t')
> 	gps = part_list[0]
> 	gps_list = gps.split(', ')
> 	long = gps_list[1]
> 	long1 = long[1:]
> 	longitude = float(long1)
> 	return longitude
>
> a = get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!")
> print a
>
> the answer should be
> get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!") ? -81.4
>
You're slicing the wrong end off 'long'.

You have '-81.4]'. You want '-81.4'. You should be doing long[ : -1].



From phamtony33 at gmail.com  Sat Nov  7 21:44:25 2015
From: phamtony33 at gmail.com (phamtony33 at gmail.com)
Date: Sat, 7 Nov 2015 18:44:25 -0800 (PST)
Subject: Converting a string into a float that includes the negative
In-Reply-To: <mailman.116.1446950434.16136.python-list@python.org>
References: <2ced12ff-ae0c-4e86-ac38-357558251e51@googlegroups.com>
 <mailman.116.1446950434.16136.python-list@python.org>
Message-ID: <9c6f5cf7-bb48-4014-8e4b-ab653c56f24c@googlegroups.com>

On Saturday, November 7, 2015 at 9:40:49 PM UTC-5, MRAB wrote:
> On 2015-11-08 02:11, phamtony33 at gmail.com wrote:
> > I am having issue with converting the string into a float because there is a negative, so only end up with "ValueError: invalid literal for float(): 81.4]"
> >
> > def contains_words(word,msg):
> > 	if word in msg:
> > 		return true
> > 	else:
> > 		return false
> > 		
> > def get_tweet(tweet_line):
> > 	part_list = tweet_line.split('\t')
> > 	tweet = part_list[3]
> > 	return tweet
> >
> > def get_longitude(tweet_line):
> > 	part_list = tweet_line.split('\t')
> > 	gps = part_list[0]
> > 	gps_list = gps.split(', ')
> > 	long = gps_list[1]
> > 	long1 = long[1:]
> > 	longitude = float(long1)
> > 	return longitude
> >
> > a = get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!")
> > print a
> >
> > the answer should be
> > get_longitude("[41.3, -81.4]\t6\t2011-08-28 19:02:28\tyay. little league world series!") ? -81.4
> >
> You're slicing the wrong end off 'long'.
> 
> You have '-81.4]'. You want '-81.4'. You should be doing long[ : -1].

Ah! Thank you so much!


From steve at pearwood.info  Sat Nov  7 21:59:16 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 08 Nov 2015 13:59:16 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
Message-ID: <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 02:01 am, Bartc wrote:

> Neither have the simplicity of concept of Pascal's 'const', which is
> just a named value. Not a variable that won't change once initialised,
> not a parameter that won't be changed nor any addressable location.)

Unfortunately the concept of "named value" doesn't match well with Python's
design. That implies a separate compilation step which doesn't fit well
with Python's runtime semantics. Very little happens at compile-time in
Python that *must* happen at compile-time.

I'm also not sure what difference you think there is between "named value"
and "variable that won't change once initialised".

Python has a convention for "constants" -- all UPPERCASE names. The fact
that the convention exists is enough to prove that the concept
of "constant" is a useful one. The difference between Python's
pseudo-constants and (say) Pascal's actual constants is that in Python, the
burden of ensuring that neither you, nor any of the libraries you call,
modifies the "constant" falls on you, the user, whereas in Pascal the
compiler or interpreter performs that checking for you.

Besides, the Python convention is honoured more in theory than in practice.
We have math.pi, not math.PI.



-- 
Steven



From steve at pearwood.info  Sat Nov  7 22:07:15 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 08 Nov 2015 14:07:15 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <8737whzor4.fsf@elektro.pacujo.net>
Message-ID: <563ebc64$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 04:46 am, Marko Rauhamaa wrote:

> Bartc <bc at freeuk.com>:
> 
>> (Yes, 'const' in C is a waste of time, and half the people using it
>> don't appear to know what it means.
> 
> It cannot mean anything meaningful; it's completely useless.
> 
> For example, what could one think of standard library functions whose
> prototypes are:
> 
>    char *strstr(const char *haystack, const char *needle);
> 
>    int execve(const char *filename, char *const argv[],
>               char *const envp[]);

Surely that is obvious? I don't speak much C, but I would expect that inside
the functions, const parameters can be read, but not assigned to. "*const"
is a mystery to me though.


> Ok, enough of C.

Amen to that.

If I had a dollar for every crime against computing committed because of C,
or enabled due to C's design decisions, I would be rich beyond the dreams
of avarice.

Fortunately, C is not the only other computer language, and we are by no
means limited to the two choices of the status quo (no constants in Python)
and what C does.



-- 
Steven



From adiamond1978 at gmail.com  Sat Nov  7 22:13:12 2015
From: adiamond1978 at gmail.com (Andrew Diamond)
Date: Sat, 7 Nov 2015 19:13:12 -0800 (PST)
Subject: [Ubuntu] PyQt5
Message-ID: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>

Hi!

I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.

Running Ubuntu 15.10, and installed pyqt5 via:

sudo apt-get install python3-pyqt5
sudo apt-get install qtcreator

Thank you in advance for any assistance!


From invalid at invalid.invalid  Sat Nov  7 22:31:59 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Sun, 8 Nov 2015 03:31:59 +0000 (UTC)
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net>
Message-ID: <n1mfnf$md6$2@reader1.panix.com>

On 2015-11-07, Marko Rauhamaa <marko at pacujo.net> wrote:
> Grant Edwards <invalid at invalid.invalid>:
>
>> I take it you don't write embedded code that runs from ROM? I do. The
>> const keyword is the most valuable addition to the C language since
>> the function prototype. Without it, you used to have to jump through
>> all sorts of hoops to get read-only data placed into read-only memory.
>
> If all you need is a linker directive that places data in a read-only
> section, "const" is a very ineffective tool that clutters the code and
> forces you to sprinkle type casts around your code.

But it allows the compiler to warn you if you pass a pointer to a
read-only data to a function that expects a pointer to writable data.

For those of us who occasionally make mistakes, such compiler warnings
are very useful.

-- 
Grant



From steve at pearwood.info  Sat Nov  7 22:50:04 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 08 Nov 2015 14:50:04 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
Message-ID: <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 01:23 am, Marko Rauhamaa wrote:

> Bartc <bc at freeuk.com>:
> 
>> Not just my option. From this 2010 paper for example ('High performance
>> implementation of Python for CLI ...' by Antonio Cuni):
>>
>> "As a language, Python is very hard to implement efficiently: the
>> presence of highly dynamic constructs makes static analysis of
>> programs extremely difficult, thus preventing ahead of time (AOT)
>> compilers to generate efficient target code."
> 
> Correct. That's not Python's fault, however. Python should not try to
> placate the performance computing people. (Alas, it is now trying to do
> just that with the introduction of static typing annotation.)

That is factually incorrect.

The motive behind the introduction of typing annotations is not "speed",
but "correctness". Guido has expressed skepticism that typing annotations
can be used to improve the speed of Python programs, and has suggested that
the future of optimization is JIT compilers like PyPy rather than static
compilers like Nuitka.

[Aside: I have to disagree with Guido's thoughts on compilers. Even if JIT
compilers are ultimately faster for long-running code, they don't help much
for short-running code, and surely there is a lot of low-hanging fruit that
an optimizing compiler can perform. Victor Skinner is experimenting with a
version of CPython which, among other things, detects when built-ins have
not been modified, and can inline them for speed.]

If type annotations lead to faster code, that's a bonus, but it isn't why
they are being added to the language. They are added to improve correctness
and documentation, to enable type-checks to be performed by linters and
compile-time type-checkers.


>> Plenty of other people working on faster Pythons appear to have
>> trouble with its being so dynamic.
> 
> That's, literally, their problem.
> 
>> As one example of many, named constants (the 'const' feature earlier
>> in the thread), were used for 'switch' statements. Without 'const',
>> then I couldn't have a fast 'switch'.)
> 
> Fast, fast, fast. We have plenty of fast programming languages.

Yeah, but most of them suck. Why can't we have a fast programming language
that is as nice to use as Python? Why can't Python be fast?



> Python 
> should *not* sacrifice its dynamism (which the fast languages don't
> have) for speed. Python is already fast enough for most programming
> tasks.

Well, I don't know about anyone else, but I personally always want my
scripts and programs to run slower. I can't tell you how annoyed I was when
new-style classes became as fast or faster than old-style classes.

*wink*


[...]
>> I suppose my coding style is just different from people who write
>> Python. When I define a function f(), then it's always going to be
>> function f and is never going to change. A call to such a function can
>> therefore be streamlined.
> 
> Your point of view is really down-to-earth. It's slightly analogous to
> protesting against Unicode because you only ever need ASCII.

I don't think so, but in any case, Bart is *way* oversimplifying the
potential optimizations available. Function inlining depends on the
function being small enough that inlining it does more good than harm, but
it doesn't require that f never changes.

Perhaps Laura can confirm this, but I understand that PyPy can inline
functions. Simplified:

The compiler builds a fast path and a slow path, and a guard. If the
function is the one you expect, the interpreter takes the fast path, which
includes the inlined function. But if the function has been rebound, the
guard triggers, and the interpreter takes the slow path, which follows the
slow, dynamic implementation. In pseudo-code:

def spam():
    result = eggs(x)

will compile as if it were written like this:

def spam():
    if eggs is EXPECTED_EGGS:
        # inline code
        do_this()
        do_that()
        result = another_thing(x)
    else:
        result = eggs(x)


The compiler manages all the book-keeping for you, automatically, and as
functions grow and shrink in complexity, it will automatically decide which
ones can be inlined and which cannot. You write the simplest, most obvious
code which is easy to maintain, and the compiler managers the ugly
optimizations.


> You would be right in that Python programs hardly ever make use of or
> directly depend on the degrees of freedom Python affords.

That's certainly true. Every Python program pays a significant speed penalty
(perhaps as much as 10 x slower than it need be) for features which are
used by probably less than 1% of code.

The choice is not between "dynamic language" and "fast language". You can
have both. Smalltalk proves it. Javascript proves it. You just need smarter
compilers which can optimize the usual, non-dynamic cases while still
allowing dynamic code to work.

We often say that the reason Python is anything up to a factor of 100 times
slower than languages like Java is because Python is so dynamic, but that's
not true. Python is so slow because *Python compilers aren't smart enough*.
CPython is a relatively simple reference implementation which applies
hardly any optimizations.

Even such simple things as constant folding are slightly controversial! If
you go back to older versions of Python, code like this:

    x = 1 + 1

actually performed the addition at runtime, instead of being compiled to:

    x = 2

Believe it or not, even something as simple as that remains controversial,
with some folks (including Guido) expressing doubt that constant-folding is
worthwhile.

But PyPy proves that Python compilers can be smarter, and optimize more,
without sacrificing dynamicism.


> They are used 
> every here and there, however, and, most imporantly, they make it
> possible to define the semantics of the programming language in a sound,
> concise manner. That way it is easier to implement Python, learn
> Python and use Python correctly.
> 
> Imagine there was a national standard that defined that you could only
> sell hatchets that split wood in a downward movement. You might argue
> that hardly anyone swung a hatchet sideways, and it would be dangerous
> anyway. However, that kind of a standard would make it very difficult to
> manufacture the simple concept of a hatchet. The contraption would be
> expensive, fragile, heavy and difficult to use even for the intended
> up-down splitting purpose.

I don't think that's a good analogy.

A better analogy is, imagine that Ford built a car that allowed you to swap
out the radio, the doors, the tyres, even the engine, while the car was
moving. You could unplug the engine while driving down the road, and plug
in a new one, and the car would just keep going. As a consequence, the car
is significantly bigger and slower than most other cars, and occasionally
it is useful (when you get a flat tyre, you don't have to stop, you just
swap into place a new tyre and keep going) but generally it's not used much
(who swaps out the seat that they are sitting on?).

Ford call this car "Python".


> I wouldn't like Python to turn into such a contraption.




-- 
Steven



From vincent.vande.vyvre at telenet.be  Sun Nov  8 00:36:26 2015
From: vincent.vande.vyvre at telenet.be (Vincent Vande Vyvre)
Date: Sun, 8 Nov 2015 06:36:26 +0100
Subject: [Ubuntu] PyQt5
In-Reply-To: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
Message-ID: <563EDF5A.6040403@telenet.be>

Le 08/11/2015 04:13, Andrew Diamond a ?crit :
> Hi!
>
> I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.
>
> Running Ubuntu 15.10, and installed pyqt5 via:
>
> sudo apt-get install python3-pyqt5
> sudo apt-get install qtcreator
>
> Thank you in advance for any assistance!
Works fine for me on 15.04.

I've tested the first example with the menuBar.

Have you a message into the terminal? Maybe an error?

Vincent


From flebber.crue at gmail.com  Sun Nov  8 00:55:32 2015
From: flebber.crue at gmail.com (Sayth Renshaw)
Date: Sat, 7 Nov 2015 21:55:32 -0800 (PST)
Subject: Is there an archive of the gohlke python binaries on windows
Message-ID: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>

Just wondering if there is an archive mirror for these binaries available. i was looking for lxml 3.4.1 and the current version is the latest on the page at 3.4.4 being on windows I cannot build it.

http://www.lfd.uci.edu/~gohlke/pythonlibs/

Thanks

Sayth


From random832 at fastmail.com  Sun Nov  8 01:29:11 2015
From: random832 at fastmail.com (Random832)
Date: Sun, 08 Nov 2015 01:29:11 -0500
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <8737whzor4.fsf@elektro.pacujo.net>
 <563ebc64$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <m2r3k1m2bs.fsf@fastmail.com>

Steven D'Aprano <steve at pearwood.info> writes:
> Surely that is obvious? I don't speak much C, but I would expect that inside
> the functions, const parameters can be read, but not assigned to. "*const"
> is a mystery to me though.

There's a program (and now a website) called cdecl that can decode these:

char *const envp[]
declare envp as array of const pointer to char

In other words, the pointers in the array are const, but the array
itself (which is really a pointer, and it's generally regarded as
nonsense to make const first-level function arguments anyway, but enough
of that) is not, nor are the characters that the pointers point to.

There are various reasons I don't fully understand and are beyond the
scope of this argument regarding why it's not possible to assign a
pointer-to-pointer-to-char to a pointer-to-pointer-to-const-char, so the
argument isn't declared with the latter.

Unfortunately, while it handles simple function arguments, it (the
version on the website at least) apparently can't handle named or const
function arguments, otherwise you could paste the whole thing.



From marko at pacujo.net  Sun Nov  8 02:45:55 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 09:45:55 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net> <n1mfnf$md6$2@reader1.panix.com>
Message-ID: <87d1vlx7bg.fsf@elektro.pacujo.net>

Grant Edwards <invalid at invalid.invalid>:

> On 2015-11-07, Marko Rauhamaa <marko at pacujo.net> wrote:
>> "const" is a very ineffective tool that clutters the code and forces
>> you to sprinkle type casts around your code.
>
> But it allows the compiler to warn you if you pass a pointer to a
> read-only data to a function that expects a pointer to writable data.

Unfortunately, it doesn't:

========================================================================
#include <stdio.h>
#include <string.h>

int main()
{
    const char name[] = "Tom";
    char *p = strstr(name, "Tom");
    strcpy(p, "Bob");
    printf("name = %s\n", name);
    return 0;
}
========================================================================

    $ cc -o prog prog.c
    $ ./prog
    Bob

No warning.

Point is, the consequences of "proper" use of const are so annoying even
standard library functions would rather grossly abuse it than tolerate
compiler warnings everywhere.


Marko


From auriocus at gmx.de  Sun Nov  8 03:00:27 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sun, 8 Nov 2015 09:00:27 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <87d1vlx7bg.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net> <n1mfnf$md6$2@reader1.panix.com>
 <87d1vlx7bg.fsf@elektro.pacujo.net>
Message-ID: <n1mvak$660$1@dont-email.me>

Am 08.11.15 um 08:45 schrieb Marko Rauhamaa:
> Grant Edwards <invalid at invalid.invalid>:
>
>> On 2015-11-07, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> "const" is a very ineffective tool that clutters the code and forces
>>> you to sprinkle type casts around your code.
>>
>> But it allows the compiler to warn you if you pass a pointer to a
>> read-only data to a function that expects a pointer to writable data.
>
> Unfortunately, it doesn't:
>
> ========================================================================
> #include <stdio.h>
> #include <string.h>
>
> int main()
> {
>      const char name[] = "Tom";
>      char *p = strstr(name, "Tom");
>      strcpy(p, "Bob");
>      printf("name = %s\n", name);
>      return 0;
> }
> ========================================================================
>
>      $ cc -o prog prog.c
>      $ ./prog
>      Bob
>
> No warning.
>

That is strange. In C, I can see thet problem here, because it is 
impossible to define a const correct strstr. But in C++ I have expected 
that according to the overload, the const version of strstr would be 
selected (http://www.cplusplus.com/reference/cstring/strstr/ ) . Still:

apfelkiste:Tests chris$ cat prog.cpp
#include <cstdio>
#include <cstring>

int main()
{
     const char name[] = "Tom";
     char *p = strstr(name, "Tom"); // this line should be an error
     strcpy(p, "Bob");
     printf("name = %s\n", name);
     return 0;
}

apfelkiste:Tests chris$ g++ -Wall prog.cpp
apfelkiste:Tests chris$ ./a.out
Bus error: 10

It segfaults because on OSX, const can be stored in write-only memory.

apfelkiste:Tests chris$ g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr 
--with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin12.6.0
Thread model: posix


	Christian


From no.email at nospam.invalid  Sun Nov  8 03:08:28 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Sun, 08 Nov 2015 00:08:28 -0800
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net> <n1mfnf$md6$2@reader1.panix.com>
 <87d1vlx7bg.fsf@elektro.pacujo.net>
Message-ID: <87h9kwvrpf.fsf@nightsong.com>

Marko Rauhamaa <marko at pacujo.net> writes:
> Point is, the consequences of "proper" use of const are so annoying even
> standard library functions would rather grossly abuse it than tolerate
> compiler warnings everywhere.

I'm not sure what the C standard says about that example, but C++ is
much stricter about those conversions, and g++ does flag an error if
you compile that code with it.


From kwpolska at gmail.com  Sun Nov  8 03:36:38 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Sun, 8 Nov 2015 09:36:38 +0100
Subject: Problems connecting to PostgreSQL
In-Reply-To: <87wptt5qg4.fsf@Equus.decebal.nl>
References: <87wptt5qg4.fsf@Equus.decebal.nl>
Message-ID: <CAMw+j7Ju5PiPuwczE5OS9iBSuP33XJQjoZ11rLhSiBQjMNZGJg@mail.gmail.com>

On 8 November 2015 at 00:40, Cecil Westerhof <Cecil at decebal.nl> wrote:
> I followed http://zetcode.com/db/postgresqlpythontutorial/.
>
> I used:
>     sudo -u postgres createuser stressTest
> this create the role, but also gave:
>     could not change directory to "/root": Permission denied
> and I did not get the questions.

This is not an error, just a warning ? and it comes from sudo,
postgres doesn?t care. To silence it, you need to work from a
different directory than /root.  The commands actually worked just
fine.

> Then I used:
>     sudo -u postgres createdb stressTest -O stressTest
> This gave also:
>     could not change directory to "/root": Permission denied
>
> The database is created, but when I execute:
>     conn = psycopg2.connect(database = postgres_database, user = 'stressTest')
> I get:
>     psycopg2.OperationalError: FATAL:  Peer authentication failed for user "stressTest"
>
> What do I need to do to get things working?

You need to configure your PostgreSQL database to use md5
authentication, and set a password for your user.

    # cd /
    # sudo -u postgres psql
    postgres=# ALTER ROLE stressTest WITH PASSWORD 'swordfish';
    postgres=# \q
    # vim /var/lib/postgres/data/pg_hba.conf

Change host settings to look like this:
    # IPv4 local connections:
    host    all             all             127.0.0.1/32            md5
    # IPv6 local connections:
    host    all             all             ::1/128                 md5

Then you can connect using:

    conn = psycopg2.connect(database='stressTest', user='stressTest',
password='swordfish', host='localhost')

Documentation:
http://www.postgresql.org/docs/current/static/auth-pg-hba-conf.html
http://www.postgresql.org/docs/current/static/auth-methods.html
http://www.postgresql.org/docs/current/static/sql-alterrole.html

(basically, the default peer authentication checks your Unix user name
to see if it matches 'stressTest', and fails)

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From kwpolska at gmail.com  Sun Nov  8 04:22:01 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Sun, 8 Nov 2015 10:22:01 +0100
Subject: Guide in Deskop Application Development in Python for newbies
In-Reply-To: <563EAA68.6080906@gmail.com>
References: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
 <563E1C95.7030609@gmail.com>
 <CAJ4+4aqbUbHx1vH2ypotXBd_G7LUHG2vjuGH2_Teg1rC6a1M6g@mail.gmail.com>
 <563EAA68.6080906@gmail.com>
Message-ID: <CAMw+j7JLN2PNU4rsK7122WZTAiPUxTac-1fHNvymQ=4Ec3s6Nw@mail.gmail.com>

On 7 November 2015 at 15:44,  <leonardmesiera at gmail.com> wrote:
> How do you start building a desktop application in python? I mean where do I start? Besides installing python on your windows what else do I need, and any suggestion on how do I accomplish this project.
>
> Right now I really want to finish this beauty pageant judging system which requires to have a client and a server, client would be for the judges and a server that computes the scores from all the categories, (i do hope you get I want mean by that project). I just finished reading Headfirst Python and I really loving this language, so any help from all the great programmers here would be so great.
> --
> https://mail.python.org/mailman/listinfo/python-list

This project requires two very different components, or one monolithic server.

The first one is the server. It basically needs to talk to clients
(via HTTP) and to a database. This is a trivial app to write in your
favorite web framework, eg. Django [0]. Come up with a good database
structure (read the excellent tutorial and documentation, should get
you there), write some models. But you can?t write your views just
yet. Because the views you write depend strictly on the client.

For the client, you basically have two choices:
(a) write a web application in Django;
(b) use a GUI framework and make a standalone desktop application.

If you choose option (a), you need to learn HTML/CSS and write the
views for your Django application (or use a ready-made front-end
framework, eg. Bootstrap [1]). This is the simplest choice, and it
takes a lot of work away from you. Your users will use their favorite
web browser to access the voting system, log in, and make their votes,
and there is no special setup for them (apart from giving them
credentials to access your app). Your Django views will use the
built-in Django templating, forms, and is relatively simple to do
(might even be doable in a weekend).

Route (b) is much more complicated. To follow this route, you need to
pick a GUI framework. There are also multiple options, I personally
recommend PySide, but you could also try wxWidgets, pygobject or kivy.
The web app side of things will require serializing data to JSON and
writing a RESTful API, but there are ready-made solutions for many web
frameworks [2].
But most of those come with a catch: they usually make you produce
ugly code, because they are wrappers around ugly C++ APIs. And then
you need to write code to talk to your HTTP server. You can?t use the
beautiful requests library, because it will block ? so there?s more
work ahead, unless you want your app to be unresponsive every time you
talk to the server. For example, in Qt, you would need to use Qt
networking capabilities (which work asynchronously within the event
loop), or some other implementation that you can use asynchronously
(eg. Twisted, but then you lock yourself to Python 2, which is bad, or
threading, which has its limitations?)
And then you need to distribute your app to your users. Which is
already hard, because you need to coordinate Python, your GUI
framework, and your app. Are your users on Windows, Linux, or OS X? If
you have at least one person on a platform, you will need some sort of
testing environment?

And no matter which route you choose, you can?t do much without a
Linux server, so there?s more learning to do.

Sadly, developing big things is hard and requires a lot of knowledge ?
especially if you?re a one-man-band.
Here?s a short list of skills you need, with a subjectively suggested
implementation and ease of implementation:

* understanding of the HTTP protocol (*)
* web application development (Django *)
* database schema writing (planning out the structure + Django ORM **)
* app server setup (uWSGI + nginx + Linux ***)
* database setup (PostgreSQL *** or something simpler[3])
* Route A:
  * HTML/CSS skills; a front-end framework (Bootstrap **)
* Route B:
  * RESTful APIs (Django REST Framework ***/***** if you use OAuth)
  * GUI framework (PyQt ****)
  * talking to your server from within the framework (****/*****)

[0]: https://www.djangoproject.com/
[1]: http://getbootstrap.com/
[2]: http://www.django-rest-framework.org/
[3]: If this is going to be VERY small, you could go with a sqlite
database, which requires zero setup, but which is not suited for
anything more serious.

Other learning materials:

https://uwsgi-docs.readthedocs.org/en/latest/tutorials/Django_and_nginx.html
http://www.fullstackpython.com/
http://deploypython.com/

On 8 November 2015 at 02:50, Michael Torrie <torriem at gmail.com> wrote:
> On 11/07/2015 12:15 PM, paul.hermeneutic at gmail.com wrote:
>> Where would you say that web2py <http://www.web2py.com/> fits into this mix
>> of tools?
>
> I am not familiar with it but I know it's supposed to be a lightweight
> framework for developing web-based sites and applications.  Could be an
> excellent tool for the OP to use to build his user interface.
>
> --
> https://mail.python.org/mailman/listinfo/python-list

web2py is weird, Django is more fun.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From kwpolska at gmail.com  Sun Nov  8 04:43:41 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Sun, 8 Nov 2015 10:43:41 +0100
Subject: Is there an archive of the gohlke python binaries on windows
In-Reply-To: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
References: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
Message-ID: <CAMw+j7KhV8CweRXV_R8_NNTcFYsa9VZTpjOrVTz8EuvGLc7Fzw@mail.gmail.com>

On 8 November 2015 at 06:55, Sayth Renshaw <flebber.crue at gmail.com> wrote:
> Just wondering if there is an archive mirror for these binaries available. i was looking for lxml 3.4.1 and the current version is the latest on the page at 3.4.4 being on windows I cannot build it.
>
> http://www.lfd.uci.edu/~gohlke/pythonlibs/
>
> Thanks
>
> Sayth
> --
> https://mail.python.org/mailman/listinfo/python-list

Why do you need an old version? There should be no reason to use an
old version?  Why can?t you use lxml 3.4.4?

If you are a fan of old software, you are probably on Python 2.x, too,
and you can get a binary from here:
https://pypi.python.org/pypi/lxml/3.4.1

Also, those binaries are built by someone USING Windows. You can
certainly build C extensions, if you install Visual Studio in the
correct version.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From marko at pacujo.net  Sun Nov  8 04:44:01 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 11:44:01 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <878u68ygf2.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> On Sun, 8 Nov 2015 01:23 am, Marko Rauhamaa wrote:
>> Correct. That's not Python's fault, however. Python should not try to
>> placate the performance computing people. (Alas, it is now trying to
>> do just that with the introduction of static typing annotation.)
>
> That is factually incorrect.
>
> The motive behind the introduction of typing annotations is not "speed",
> but "correctness".

Oh, then I'm even more disappointed with type annotation.


Marko


From marko at pacujo.net  Sun Nov  8 04:49:12 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 11:49:12 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net> <n1mfnf$md6$2@reader1.panix.com>
 <87d1vlx7bg.fsf@elektro.pacujo.net> <87h9kwvrpf.fsf@nightsong.com>
Message-ID: <874mgwyg6f.fsf@elektro.pacujo.net>

Paul Rubin <no.email at nospam.invalid>:

> Marko Rauhamaa <marko at pacujo.net> writes:
>> Point is, the consequences of "proper" use of const are so annoying even
>> standard library functions would rather grossly abuse it than tolerate
>> compiler warnings everywhere.
>
> I'm not sure what the C standard says about that example, but C++ is
> much stricter about those conversions, [...]

C++ gets const even more wrong than C, and const is the least of C++'s
problems.


Marko


From lac at openend.se  Sun Nov  8 05:20:12 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 08 Nov 2015 11:20:12 +0100
Subject: [Ubuntu] PyQt5
In-Reply-To: <563EDF5A.6040403@telenet.be>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <563EDF5A.6040403@telenet.be>
Message-ID: <201511081020.tA8AKCn5029601@fido.openend.se>

In a message of Sun, 08 Nov 2015 06:36:26 +0100, Vincent Vande Vyvre writes:
>Le 08/11/2015 04:13, Andrew Diamond a ?crit :
>> Hi!
>>
>> I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.
>>
>> Running Ubuntu 15.10, and installed pyqt5 via:
>>
>> sudo apt-get install python3-pyqt5
>> sudo apt-get install qtcreator
>>
>> Thank you in advance for any assistance!
>Works fine for me on 15.04.
>
>I've tested the first example with the menuBar.
>
>Have you a message into the terminal? Maybe an error?
>
>Vincent

A suggestion:

When I get the 'it locks up when I want to quit' behaviour
in PyQt4 it is because I have messed up something with my threading.
PyQt4 wants there to be one, main control thread (that handles, among
other things, shutting down) and lots of worker threads which do the
gui-stuff, i.e. all the work that the program really needs to do.

If you manage to structure things so that your control ends up in
a worker thread, then when it is told to quit, your app sits around
and waits for the main control thread to come back and deal with things,
but your main control thread is dead, and therefore isn't coming.

I assume you can get problems like this with Qt5 as well.

Did quitting work properly with the earlier exercises of this tutorial,
or did you try to start learning from the middle?

Laura


From flebber.crue at gmail.com  Sun Nov  8 05:21:40 2015
From: flebber.crue at gmail.com (Sayth Renshaw)
Date: Sun, 8 Nov 2015 02:21:40 -0800 (PST)
Subject: Is there an archive of the gohlke python binaries on windows
In-Reply-To: <mailman.121.1446975829.16136.python-list@python.org>
References: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
 <mailman.121.1446975829.16136.python-list@python.org>
Message-ID: <7a919b0a-205b-49c7-8a36-903f63be3497@googlegroups.com>

On Sunday, 8 November 2015 20:44:02 UTC+11, Chris Warrick  wrote:
> On 8 November 2015 at 06:55, Sayth Renshaw <flebber.crue at gmail.com> wrote:
> > Just wondering if there is an archive mirror for these binaries available. i was looking for lxml 3.4.1 and the current version is the latest on the page at 3.4.4 being on windows I cannot build it.
> >
> > http://www.lfd.uci.edu/~gohlke/pythonlibs/
> >
> > Thanks
> >
> > Sayth
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Why do you need an old version? There should be no reason to use an
> old version...  Why can't you use lxml 3.4.4?
> 
> If you are a fan of old software, you are probably on Python 2.x, too,
> and you can get a binary from here:
> https://pypi.python.org/pypi/lxml/3.4.1
> 
> Also, those binaries are built by someone USING Windows. You can
> certainly build C extensions, if you install Visual Studio in the
> correct version.
> 
> -- 
> Chris Warrick <https://chriswarrick.com/>
> PGP: 5EAAEA16

I want to use lxml 3.4.1 because it is the required version in portia current version

Sayth


From input/ldompeling at casema.nl  Sun Nov  8 05:25:28 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Sun, 08 Nov 2015 10:25:28 GMT
Subject: time module
References: <mailman.114.1446941944.16136.python-list@python.org>
Message-ID: <sqF%x.23626$mP1.4332@fx24.ams1>

>  Ambiguous requirement: any normal counter starts from zero... But what
> "zero" represents may differ... Seconds since Jan 1 1970? Seconds since
> midnight? Seconds since start of program?

Thanks for the reply

Yes, I would like seconds since start of program.
Can I not doing something like time()=0 only this gives an error.

Thanks
------------------------------------------------------------------------
In reply to "Dennis Lee Bieber" who wrote the following:

> On Sat, 07 Nov 2015 21:27:06 GMT, input/ldompeling at casema.nl declaimed the
> following:
> 
> > hi,
> > 
> > I like to have a function that prints time in seconds.
> > I am looking for something for example that seconds count from zero.
> > I search the internet for time module in python but could not found anathing
> > usefull.
> > 
> 
>  Ambiguous requirement: any normal counter starts from zero... But what
> "zero" represents may differ... Seconds since Jan 1 1970? Seconds since
> midnight? Seconds since start of program?
> 
> > > > import time
> > > > t0 = time.time()
> > > > t0
> 1446941608.052
> > > > t0 / 60.0
> 24115693.467533335
> > > > t0 / 60.0 / 60.0
> 401928.22445888893
> > > > t0 / 60.0 / 60.0 / 24.0
> 16747.009352453704
> > > > t0 / 60.0 / 60.0 / 24.0 / 365.25
> 45.850812737724034
> > > > 
> 
>  Almost 46 years worth of seconds.
> 
> > > > tStart = time.time()
> > > > for x in range(10):
> ...  time.sleep(x)
> ...  print time.time() - tStart
> ...  
> 36.5020000935
> 37.5040001869
> 39.5090000629
> 42.5099999905
> 46.5170001984
> 51.5190000534
> 57.5200002193
> 64.5210001469
> 72.5230000019
> 81.5230000019
> > > > 
> 
> Okay, I'm not the fastest typist (35 seconds from tStart to finishing the
> loop code)
> --
>  Wulfraed                 Dennis Lee Bieber         AF6VN
>     wlfraed at ix.netcom.com    HTTP://wlfraed.home.netcom.com/




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From lac at openend.se  Sun Nov  8 05:30:30 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 08 Nov 2015 11:30:30 +0100
Subject: Is there an archive of the gohlke python binaries on windows
In-Reply-To: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
References: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
Message-ID: <201511081030.tA8AUU9D030343@fido.openend.se>

In a message of Sat, 07 Nov 2015 21:55:32 -0800, Sayth Renshaw writes:
>Just wondering if there is an archive mirror for these binaries available. i was looking for lxml 3.4.1 and the current version is the latest on the page at 3.4.4 being on windows I cannot build it.
>
>http://www.lfd.uci.edu/~gohlke/pythonlibs/
>
>Thanks
>
>Sayth

https://pypi.python.org/pypi/lxml/3.4.1

Laura


From bc at freeuk.com  Sun Nov  8 05:40:19 2015
From: bc at freeuk.com (Bartc)
Date: Sun, 8 Nov 2015 10:40:19 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1n8mc$33l$1@dont-email.me>

On 08/11/2015 02:59, Steven D'Aprano wrote:
> On Sun, 8 Nov 2015 02:01 am, Bartc wrote:
>
>> Neither have the simplicity of concept of Pascal's 'const', which is
>> just a named value. Not a variable that won't change once initialised,
>> not a parameter that won't be changed nor any addressable location.)
>
> Unfortunately the concept of "named value" doesn't match well with Python's
> design. That implies a separate compilation step which doesn't fit well
> with Python's runtime semantics. Very little happens at compile-time in
> Python that *must* happen at compile-time.
>
> I'm also not sure what difference you think there is between "named value"
> and "variable that won't change once initialised".

This is what I mean about people not understanding it!

In NASM terms, a named constant is like:

     daysinweek   equ   7           ; definition

     mov rax, daysinweek            ; using it, as immediate value
     mov rbx, daysinweek*2          ; an a 'compile-term' expression
;   mov daysinweek,8               ; can't be done! Illegal syntax

While a 'const' variable, C style, might be:

     segment .rodata
monthsinyear:                      ; definition
     dd 12

     mov rax,[monthsinyear]         ; using it, as memory access
;   mov rbx,[monthsinyear*10]      ; can't be done!
     mov [monthsinyear],6           ; can be done, but might give memory
                                    ; access errors if actually stored in
                                    ; protected memory. Usually in C,
                                    ; it isn't

So in native code, a named value is not much different to a literal such 
as 7, or 3.14159. (But unlike C's #define, the name is a proper symbol 
with normal scope rules, and a type).

The distinction at the machine level can be blurred with some 
instructions sets where there might not be an immediate data option for 
some data widths or types. Also where named constants are applied to 
things such as strings, which necessarily use storage.

In the language however, you will not be able to use the named constant 
as an lvalue, and you will usually be able to use it for compile-time 
constant folding and for dimensioning fixed-bound arrays and such.)

> Python has a convention for "constants" -- all UPPERCASE names. The fact
> that the convention exists is enough to prove that the concept
> of "constant" is a useful one. The difference between Python's
> pseudo-constants and (say) Pascal's actual constants is that in Python, the
> burden of ensuring that neither you, nor any of the libraries you call,
> modifies the "constant" falls on you, the user, whereas in Pascal the
> compiler or interpreter performs that checking for you.

With a real named constant the check can always be done at compile-time. 
Unless you have a pure interpreter or some more elaborate way of 
executing source code.

(In the case of Python, the main obstacle is that a constant name from 
inside an imported module is not visible when this module is compiled to 
byte-code. So it has to assume it can be anything.)

-- 
BartC


From marko at pacujo.net  Sun Nov  8 06:02:20 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 13:02:20 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me>
Message-ID: <87ziyowy83.fsf@elektro.pacujo.net>

Bartc <bc at freeuk.com>:

> (In the case of Python, the main obstacle is that a constant name from
> inside an imported module is not visible when this module is compiled
> to byte-code. So it has to assume it can be anything.)

Which it can.

Optimizing for naive floating-point constants could be done but has
barely any significance in most Python code. Numeric computations are
carried out in separate native plugins.

Most Python code deals with encapsulated objects whose innards are
hidden and whose only semantics are defined by the access methods. New
implementations or derived objects can be plugged in transparently.

A case in point are the so-called file-like objects. They are a simple,
elegant concept. I can come up with new file-like objects without any
common pedigree with some predefined classes and incorporate them with a
lot of utility classes.

That elegant dynamism comes at a cost: method lookup is not a constant
memory offset. Rather, it is a dictionary lookup.


Marko


From marko at pacujo.net  Sun Nov  8 06:05:02 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 13:05:02 +0200
Subject: time module
References: <mailman.114.1446941944.16136.python-list@python.org>
 <sqF%x.23626$mP1.4332@fx24.ams1>
Message-ID: <87vb9cwy3l.fsf@elektro.pacujo.net>

input/ldompeling at casema.nl:

> Yes, I would like seconds since start of program.
> Can I not doing something like time()=0 only this gives an error.

Here:

    class MyReckoning:
        def __init__(self):
            self.the_beginning = time.time()

        def time(self):
            return time.time() - self.the_beginning

    reckoning = MyReckoning()
    print(reckoning.time())


Marko


From bc at freeuk.com  Sun Nov  8 06:06:27 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 11:06:27 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1na7c$86c$1@dont-email.me>

On 08/11/2015 03:50, Steven D'Aprano wrote:
> On Sun, 8 Nov 2015 01:23 am, Marko Rauhamaa wrote:

>> Your point of view is really down-to-earth. It's slightly analogous to
>> protesting against Unicode because you only ever need ASCII.
>
> I don't think so, but in any case, Bart is *way* oversimplifying the
> potential optimizations available. Function inlining depends on the
> function being small enough that inlining it does more good than harm, but
> it doesn't require that f never changes.

I didn't really have function in-lining in mind (although once you are 
sure a specific function will always be called, that is a possibility 
for the compiler).

There are plenty of optimisations available if you know you are calling 
a function, and the compiler can 'see' the source code:

* You don't need to check that 'f' in 'f(a,b,c)' is a function; it will be.

* You will know whether the number of arguments provided is correct or 
not, and make adjustments at compile-time if not

* Where keyword parameters are used, this can also all be sorted out at 
compile-time, rather than at runtime

* (And does Python still need to do a lookup for the name 'f'? I don't 
know; the CPython sources are hard to follow. But in my interpreters, 
this is never necessary at runtime.)

However, most functions will not be visible to the compiler because they 
are in imported modules. A certain amount of work can be done when a 
module is loaded, but this now starts to get complicated.

> Even such simple things as constant folding are slightly controversial! If
> you go back to older versions of Python, code like this:
>
>      x = 1 + 1
>
> actually performed the addition at runtime, instead of being compiled to:
>
>      x = 2
>
> Believe it or not, even something as simple as that remains controversial,

Actually, it's not so simple! If floating point expressions are 
involved, the results can be different between compiler and runtime, if 
the compilation is done on a separate machine. But this is only a 
problem is byte-code is distributed rather than sources.

-- 
BartC


From steve at pearwood.info  Sun Nov  8 06:11:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 08 Nov 2015 22:11:20 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <878u68ygf2.fsf@elektro.pacujo.net>
Message-ID: <563f2dda$0$1602$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 08:44 pm, Marko Rauhamaa wrote:

> Steven D'Aprano <steve at pearwood.info>:
> 
>> On Sun, 8 Nov 2015 01:23 am, Marko Rauhamaa wrote:
>>> Correct. That's not Python's fault, however. Python should not try to
>>> placate the performance computing people. (Alas, it is now trying to
>>> do just that with the introduction of static typing annotation.)
>>
>> That is factually incorrect.
>>
>> The motive behind the introduction of typing annotations is not "speed",
>> but "correctness".
> 
> Oh, then I'm even more disappointed with type annotation.


/me does a double-take


Wait a minute, you've just spent a bunch of paragraphs explaining that
Python is plenty fast enough (for you), that you don't need it to be
faster. Okay. Now you're saying that you're *even more* disappointed that
type annotations will be used to make code *more correct* and *less buggy*.

So... you have no need for Python to be fast, and even less need for Python
code to be correct...

Or perhaps you mean that you don't need help writing correct code, because
your code is perfect...

It is moments like this I wonder if you are trolling.


-- 
Steven



From bc at freeuk.com  Sun Nov  8 06:19:50 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 11:19:50 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <87ziyowy83.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
Message-ID: <n1nb0f$atn$1@dont-email.me>

On 08/11/2015 11:02, Marko Rauhamaa wrote:
> Bartc <bc at freeuk.com>:
>
>> (In the case of Python, the main obstacle is that a constant name from
>> inside an imported module is not visible when this module is compiled
>> to byte-code. So it has to assume it can be anything.)
>
> Which it can.
....
> That elegant dynamism comes at a cost: method lookup is not a constant
> memory offset. Rather, it is a dictionary lookup.

I've never understood why this seems to be necessary in Python. Why do 
names have to be looked up? (I'm assuming this is searching by name in 
some sort of table.)

When a module is compiled, while the compiler can't see the definitions 
inside the imported modules, it /will/ know all the names that appear in 
this module, so it can organise them into fixed tables. Then the names 
can be referred to by index. (I think LOAD_FAST does this.)

Or is eval() the culprit here by making most optimisations impossible?

-- 
Bartc


From marko at pacujo.net  Sun Nov  8 06:25:21 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 13:25:21 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <563ec66d$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <878u68ygf2.fsf@elektro.pacujo.net>
 <563f2dda$0$1602$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87r3k0wx5q.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> So... you have no need for Python to be fast, and even less need for
> Python code to be correct...

Correct. If I didn't think so, I'd still be using Java instead of
Python.

> Or perhaps you mean that you don't need help writing correct code,
> because your code is perfect...

Python's noise-free syntax does more for code quality than compile-time
type checking.


Marko


From steve at pearwood.info  Sun Nov  8 06:30:03 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 08 Nov 2015 22:30:03 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me>
Message-ID: <563f323d$0$1586$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 09:40 pm, Bartc wrote:

> On 08/11/2015 02:59, Steven D'Aprano wrote:
>> On Sun, 8 Nov 2015 02:01 am, Bartc wrote:
>>
>>> Neither have the simplicity of concept of Pascal's 'const', which is
>>> just a named value. Not a variable that won't change once initialised,
>>> not a parameter that won't be changed nor any addressable location.)
>>
>> Unfortunately the concept of "named value" doesn't match well with
>> Python's design. That implies a separate compilation step which doesn't
>> fit well with Python's runtime semantics. Very little happens at
>> compile-time in Python that *must* happen at compile-time.
>>
>> I'm also not sure what difference you think there is between "named
>> value" and "variable that won't change once initialised".
> 
> This is what I mean about people not understanding it!

I'm pretty sure I understand what *I* mean by constant, and what Pascal
means by it, and why the Pascal meaning doesn't quite match what Python can
do. I'm not sure I understand what *you* mean, or why you think a "variable
that won't change" isn't good enough.


> In NASM terms, a named constant is like:
> 
>      daysinweek   equ   7           ; definition
> 
>      mov rax, daysinweek            ; using it, as immediate value
>      mov rbx, daysinweek*2          ; an a 'compile-term' expression
> ;   mov daysinweek,8               ; can't be done! Illegal syntax

In pseudo-Python, we have:

const daysinweek = 7  # let's just pretend it exists
x = daysinweek + 1  # this is fine
daysinweek = 8  # an error

Apart from the difference between compile-time and run-time, why would this
not be satisfactory?

Oh, and just to satisfy Ben, the determined monkey-patcher can write:

globals()['daysinweek'] = 8

if they really want to defeat the compiler. The idea is to avoid
*accidental* bindings.



> While a 'const' variable, C style, might be:
[...]

Why does your C code look like assembler?


> So in native code, a named value is not much different to a literal such
> as 7, or 3.14159. (But unlike C's #define, the name is a proper symbol
> with normal scope rules, and a type).
> 
> The distinction at the machine level can be blurred with some
> instructions sets where there might not be an immediate data option for
> some data widths or types. Also where named constants are applied to
> things such as strings, which necessarily use storage.

I am not interested in the limitations of low-level machine languages. They
have very little to say about what Python can or should do.


> In the language however, you will not be able to use the named constant
> as an lvalue, and you will usually be able to use it for compile-time
> constant folding and for dimensioning fixed-bound arrays and such.)

We're talking about Python, and how the concept of "const" might apply to a
Python-like language. Compile-time constant folding is not part of it,
because the constant itself might not exist at compile-time:

const START = time.time()

Fixed-bound arrays are irrelevant (neither lists nor arrays are
fixed-bounds; tuples are, but they are constructed at runtime, not compile
time). 


>> Python has a convention for "constants" -- all UPPERCASE names. The fact
>> that the convention exists is enough to prove that the concept
>> of "constant" is a useful one. The difference between Python's
>> pseudo-constants and (say) Pascal's actual constants is that in Python,
>> the burden of ensuring that neither you, nor any of the libraries you
>> call, modifies the "constant" falls on you, the user, whereas in Pascal
>> the compiler or interpreter performs that checking for you.
> 
> With a real named constant the check can always be done at compile-time.
> Unless you have a pure interpreter or some more elaborate way of
> executing source code.

Python has such a "more elaborate way" of executing source code:


exec("""
if condition:
    import time
    const START = time.time()
    x = START + 1
""")




-- 
Steven



From marko at pacujo.net  Sun Nov  8 06:50:35 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 13:50:35 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
Message-ID: <87mvuowvzo.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> On 08/11/2015 11:02, Marko Rauhamaa wrote:
>> That elegant dynamism comes at a cost: method lookup is not a constant
>> memory offset. Rather, it is a dictionary lookup.
>
> I've never understood why this seems to be necessary in Python. Why do
> names have to be looked up? (I'm assuming this is searching by name in
> some sort of table.)
>
> When a module is compiled, while the compiler can't see the
> definitions inside the imported modules, it /will/ know all the names
> that appear in this module, so it can organise them into fixed tables.
> Then the names can be referred to by index. (I think LOAD_FAST does
> this.)

Modules are not the issue. Barely any functions are invoked from the
modules. Rather, almost all invocations are object methods. (Of course,
modules are objects, too.) Methods belong to objects that can be
literally anything.

Consider, for example,

    shutil.copyfileobj(src, dst[, length])

The shutil module has absolutely no idea what kind of objects src and
dst are. An example program:

========================================================================
import shutil

class Source:
    def __init__(self):
        self.remaining = "hello world"

    def read(self, count):
        if count <= 0:
            return ""
        chunk, self.remaining = self.remaining[:count], self.remaining[count:]
        return chunk

class Dest:
    def write(self, stuff):
        print("<{}>".format(stuff))

shutil.copyfileobj(Source(), Dest())
========================================================================


Marko


From bc at freeuk.com  Sun Nov  8 07:24:19 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 12:24:19 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <563f323d$0$1586$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me>
 <563f323d$0$1586$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1nepc$nuq$1@dont-email.me>

On 08/11/2015 11:30, Steven D'Aprano wrote:
> On Sun, 8 Nov 2015 09:40 pm, Bartc wrote:

>> This is what I mean about people not understanding it!
>
> I'm pretty sure I understand what *I* mean by constant, and what Pascal
> means by it, and why the Pascal meaning doesn't quite match what Python can
> do. I'm not sure I understand what *you* mean, or why you think a "variable
> that won't change" isn't good enough.

I showed you what I mean. A named constant is a just a value - with a 
label. That value doesn't need to be stored in a 'box' anywhere, in 
exactly the same manner as values that can be written to (and therefore 
at risk of being overwritten).

But let me turn it around: why is it so important to use variables for 
this purpose?

>> In NASM terms, a named constant is like:
>>
>>       daysinweek   equ   7           ; definition
>>
>>       mov rax, daysinweek            ; using it, as immediate value
>>       mov rbx, daysinweek*2          ; an a 'compile-term' expression
>> ;   mov daysinweek,8               ; can't be done! Illegal syntax
>
> In pseudo-Python, we have:
>
> const daysinweek = 7  # let's just pretend it exists
> x = daysinweek + 1  # this is fine
> daysinweek = 8  # an error
>
> Apart from the difference between compile-time and run-time, why would this
> not be satisfactory?

If that's all that's possible, that it will have to do. And might solve 
the OP's problem.

But for a true named constant, there is no actual assignment. It really 
is not necessary. 'daysinweek' is just a synonym for '7'.

>
>> While a 'const' variable, C style, might be:
> [...]
>
> Why does your C code look like assembler?

I mean the 'const' is C style. The assembly code is to highlight the 
difference between what C calls a const, and what I call a named constant.

> I am not interested in the limitations of low-level machine languages. They
> have very little to say about what Python can or should do.

OK, let's take a higher level one:

  const a = 2
  var   b = 3

  c = a+b

which might generate a byte-code like this:

       push_ci   2
       push_m    [b]
       add
       pop_m     [c]

Now apply this to Python byte-code. Can you not see the advantage of not 
having to deal with variable names, reference counts, garbage collection 
and all that?

I don't know what you had in mind for implementing the pretend 'const' 
in your Python example above. But if it takes the form of an extra 
runtime attribute, then all variable accesses will be slowed then if it 
is has to be checked for every assignment, and 'const' names won't be 
any faster.

>> In the language however, you will not be able to use the named constant
>> as an lvalue, and you will usually be able to use it for compile-time
>> constant folding and for dimensioning fixed-bound arrays and such.)
>
> We're talking about Python, and how the concept of "const" might apply to a
> Python-like language. Compile-time constant folding is not part of it,
> because the constant itself might not exist at compile-time:
>
> const START = time.time()

You're thinking in C terms again. The C 'const' really means 'read-only' 
and applies to ordinary variables. It has nothing to do with my named 
constants which are always known at compile-time

(That's if the definitions are visible. If not, then they will be known 
at the time the module they're in is compiled. Linking these is one of 
the problems in a Python implementation.)

> Fixed-bound arrays are irrelevant (neither lists nor arrays are
> fixed-bounds; tuples are, but they are constructed at runtime, not compile
> time).

Think of a possible 'switch' statement then, and the values for its case 
labels.

> Python has such a "more elaborate way" of executing source code:
>
>
> exec("""
> if condition:
>      import time
>      const START = time.time()
>      x = START + 1
> """)

(1) That is not a const but a variable with a read-only attribute. The 
expression after the "=" should itself be a constant expression or a 
literal value. (No reason why Python shouldn't have such an attribute, 
but that's different from what I'm talking about.)

(2) I assume that the contents of the string passed to exec() are first 
compiled to byte-code. Then that's the same as a normal compile, with 
the same problems of visibility and imparting its constant definitions 
to code that is compiled separately. (If the use 'exec' is more subtle, 
then we might as well give up!)

-- 
BartC


From rosuav at gmail.com  Sun Nov  8 07:28:00 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 8 Nov 2015 23:28:00 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n1nb0f$atn$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
Message-ID: <CAPTjJmpidWBB3KLyP_WDZvKi7i8HXYieT0eUhxqPFDmp0UU2vw@mail.gmail.com>

On Sun, Nov 8, 2015 at 10:19 PM, BartC <bc at freeuk.com> wrote:
> I've never understood why this seems to be necessary in Python. Why do names
> have to be looked up? (I'm assuming this is searching by name in some sort
> of table.)

Yes, if by "searching" you include hash-table lookup. A CPython
dictionary is a *highly* optimized data structure, specifically
because it's used virtually everywhere (I understand Lua's "table"
type has similar optimizations for the same reason). In the common
case, where your names come from literal text in the module, the
strings used for the lookup will be interned constants, and their
hashes will have been precalculated and stored, so the lookup is
pretty easy. So it's a constant-time operation, and while that
constant may be larger than a simple offset-and-fetch, it's still
pretty fast in the overall scheme of things.

ChrisA


From benak.tomas at gmail.com  Sun Nov  8 07:34:22 2015
From: benak.tomas at gmail.com (=?UTF-8?B?VG9tw6HFoSBCZcWIw6Fr?=)
Date: Sun, 8 Nov 2015 13:34:22 +0100
Subject: Python 3.5.0: python.exe is not a valid Windows 32 application
Message-ID: <CAD=sbih_g063v0oZhW8QFR_z47Biju39iKTkgxBW3BAg3vMmzA@mail.gmail.com>

Hi,

I have downloaded the Python 3.5.0 installer for x86 (
https://www.python.org/ftp/python/3.5.0/python-3.5.0.exe) and have
installed it on my Windows XP SP3. The installer run to a successful end,
but when I try to run python.exe, it ends with an error saying that
python.exe is not a valid Windows 32 application.
Is this a bug? Is my Windows XP a problem? Should I try another release of
Python? Could you provide me with the link?
Thank you.

Best regards
Tom?? Be??k


From bc at freeuk.com  Sun Nov  8 07:39:50 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 12:39:50 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <87mvuowvzo.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
Message-ID: <n1nfmf$qta$1@dont-email.me>

On 08/11/2015 11:50, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:
>
>> On 08/11/2015 11:02, Marko Rauhamaa wrote:
>>> That elegant dynamism comes at a cost: method lookup is not a constant
>>> memory offset. Rather, it is a dictionary lookup.
>>
>> I've never understood why this seems to be necessary in Python. Why do
>> names have to be looked up? (I'm assuming this is searching by name in
>> some sort of table.)
>>
>> When a module is compiled, while the compiler can't see the
>> definitions inside the imported modules, it /will/ know all the names
>> that appear in this module, so it can organise them into fixed tables.
>> Then the names can be referred to by index. (I think LOAD_FAST does
>> this.)
>
> Modules are not the issue. Barely any functions are invoked from the
> modules. Rather, almost all invocations are object methods. (Of course,
> modules are objects, too.) Methods belong to objects that can be
> literally anything.
>
> Consider, for example,
>
>      shutil.copyfileobj(src, dst[, length])
>
> The shutil module has absolutely no idea what kind of objects src and
> dst are. An example program:
>
> ========================================================================
> import shutil
>
> class Source:
>      def __init__(self):
>          self.remaining = "hello world"
>
>      def read(self, count):
>          if count <= 0:
>              return ""
>          chunk, self.remaining = self.remaining[:count], self.remaining[count:]
>          return chunk
>
> class Dest:
>      def write(self, stuff):
>          print("<{}>".format(stuff))
>
> shutil.copyfileobj(Source(), Dest())
> ========================================================================

OK, so here, it is necessary to resolve "copyfileobj" by seeing if 
"shutil" is something that contains a name "copyfileobj" that happens to 
be a method.

Is this the lookup you're talking about, and is it done using the actual 
string "copyfileobj"? If so, does it need to be done every single time 
this line is executed? It would extraordinarily inefficient if that was 
the case.

-- 
Bartc


From marko at pacujo.net  Sun Nov  8 07:43:37 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 14:43:37 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
 <n1nfmf$qta$1@dont-email.me>
Message-ID: <87io5cwtja.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> On 08/11/2015 11:50, Marko Rauhamaa wrote:
>> ========================================================================
>> import shutil
>>
>> class Source:
>>      def __init__(self):
>>          self.remaining = "hello world"
>>
>>      def read(self, count):
>>          if count <= 0:
>>              return ""
>>          chunk, self.remaining = self.remaining[:count], self.remaining[count:]
>>          return chunk
>>
>> class Dest:
>>      def write(self, stuff):
>>          print("<{}>".format(stuff))
>>
>> shutil.copyfileobj(Source(), Dest())
>> ========================================================================
>
> OK, so here, it is necessary to resolve "copyfileobj" by seeing if
> "shutil" is something that contains a name "copyfileobj" that happens
> to be a method.
>
> Is this the lookup you're talking about, and is it done using the
> actual string "copyfileobj"? If so, does it need to be done every
> single time this line is executed? It would extraordinarily
> inefficient if that was the case.

No, what I'm talking about is that copyfileobj calls src.read() and
dst.write() without having any idea what kinds of objects src and dst
are. Thus, it will be difficult for a performance optimizer to get rid
of the dictionary lookups.


Marko


From bc at freeuk.com  Sun Nov  8 08:42:51 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 13:42:51 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <87io5cwtja.fsf@elektro.pacujo.net>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
 <n1nfmf$qta$1@dont-email.me> <87io5cwtja.fsf@elektro.pacujo.net>
Message-ID: <n1njcj$8jf$1@dont-email.me>

On 08/11/2015 12:43, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:
>
>> On 08/11/2015 11:50, Marko Rauhamaa wrote:
>>> ========================================================================
>>> import shutil
>>>
>>> class Source:
>>>       def __init__(self):
>>>           self.remaining = "hello world"
>>>
>>>       def read(self, count):
>>>           if count <= 0:
>>>               return ""
>>>           chunk, self.remaining = self.remaining[:count], self.remaining[count:]
>>>           return chunk
>>>
>>> class Dest:
>>>       def write(self, stuff):
>>>           print("<{}>".format(stuff))
>>>
>>> shutil.copyfileobj(Source(), Dest())
>>> ========================================================================
>>
>> OK, so here, it is necessary to resolve "copyfileobj" by seeing if
>> "shutil" is something that contains a name "copyfileobj" that happens
>> to be a method.
>>
>> Is this the lookup you're talking about, and is it done using the
>> actual string "copyfileobj"? If so, does it need to be done every
>> single time this line is executed? It would extraordinarily
>> inefficient if that was the case.
>
> No, what I'm talking about is that copyfileobj calls src.read() and
> dst.write() without having any idea what kinds of objects src and dst
> are. Thus, it will be difficult for a performance optimizer to get rid
> of the dictionary lookups.

Sorry, you'll have to assume I'm very stupid.

What exactly is being looked up, and in what?

 From what I can understand in your example:

* You are calling shutil.copyfileobj with two arguments, which happen to 
be instances of classes Source and Dest.

* Let's say these are known as src and dst inside .copyfileobj.

* .copyfileobj then calls methods src.read() dst.write().

* Each of these method calls has the form A.B() which seems to me to be 
little different from shutil.copyfileobj().

So to get back to what I was saying, does this lookup involving 
searching for method B in object A, and if so, does it actually do a 
search by name?

(Someone mentioned a precalculated hash, of "A", or of "src" or "dst", 
use used, but still, it's looking something up in a table, and a hash 
table lookup I believe still requires an string compare to check if 
you've got the right entry.)

-- 
Bartc


From ainoags02 at outlook.es  Sun Nov  8 09:07:24 2015
From: ainoags02 at outlook.es (=?utf-8?B?QWlub2EgR3V0acOpcnJleiBTdcOhcmV6?=)
Date: Sun, 8 Nov 2015 14:07:24 +0000
Subject: No subject
Message-ID: <SNT406-EAS79923C8C808114EBDA8ACDD5160@phx.gbl>

it doesn?twork the entry to Python.






Enviado desde Correo de Windows

From marko at pacujo.net  Sun Nov  8 09:33:00 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 08 Nov 2015 16:33:00 +0200
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
 <n1nfmf$qta$1@dont-email.me> <87io5cwtja.fsf@elektro.pacujo.net>
 <n1njcj$8jf$1@dont-email.me>
Message-ID: <87egg0wogz.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

>>> On 08/11/2015 11:50, Marko Rauhamaa wrote:
>>>> ========================================================================
>>>> import shutil
>>>>
>>>> class Source:
>>>>       def __init__(self):
>>>>           self.remaining = "hello world"
>>>>
>>>>       def read(self, count):
>>>>           if count <= 0:
>>>>               return ""
>>>>           chunk, self.remaining = self.remaining[:count], self.remaining[count:]
>>>>           return chunk
>>>>
>>>> class Dest:
>>>>       def write(self, stuff):
>>>>           print("<{}>".format(stuff))
>>>>
>>>> shutil.copyfileobj(Source(), Dest())
>>>> ========================================================================
>
> What exactly is being looked up, and in what?
>
> [...]
>
> So to get back to what I was saying, does this lookup involving
> searching for method B in object A, and if so, does it actually do a
> search by name?

Yes, finding Source.read and Dest.write involves hash table lookups. In
fact, it's even a bit more involved: each method fetch consists of *two*
hash table lookups. First you have to check if the object has a match in
its individual lookup table and next if there is a match in the class's
lookup table.


Marko


From rosuav at gmail.com  Sun Nov  8 10:11:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 02:11:26 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n1njcj$8jf$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
 <n1nfmf$qta$1@dont-email.me> <87io5cwtja.fsf@elektro.pacujo.net>
 <n1njcj$8jf$1@dont-email.me>
Message-ID: <CAPTjJmr8F6E5Cj7ayDk47-jzb70Zge7kNTrXAyLGMofGfwoh7g@mail.gmail.com>

On Mon, Nov 9, 2015 at 12:42 AM, BartC <bc at freeuk.com> wrote:
> Sorry, you'll have to assume I'm very stupid.
>
> What exactly is being looked up, and in what?
>
> From what I can understand in your example:
>
> * You are calling shutil.copyfileobj with two arguments, which happen to be
> instances of classes Source and Dest.
>
> * Let's say these are known as src and dst inside .copyfileobj.
>
> * .copyfileobj then calls methods src.read() dst.write().
>
> * Each of these method calls has the form A.B() which seems to me to be
> little different from shutil.copyfileobj().
>
> So to get back to what I was saying, does this lookup involving searching
> for method B in object A, and if so, does it actually do a search by name?
>
> (Someone mentioned a precalculated hash, of "A", or of "src" or "dst", use
> used, but still, it's looking something up in a table, and a hash table
> lookup I believe still requires an string compare to check if you've got the
> right entry.)

The lookups I'm talking about happen pretty much anywhere. Firstly,
this function:

def f():
    shutil.copyfileobj(src, dst)

looks up the global name 'shutil' (that's one dict lookup - module
globals are a dictionary), then performs an attribute lookup on the
resulting object with the name 'copyfileobj', then looks up the two
global names 'src' and 'dst'.

In fact[1], those strings can be found in f.__code__.co_names, and the
byte-code identifies them by their indices in that tuple. These are
str objects (note that this means they can be any legal Unicode
string; "?????.???????????(???, ???)" is just as valid), and their
hashes will normally be precomputed to save time. Now, things are a
bit different with function-locals; the compiler always knows which
names they are, and it can compile things differently. Compare:

def f(src):
    shutil.copyfileobj(src, dst)

Instead of looking up a global name 'src', this now looks up a local
name. They're identified by slot positions, so the compiler simply
knows that "src" is in slot #0, and instead of looking anything up,
simply says "load the thing in slot #0". There can also be other
levels of indirection, such as __getattr__ and __getattribute__, which
affect how stuff gets looked up. But otherwise, name lookups generally
involve poking a dict with a string and taking what comes back
(possibly replacing KeyError with NameError or AttributeError as the
case may be).

ChrisA

[1] Assuming we're using CPython, or something which uses the same
byte-code; this is NOT a language requirement - none of this is.


From torriem at gmail.com  Sun Nov  8 10:59:59 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 08 Nov 2015 08:59:59 -0700
Subject: Question about math.pi is mutable
In-Reply-To: <n1nb0f$atn$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
Message-ID: <563F717F.3010007@gmail.com>

On 11/08/2015 04:19 AM, BartC wrote:

>> That elegant dynamism comes at a cost: method lookup is not a constant
>> memory offset. Rather, it is a dictionary lookup.
> 
> I've never understood why this seems to be necessary in Python. Why do 
> names have to be looked up? (I'm assuming this is searching by name in 
> some sort of table.)
> 
> When a module is compiled, while the compiler can't see the definitions 
> inside the imported modules, it /will/ know all the names that appear in 
> this module, so it can organise them into fixed tables. Then the names 
> can be referred to by index. (I think LOAD_FAST does this.)
> 
> Or is eval() the culprit here by making most optimisations impossible?

Perhaps I'm misunderstanding what you're saying, here, but the reason a
lookup has to be performed is because python variables are not like C
variables. They aren't boxes per se.  They are names bound to objects.
so doing something like

a += 1

Actually assigns the name "a" to an entirely new object than the one it
had before, which, from the interpreters point of view, is in an
entirely different memory location.

Whereas in C, a variable is a box that's always at the same location, so
the name is simply not important, and at runtime variables have no
names.  Python is not like this.  names are important at runtime.  There
may be certain circumstances where the Python compiler could optimize
certain types of variable access (say if the variable was bound to
integers only) into C-style variables under the hood. But I don't think
the benefit would be that great.





From adiamond1978 at gmail.com  Sun Nov  8 11:03:44 2015
From: adiamond1978 at gmail.com (Andrew Diamond)
Date: Sun, 8 Nov 2015 08:03:44 -0800 (PST)
Subject: [Ubuntu] PyQt5
In-Reply-To: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
Message-ID: <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>

On Saturday, November 7, 2015 at 10:13:25 PM UTC-5, Andrew Diamond wrote:
> Hi!
> 
> I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.
> 
> Running Ubuntu 15.10, and installed pyqt5 via:
> 
> sudo apt-get install python3-pyqt5
> sudo apt-get install qtcreator
> 
> Thank you in advance for any assistance!

I just read somewhere that the issue could be because I was trying to run these examples from within Idle.  However, when I try to run them from the terminal, I run into another snag:

andrew at andrew-Satellite-P755:~/Programming/Python$ python tut8.py 
Traceback (most recent call last):
  File "tut8.py", line 16, in <module>
    from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication
ImportError: No module named PyQt5.QtWidgets

...a path issue?


From rosuav at gmail.com  Sun Nov  8 11:10:25 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 03:10:25 +1100
Subject: Python 3.5.0: python.exe is not a valid Windows 32 application
In-Reply-To: <CAD=sbih_g063v0oZhW8QFR_z47Biju39iKTkgxBW3BAg3vMmzA@mail.gmail.com>
References: <CAD=sbih_g063v0oZhW8QFR_z47Biju39iKTkgxBW3BAg3vMmzA@mail.gmail.com>
Message-ID: <CAPTjJmoZ96oOrO2ck+aqdybk2gsB3FSqvj=w_YgvhCX38MOVUg@mail.gmail.com>

On Sun, Nov 8, 2015 at 11:34 PM, Tom?? Be??k <benak.tomas at gmail.com> wrote:
> I have downloaded the Python 3.5.0 installer for x86 (
> https://www.python.org/ftp/python/3.5.0/python-3.5.0.exe) and have
> installed it on my Windows XP SP3. The installer run to a successful end,
> but when I try to run python.exe, it ends with an error saying that
> python.exe is not a valid Windows 32 application.
> Is this a bug? Is my Windows XP a problem? Should I try another release of
> Python? Could you provide me with the link?

Your Windows XP is a problem. You have a couple of options: either
upgrade to Vista/7/8/10, or downgrade your Python to 3.4, which does
support XP.

There is also a bug, which is that the installer appears to run
successfully. When Python 3.5.1 is released (currently scheduled for
early December), the installer should detect XP early on and save you
the confusion.

ChrisA


From lac at openend.se  Sun Nov  8 11:15:18 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 08 Nov 2015 17:15:18 +0100
Subject: Python 3.5.0: python.exe is not a valid Windows 32 application
In-Reply-To: <CAD=sbih_g063v0oZhW8QFR_z47Biju39iKTkgxBW3BAg3vMmzA@mail.gmail.com>
References: <CAD=sbih_g063v0oZhW8QFR_z47Biju39iKTkgxBW3BAg3vMmzA@mail.gmail.com>
Message-ID: <201511081615.tA8GFItB025380@fido.openend.se>

In a message of Sun, 08 Nov 2015 13:34:22 +0100, Tom?? Be??k writes:
>Hi,
>
>I have downloaded the Python 3.5.0 installer for x86 (
>https://www.python.org/ftp/python/3.5.0/python-3.5.0.exe) and have
>installed it on my Windows XP SP3. The installer run to a successful end,
>but when I try to run python.exe, it ends with an error saying that
>python.exe is not a valid Windows 32 application.
>Is this a bug? Is my Windows XP a problem? Should I try another release of
>Python? Could you provide me with the link?
>Thank you.
>
>Best regards
>Tom?? Be??k

This is an XP problem.  XP is not supported for 3.5 and later.
The latest you can run is 3.4.3
https://www.python.org/downloads/release/python-343/

Laura


From rosuav at gmail.com  Sun Nov  8 11:17:02 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 03:17:02 +1100
Subject: how to copy PyObject * memory data to another memory address?
In-Reply-To: <1446902615952.dslp41enande24vd1gfb0x4r@android.mail.163.com>
References: <1446902615952.dslp41enande24vd1gfb0x4r@android.mail.163.com>
Message-ID: <CAPTjJmr795k4OyJVEou78kjVcnQ-3KgzM_Ztr6raCfdA1t-icw@mail.gmail.com>

On Sun, Nov 8, 2015 at 12:23 AM, yueyoum <yueyoum at gmail.com> wrote:
> I'm working on a C program that has Python embedded. The host program is multi processes, which communicate via shared memory (mmap). I create a Python object (e.g., PyDict_New) in one process. How can I copy this data to shared memory so that the other process can obtain this data and convert to Python Object? ????????
>

The best way to do this would be to serialize it in some format - JSON
is a good choice, if all your data can fit into that format;
otherwise, consider the Pickle format. Python objects consist of lots
of references to other objects, so it's difficult to transfer them
from one to another as they are. JSON will serve you well.

ChrisA


From rosuav at gmail.com  Sun Nov  8 11:22:07 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 03:22:07 +1100
Subject: [Ubuntu] PyQt5
In-Reply-To: <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
Message-ID: <CAPTjJmr6g6D4vWARZPOMVoC9z_6Q8qbOOHh8o6_+MLtx7Bq89A@mail.gmail.com>

On Mon, Nov 9, 2015 at 3:03 AM, Andrew Diamond <adiamond1978 at gmail.com> wrote:
> On Saturday, November 7, 2015 at 10:13:25 PM UTC-5, Andrew Diamond wrote:
>> Hi!
>>
>> I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.
>>
>> Running Ubuntu 15.10, and installed pyqt5 via:
>>
>> sudo apt-get install python3-pyqt5
>> sudo apt-get install qtcreator
>>
>> Thank you in advance for any assistance!
>
> I just read somewhere that the issue could be because I was trying to run these examples from within Idle.  However, when I try to run them from the terminal, I run into another snag:
>
> andrew at andrew-Satellite-P755:~/Programming/Python$ python tut8.py
> Traceback (most recent call last):
>   File "tut8.py", line 16, in <module>
>     from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication
> ImportError: No module named PyQt5.QtWidgets
>
> ...a path issue?

If you installed "python3-pyqt5", you probably want to run "python3
tut8.py". There are potentially two completely separate Python
interpreters installed - version 2.7, and the latest available version
3.x (probably 3.4 or 3.5). You've installed a package for Python 3,
but haven't installed the corresponding Python 2 package, so it won't
run under the Python 2 interpreter. Compare these:

$ python --version
$ python3 --version

I suspect that "python3 tut8.py" should work. If it doesn't, post some
more info about your Idle installation; it might give a hint as to
what's going on.

ChrisA


From adiamond1978 at gmail.com  Sun Nov  8 11:27:16 2015
From: adiamond1978 at gmail.com (Andrew Diamond)
Date: Sun, 8 Nov 2015 08:27:16 -0800 (PST)
Subject: [Ubuntu] PyQt5
In-Reply-To: <mailman.139.1446999736.16136.python-list@python.org>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
 <mailman.139.1446999736.16136.python-list@python.org>
Message-ID: <5c057628-f45a-4734-bdda-8472c9ad9632@googlegroups.com>

On Sunday, November 8, 2015 at 11:22:30 AM UTC-5, Chris Angelico wrote:
> On Mon, Nov 9, 2015 at 3:03 AM, Andrew Diamond <adiamond1978 at gmail.com> wrote:
> > On Saturday, November 7, 2015 at 10:13:25 PM UTC-5, Andrew Diamond wrote:
> >> Hi!
> >>
> >> I'm fairly new to Python, and installed pyqt5 and began working through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/  However, whenever I click one of the buttons or menus in the example apps I run that is supposed to quit the application, it locks up.  This happens with all the examples I installed that handle code to quit the app.
> >>
> >> Running Ubuntu 15.10, and installed pyqt5 via:
> >>
> >> sudo apt-get install python3-pyqt5
> >> sudo apt-get install qtcreator
> >>
> >> Thank you in advance for any assistance!
> >
> > I just read somewhere that the issue could be because I was trying to run these examples from within Idle.  However, when I try to run them from the terminal, I run into another snag:
> >
> > andrew at andrew-Satellite-P755:~/Programming/Python$ python tut8.py
> > Traceback (most recent call last):
> >   File "tut8.py", line 16, in <module>
> >     from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication
> > ImportError: No module named PyQt5.QtWidgets
> >
> > ...a path issue?
> 
> If you installed "python3-pyqt5", you probably want to run "python3
> tut8.py". There are potentially two completely separate Python
> interpreters installed - version 2.7, and the latest available version
> 3.x (probably 3.4 or 3.5). You've installed a package for Python 3,
> but haven't installed the corresponding Python 2 package, so it won't
> run under the Python 2 interpreter. Compare these:
> 
> $ python --version
> $ python3 --version
> 
> I suspect that "python3 tut8.py" should work. If it doesn't, post some
> more info about your Idle installation; it might give a hint as to
> what's going on.
> 
> ChrisA

You were absolutely correct!

$ python3 tut8.py 

...worked great, thanks!!


From lac at openend.se  Sun Nov  8 11:57:04 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 08 Nov 2015 17:57:04 +0100
Subject: =?US-ASCII?Q?how_to_copy_PyObject_*_memory_d?=
 =?US-ASCII?Q?ata_to_another_memory_address=3F=0A=0A?=
In-Reply-To: <1446902615952.dslp41enande24vd1gfb0x4r@android.mail.163.com>
References: <1446902615952.dslp41enande24vd1gfb0x4r@android.mail.163.com>
Message-ID: <201511081657.tA8Gv4dL028917@fido.openend.se>

In a message of Sat, 07 Nov 2015 21:23:51 +0800, yueyoum writes:
>I'm working on a C program that has Python embedded. The host program is multi processes, which communicate via shared memory (mmap). I create a Python object (e.g., PyDict_New) in one process. How can I copy this data to shared memory so that the other process can obtain this data and convert to Python Object? ????????
>-- 
>https://mail.python.org/mailman/listinfo/python-list

It is not clear that what you want to do can be done in the general
sense.  See Alex Martelli's explanation here:
tackoverflow.com/questions/1268252/python-possible-to-share-in-memory-data-between-2-separate-processes/1269055#1269055

Any chance that instead of trying to share a PyDict you could share an
array?  If so, multiprocessing will work for you.

Or the last reference there is to some lower level inter process communication
things you can use in Python.  I have never tried them, so have no idea
how well written the code is.

Laura


From torriem at gmail.com  Sun Nov  8 12:04:06 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sun, 08 Nov 2015 10:04:06 -0700
Subject: Puzzled
In-Reply-To: <4CFEDC132D44AC49BA0E91FBEB947119084AAD2A1E@DCBL123VX.root.sutterhealth.org>
References: <4CFEDC132D44AC49BA0E91FBEB947119084A742852@DCBL123VX.root.sutterhealth.org>
 <201511011020.tA1AKYAM004182@fido.openend.se>
 <4CFEDC132D44AC49BA0E91FBEB947119084A8D5E6C@DCBL123VX.root.sutterhealth.org>
 <563CADCD.8070307@gonnerman.org>
 <4CFEDC132D44AC49BA0E91FBEB947119084AAD2A1E@DCBL123VX.root.sutterhealth.org>
Message-ID: <563F8086.7010302@gmail.com>

On 11/06/2015 02:36 PM, Robinson, Wendy wrote:
> Ah, ok.... I get it now.
> Thanks both!

Glad you got it!  Thanks for letting us know, too.


From bc at freeuk.com  Sun Nov  8 12:54:57 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 17:54:57 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.135.1446998410.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
Message-ID: <n1o25a$3s3$1@dont-email.me>

On 08/11/2015 15:59, Michael Torrie wrote:
> On 11/08/2015 04:19 AM, BartC wrote:
>
>>> That elegant dynamism comes at a cost: method lookup is not a constant
>>> memory offset. Rather, it is a dictionary lookup.
>>
>> I've never understood why this seems to be necessary in Python. Why do
>> names have to be looked up? (I'm assuming this is searching by name in
>> some sort of table.)
>>
>> When a module is compiled, while the compiler can't see the definitions
>> inside the imported modules, it /will/ know all the names that appear in
>> this module, so it can organise them into fixed tables. Then the names
>> can be referred to by index. (I think LOAD_FAST does this.)
>>
>> Or is eval() the culprit here by making most optimisations impossible?
>
> Perhaps I'm misunderstanding what you're saying, here, but the reason a
> lookup has to be performed is because python variables are not like C
> variables. They aren't boxes per se.  They are names bound to objects.
> so doing something like
>
> a += 1
>
> Actually assigns the name "a" to an entirely new object than the one it
> had before, which, from the interpreters point of view, is in an
> entirely different memory location.

That would be true for locals as well. But as far as I can tell from the 
CPython source code, byte-codes uses an index to represent a local, 
which represents an entry into a linear table.

I can't quite see why that can't be done for global names and for 
attributes too (ie. the names that follow a ".").

Attributes are a more difficult because there can be multiple instances 
of each name, and Python won't know which one is meant, so it needs to 
be resolved at each use.

So in the case of A.B(), Python apparently looks up "B" in the names 
associated with object A (and also, someone said, with the class of 
which A is an instance if the first lookup fails).

I had in mind a different approach, where a table exists for each 
different attribute, which contains an entry for each owner class. 
Usually this table will be small, or will have just one entry, so is 
quick to search.

However, another feature of Python makes that impractical: the ability 
of any instance of a class to have arbitrary sets of attributes. There 
could be millions of such instances, all named "B".

Now, if methods could only be part of a class definition, then with 
A.B() rather than A.B, there will be a limited number of classes that 
could have a method "B", so the short table idea could work.

But then, A.B could be assigned the name of a function, which is then 
called using A.B(), the same as method-calling syntax!

So it looks like Python is stuck with its name lookups.

-- 
Bartc


From rosuav at gmail.com  Sun Nov  8 13:01:21 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 05:01:21 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n1o25a$3s3$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
Message-ID: <CAPTjJmq+-wr3j5d6BpCxBijLZ6cEfk9mCA=2cz7TNg4JT5s90Q@mail.gmail.com>

On Mon, Nov 9, 2015 at 4:54 AM, BartC <bc at freeuk.com> wrote:
> That would be true for locals as well. But as far as I can tell from the
> CPython source code, byte-codes uses an index to represent a local, which
> represents an entry into a linear table.
>
> I can't quite see why that can't be done for global names and for attributes
> too (ie. the names that follow a ".").

At compilation time, the set of local names is locked in permanently.
That's not true of any other namespace (except nonlocals, which are
still locals, just not yours). Attributes and global names (which are
attributes of the current module) can be added and removed
dynamically, so they can't be assigned to slots; attributes can even
be simulated via __getattr__ and __getattribute__.

ChrisA


From no.email at nospam.invalid  Sun Nov  8 13:28:24 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Sun, 08 Nov 2015 10:28:24 -0800
Subject: [ANN] MicroPython 1.5
References: <mailman.132.1446996971.16136.python-list@python.org>
Message-ID: <87ziyotkfr.fsf@nightsong.com>

Paul Sokolovsky <pmiscml at gmail.com> writes:
> Recent 1.5 release is an important milestone for the project, major
> changes including:

Thanks for posting this.  We don't hear enough about MicroPython on
this newsgroup so it's good to get these announcements.

Is the language still Python 3.4?  Will it implement 3.5 sometime soon?

> 1. Advanced REPL support with smart auto-indent and auto-completion

Hmm does this make the code footprint significantly bigger?

> 2. Support for client SSL connections.

Nice.  Does it check the server certificate?  Is it based on TLSLite by
any chance?

> 5. There're now 2 well-supported microcontroller boards for
> MicroPython, and dozen(s) community-supported ones.

The PyBoard is very nice, but what is the other one?  I don't see
anything about it on the MicroPython web site.  (Hmm, maybe you mean the
Micro Bit).

Btw, I notice that the "store" page doesn't show any products under my
normal adblock settings.  It's probably best to make it a normal page
instead of an AJAX one.

> MicroPython supports growing subset of Python3 standard library
> (including simplified asyncio package)

This would look much nicer with the new Python 3.5 syntax.


From bc at freeuk.com  Sun Nov  8 13:58:36 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 18:58:36 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.142.1447005691.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
Message-ID: <n1o5sl$joc$1@dont-email.me>

On 08/11/2015 18:01, Chris Angelico wrote:
> On Mon, Nov 9, 2015 at 4:54 AM, BartC <bc at freeuk.com> wrote:
>> That would be true for locals as well. But as far as I can tell from the
>> CPython source code, byte-codes uses an index to represent a local, which
>> represents an entry into a linear table.
>>
>> I can't quite see why that can't be done for global names and for attributes
>> too (ie. the names that follow a ".").
>
> At compilation time, the set of local names is locked in permanently.
> That's not true of any other namespace (except nonlocals, which are
> still locals, just not yours). Attributes and global names (which are
> attributes of the current module) can be added and removed
> dynamically, so they can't be assigned to slots; attributes can even
> be simulated via __getattr__ and __getattribute__.

Yes, that's yet another way that the language design makes things 
difficult (for those who want to streamline its implementation).

For most purposes, the set of attribute names that can follow a dot are 
limited and fixed, by the occurrences of such names in a source file. So 
they can be assigned a slot.

But then, you say that additional attributes, potentially millions of 
different ones, can be invented at runtime. Although I don't see how it 
can remove names that are part of the source code: if "A.B" is in the 
file, then surely "A" and "B" always have to be present in some table or 
other.

-- 
Bartc


From paul.hermeneutic at gmail.com  Sun Nov  8 14:08:20 2015
From: paul.hermeneutic at gmail.com (paul.hermeneutic at gmail.com)
Date: Sun, 8 Nov 2015 12:08:20 -0700
Subject: [ANN] MicroPython 1.5
In-Reply-To: <87ziyotkfr.fsf@nightsong.com>
References: <mailman.132.1446996971.16136.python-list@python.org>
 <87ziyotkfr.fsf@nightsong.com>
Message-ID: <CAJ4+4aoNUBS8cXSYsxyACekyU4bs7h5j5kPDpoq5ycmry5p0yQ@mail.gmail.com>

What is the possibility that MicroPython could be another build from the
base python.org sources? Python already gets built for a variety of
architectures. Could a MicroPython be another one? In that way, it would
always be up to date on language changes.

On Sun, Nov 8, 2015 at 11:28 AM, Paul Rubin <no.email at nospam.invalid> wrote:

> Paul Sokolovsky <pmiscml at gmail.com> writes:
> > Recent 1.5 release is an important milestone for the project, major
> > changes including:
>
> Thanks for posting this.  We don't hear enough about MicroPython on
> this newsgroup so it's good to get these announcements.
>
> Is the language still Python 3.4?  Will it implement 3.5 sometime soon?
>
> > 1. Advanced REPL support with smart auto-indent and auto-completion
>
> Hmm does this make the code footprint significantly bigger?
>
> > 2. Support for client SSL connections.
>
> Nice.  Does it check the server certificate?  Is it based on TLSLite by
> any chance?
>
> > 5. There're now 2 well-supported microcontroller boards for
> > MicroPython, and dozen(s) community-supported ones.
>
> The PyBoard is very nice, but what is the other one?  I don't see
> anything about it on the MicroPython web site.  (Hmm, maybe you mean the
> Micro Bit).
>
> Btw, I notice that the "store" page doesn't show any products under my
> normal adblock settings.  It's probably best to make it a normal page
> instead of an AJAX one.
>
> > MicroPython supports growing subset of Python3 standard library
> > (including simplified asyncio package)
>
> This would look much nicer with the new Python 3.5 syntax.
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From ian.g.kelly at gmail.com  Sun Nov  8 14:51:03 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sun, 8 Nov 2015 12:51:03 -0700
Subject: Question about math.pi is mutable
In-Reply-To: <n1o5sl$joc$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
Message-ID: <CALwzidk6Cd9433JJT6unDDwjY92z9GUWoq+zXWJUQkBmWNsANw@mail.gmail.com>

On Nov 8, 2015 12:01 PM, "BartC" <bc at freeuk.com> wrote:
>
> But then, you say that additional attributes, potentially millions of
different ones, can be invented at runtime. Although I don't see how it can
remove names that are part of the source code: if "A.B" is in the file,
then surely "A" and "B" always have to be present in some table or other.

Gratuitous example:

def factory(name):
    class inner:
        # stuff
    inner.__name__ = name
    return inner

One = factory('One')
Two = factory('Two')

# factory is no longer needed, so remove it from globals.
del factory


From pmiscml at gmail.com  Sun Nov  8 15:27:58 2015
From: pmiscml at gmail.com (Paul Sokolovsky)
Date: Sun, 8 Nov 2015 22:27:58 +0200
Subject: [ANN] MicroPython 1.5
In-Reply-To: <87ziyotkfr.fsf@nightsong.com>
References: <mailman.132.1446996971.16136.python-list@python.org>
 <87ziyotkfr.fsf@nightsong.com>
Message-ID: <20151108222758.67e86320@x230>

Hello,

On Sun, 08 Nov 2015 10:28:24 -0800
Paul Rubin <no.email at nospam.invalid> wrote:

> Paul Sokolovsky <pmiscml at gmail.com> writes:
> > Recent 1.5 release is an important milestone for the project, major
> > changes including:
> 
> Thanks for posting this.  We don't hear enough about MicroPython on
> this newsgroup so it's good to get these announcements.
> 
> Is the language still Python 3.4?  Will it implement 3.5 sometime
> soon?

Yes, we already implement the most important 3.5 feature - ability to
format bytes: b"foo%s" % b"bar" ;-).

> > 1. Advanced REPL support with smart auto-indent and auto-completion
> 
> Hmm does this make the code footprint significantly bigger?

No, as everything else in MicroPython, code implementing this feature
is well-optimized, it did cost few hundreds of bytes to implement.

> > 2. Support for client SSL connections.
> 
> Nice.  Does it check the server certificate?  

The driving force for adding SSL was being able to download package
from PyPI (for builtin upip package manager). Unfortunately, PyPI forces
SSL, so previously we had to fallback to wget for downloads, which
limited upip to unix-like systems. So, the way we use SSL is as bloated
plain HTTP, just to workaround PyPI's maintainers' decision to raise
the bar too high to access it. Consequently, nobody yet worked on
certificate checking and other stuff.

> Is it based on TLSLite by any chance?

I had an idea to port TLSLite and even submitted couple of patches to
it, I had an idea to write a module titled "insecureSSL" which would
just emulate SSL by doing as little as possible processing and using
static session keys, etc. - just to prove the point that there can't be
security without both parties consenting, and mis-applied "security" is
nothing but a denial-of-service. But I gave up in the end, deciding to
take that productively and add generic SSL client support using axTLS
library (which was also optimized to meet MicroPython code size
standards).

(You see, these questions touched ranty feelings - thanks for
asking ;-) ).

> > 5. There're now 2 well-supported microcontroller boards for
> > MicroPython, and dozen(s) community-supported ones.
> 
> The PyBoard is very nice, but what is the other one?  I don't see
> anything about it on the MicroPython web site.  (Hmm, maybe you mean
> the Micro Bit).

It's WiPy, http://wipy.io/ , WiFi-enabled board which had successful
kickstarter in the spring and last month shipped ready boards. Micro
Bit would take some time before general availability of course.

> Btw, I notice that the "store" page doesn't show any products under my
> normal adblock settings.  It's probably best to make it a normal page
> instead of an AJAX one.
> 
> > MicroPython supports growing subset of Python3 standard library
> > (including simplified asyncio package)
> 
> This would look much nicer with the new Python 3.5 syntax.

There was initial patch to add initial async/await support a week within
corresponding PEP was initially posted. But we decided not to haste with
it, or we can add feature which nobody really uses (while we have bunch
of features which almost everyone would use, but which aren't yet
there). So, we decided yo do our homework, and let asyncio/async-await
people do theirs on popularizing it (every 10th Python programmer
using it seems like good target, now it's probably every 10,000th if not
100,000th).


Thanks for the feedback!

-- 
Best regards,
 Paul                          mailto:pmiscml at gmail.com


From pmiscml at gmail.com  Sun Nov  8 15:53:33 2015
From: pmiscml at gmail.com (Paul Sokolovsky)
Date: Sun, 8 Nov 2015 22:53:33 +0200
Subject: [ANN] MicroPython 1.5
In-Reply-To: <CAJ4+4aoNUBS8cXSYsxyACekyU4bs7h5j5kPDpoq5ycmry5p0yQ@mail.gmail.com>
References: <mailman.132.1446996971.16136.python-list@python.org>
 <87ziyotkfr.fsf@nightsong.com>
 <CAJ4+4aoNUBS8cXSYsxyACekyU4bs7h5j5kPDpoq5ycmry5p0yQ@mail.gmail.com>
Message-ID: <20151108225333.776b9ee0@x230>

Hello,

On Sun, 8 Nov 2015 12:08:20 -0700
paul.hermeneutic at gmail.com wrote:

> What is the possibility that MicroPython could be another build from
> the base python.org sources? Python already gets built for a variety
> of architectures. Could a MicroPython be another one? In that way, it
> would always be up to date on language changes.

There's zero possibility for this - MicroPython is from-scratch
implementation carefully optimized for code size and memory usage,
that's how it's up to 50 times smaller than CPython and can run with
~1000 times less RAM than CPython usually runs with.

Support for the latest features is not the aim of MicroPython, instead
it's being able to use the same great language on systems where CPython
simply could never run. That necessitates being on a diet and leaving
out not just the latest lesser-known features, but even quite a few of
old more widely known ones.

That said, the core of the language is there and any Python programmer
should feel straight at home. And it's Python*3*, so it's pretty fresh
anyway, knowing that half of our community still sits on Python2 and
never tried Python3. (Hacking on MicroPython is how I get to use
Python3 myself, on my dayjob we still use Python2).

[]

-- 
Best regards,
 Paul                          mailto:pmiscml at gmail.com


From ben+python at benfinney.id.au  Sun Nov  8 16:00:34 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 08:00:34 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
Message-ID: <85lha8i4ul.fsf@benfinney.id.au>

BartC <bc at freeuk.com> writes:

> I've never understood why this seems to be necessary in Python. Why do
> names have to be looked up? (I'm assuming this is searching by name in
> some sort of table.)

No, it is literally looking the name up as a key in a namespace
dictionary ? which is just like any other Python dictionary, but
nominated internally for use as the namespace dictionary.

The distinction is important, because like any other dictionary it can
change at run-time and the bindings between name and value can change,
can be added, and can be removed.

> When a module is compiled, while the compiler can't see the
> definitions inside the imported modules, it /will/ know all the names
> that appear in this module, so it can organise them into fixed tables.

Not true. The namespace can change dynamically, which is another way of
what people have been trying to tell you all through this thread.

The compiler *cannot* know what the names will be at every single point
they'll be looked un in the namespace dictionary. This dynamism of each
namespace is a Python feature.

-- 
 \                  ?It is ? incumbent upon us to recognize that it is |
  `\    inappropriate for religion to play any role in issues of state |
_o__)        [of] a modern democracy.? ?Lawrence M. Krauss, 2012-05-28 |
Ben Finney



From kent at z-sverige.nu  Sun Nov  8 16:27:06 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Sun, 8 Nov 2015 16:27:06 -0500
Subject: using binary in python
Message-ID: <20151108212706.GA29701@z-sverige.nu>

Hi there,
Lets say I want to play around with binary files in python.
Opening and using files in python is something that I think I've sort of got the hang of.
The thing im wondering about is binary files.
While searching for binary and python I started reading about bin().
I can use bin() to convert integers to binary. 
Now, I thought..  some way it should be possible to write "binary" files.
That is, non ascii-files.  For example, on Linux, if I run the command 'less' on a binary;
for example /bin/ls, then the command asks me if I really want to do it, since its a binary file.
I know why, since the non ascii-stuff messes up the terminal, and most likely since you rarely want to
look at a binary file with less. 
Well, lets assume I want to write and read binary.  How is it done?
The built in bin() function only converts integers to binary but the variable or return is still just letters right?
Converting the integer '1' to binary with bin() return 0b1. Which is ok. Its the binary representation of integer 1. 
But since.. there is files which contains data that is not representable as ascii, then I assume it can be written.
But can it by Python?

Ok, I get the feeling now that its hard to understand my question. I assume in the C language its just matter of 
writing a complex struct with strange variables and just write it to a file. But in python..?

Can some one give a short explenation of a python write to file, that makes it a binary file?

Thanks alot,  and forgive me for my stupid questions. :)
/Kent Nyberg


From rosuav at gmail.com  Sun Nov  8 16:47:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 08:47:38 +1100
Subject: [ANN] MicroPython 1.5
In-Reply-To: <20151108225333.776b9ee0@x230>
References: <mailman.132.1446996971.16136.python-list@python.org>
 <87ziyotkfr.fsf@nightsong.com>
 <CAJ4+4aoNUBS8cXSYsxyACekyU4bs7h5j5kPDpoq5ycmry5p0yQ@mail.gmail.com>
 <20151108225333.776b9ee0@x230>
Message-ID: <CAPTjJmp5yLChFok8e7_ghjFNDiew5jAwyZVj_r_2XgcoHgX7Ug@mail.gmail.com>

On Mon, Nov 9, 2015 at 7:53 AM, Paul Sokolovsky <pmiscml at gmail.com> wrote:
> On Sun, 8 Nov 2015 12:08:20 -0700
> paul.hermeneutic at gmail.com wrote:
>
>> What is the possibility that MicroPython could be another build from
>> the base python.org sources? Python already gets built for a variety
>> of architectures. Could a MicroPython be another one? In that way, it
>> would always be up to date on language changes.
>
> There's zero possibility for this - MicroPython is from-scratch
> implementation carefully optimized for code size and memory usage,
> that's how it's up to 50 times smaller than CPython and can run with
> ~1000 times less RAM than CPython usually runs with.

Putting this another way: MicroPython is a *different implementation*
of Python, which just happens to be in the same language as CPython. A
number of Python implementations are listed here:

https://wiki.python.org/moin/PythonImplementations

Each one is a distinct implementation of (some version of) the same
language spec called "Python", which is different from a build target
of CPython. For example, there are several implementations designed to
run inside a web browser, and while it's theoretically possible to
port some other Python implementation to JavaScript (which is what
PyPyJS did with PyPy), it's usually easier to instead implement
something specifically in/for JS (eg Brython). There's no way to say
"CPython, go build yourself for the platform known as Mozilla
Firefox", because that would be hopelessly inefficient.

ChrisA


From andre.roberge at gmail.com  Sun Nov  8 17:02:39 2015
From: andre.roberge at gmail.com (=?ISO-8859-1?Q?Andr=E9_Roberge?=)
Date: Sun, 8 Nov 2015 14:02:39 -0800 (PST)
Subject: python PEP suggestion
In-Reply-To: <mailman.130.1446996920.16136.python-list@python.org>
References: <mailman.130.1446996920.16136.python-list@python.org>
Message-ID: <c2846659-1a1a-4cb6-a95e-ac654492fb4e@googlegroups.com>

On Sunday, 8 November 2015 11:35:32 UTC-4, Dan Strohl  wrote:
> All,
> 
> I wanted to run the following thought past the list as a possible PEP enhancement suggestion to see if it feels like something that is worth proposing.   I know it is not in the PEP format at this point, I can, and will, clean it up if needed, I am just trying to throw it against the wall at this point to see if it resonates... (or if it falls flat and goes "splat" <grin>).
> 
> Thoughts?
> 
> Dan Strohl
>
Snip

You might want to post this to the python-ideas list.

Andr?


From tjreedy at udel.edu  Sun Nov  8 17:26:36 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 8 Nov 2015 17:26:36 -0500
Subject: python PEP suggestion
In-Reply-To: <cf746bff3459405cbdf04acabce99cae@seaexchmbx03.olympus.F5Net.com>
References: <cf746bff3459405cbdf04acabce99cae@seaexchmbx03.olympus.F5Net.com>
Message-ID: <n1oi72$d2h$1@ger.gmane.org>

On 11/6/2015 1:21 PM, Dan Strohl wrote:
> All,
>
> I wanted to run the following thought past the list as a possible PEP enhancement suggestion to see if it feels like something that is worth proposing.   I know it is not in the PEP format at this point, I can, and will, clean it up if needed, I am just trying to throw it against the wall at this point to see if it resonates... (or if it falls flat and goes "splat" <grin>).
>
> Thoughts?

At first glance, plausible, but I am not sure needed, and it seems a bit 
contrary to how Python currently works.

> New special method name to allow for more flexible object type casting/access, and extend type() to cast objects using this special method name.
>
> Overview:
>
> Have a new special method name that would allow a given objects to request information from another object in a given type, or to cast an object into a different type, and extend the built in type() function to use this.
>
> Rationale:
> There is currently __str__, __int__, and __bool__ that allow me to tell an object how it should reply to a request for these types of basic data types.  However if I want to access a copy of the objet in dict form, or as a list, or if I am trying to convert something using json, there is no standard way of doing that for a custom object (I know I can do __getitem__ and/or __iter__, but I many processes don't try these if the object is not a subclass of dict or list/tuple)

Conditional execution, indexing (__index__), numeric conversions 
(__float__ also), and displaying are special cases related to syntax 
operations.  Functions that unnecessarily restrict inputs to subclasses 
of list or dict will not be solved by this.  You have left out the use 
of abstract base classes.  An iterable that can be used as a mapping can 
register itself as a mapping.  Json could check whether something is a 
sequence or mapping and iterate to get values or pairs of values.  Of 
course, the tranformation would be unidirectional.

> Proposal:
> What I am proposing is something like:
>
> object.__cast__(self, to_class):
>                                """
>                                to_class: the class type that you wish to return.
>                                """

The excessive indents of 31 and 15 spaces make the rest of this post 
unnecessarily hard to read.

-- 
Terry Jan Reedy



From bc at freeuk.com  Sun Nov  8 17:35:06 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 22:35:06 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.147.1447016469.16136.python-list@python.org>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.147.1447016469.16136.python-list@python.org>
Message-ID: <n1oiik$90r$1@dont-email.me>

On 08/11/2015 21:00, Ben Finney wrote:
> BartC <bc at freeuk.com> writes:
>
>> I've never understood why this seems to be necessary in Python. Why do
>> names have to be looked up? (I'm assuming this is searching by name in
>> some sort of table.)
>
> No, it is literally looking the name up as a key in a namespace
> dictionary ? which is just like any other Python dictionary, but
> nominated internally for use as the namespace dictionary.
>
> The distinction is important, because like any other dictionary it can
> change at run-time and the bindings between name and value can change,
> can be added, and can be removed.

That part is not a problem.

>> When a module is compiled, while the compiler can't see the
>> definitions inside the imported modules, it /will/ know all the names
>> that appear in this module, so it can organise them into fixed tables.
>
> Not true. The namespace can change dynamically, which is another way of
> what people have been trying to tell you all through this thread.
>
> The compiler *cannot* know what the names will be at every single point
> they'll be looked un in the namespace dictionary. This dynamism of each
> namespace is a Python feature.

Suppose this is the python program:

import m
a=10
b=20
c=30
m.f()

The set of global names the compiler knows will be ("m","a","b","c").

I don't believe code can remove these names (that would cause problems). 
You say the set of global names can be added to - after this lot, but I 
can't see that the first four are going to change.

Therefore these names could be referred to by index.

Attributes are harder because they are more of a free-for-all, but 
suppose you do have m.f().

"m" is easy, it's entry 0 in the global table for this module, so no 
lookup-by-name is needed. You examine it, and it's a module.

It's now necessary to find f within the global table for m. This is 
where it gets tricky if you want to avoid a lookup. And I expect you 
will say that any code can randomly add names within the global table of m.

But bear with me. Suppose the interpreter were to maintain a table for 
each static (not runtime) attribute encountered in the source code. The 
compile can produce empty tables for the attributes it's seen. In this 
case the table for "f" would be empty: (). The compiler will also 
produce a list of such tables for all attributes.

Here there is only one, and the "f" table will have index 0, which is 
what can be used within the byte-code.

The hard part would be in building and maintaining that table. When 
module m is loaded, let's say it defines function "f". Now that can be 
used to create the first entry in the attribute table for "f": ($m, 
$m.f). Here, $m is some internal reference to m, and $m.f is some 
internal reference to m.f().

Now back to resolving m.f(): we know the "m" part is module $m. For "f", 
it looks through its attribute table (remember it's index 0, so instant 
access), and there is only one entry. We're lucky as that entry's owner 
matches the "m." part of this access. So we know it refers to $m.f. No 
lookups by name needed in this case.

However not all random attributes will be neatly defined somewhere as 
functions or classes that will be listed in these little tables. So 
sometimes, an actual lookup will still be needed.

-- 
Bart C


From ben+python at benfinney.id.au  Sun Nov  8 17:54:20 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 09:54:20 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.147.1447016469.16136.python-list@python.org>
 <n1oiik$90r$1@dont-email.me>
Message-ID: <857flshzkz.fsf@benfinney.id.au>

BartC <bc at freeuk.com> writes:

> On 08/11/2015 21:00, Ben Finney wrote:
> > The namespace can change dynamically, which is another way of what
> > people have been trying to tell you all through this thread.
> >
> > The compiler *cannot* know what the names will be at every single
> > point they'll be looked un in the namespace dictionary. This
> > dynamism of each namespace is a Python feature.
>
> Suppose this is the python program:
>
> import m
> a=10
> b=20
> c=30
> m.f()
>
> The set of global names the compiler knows will be ("m","a","b","c").
>
> I don't believe code can remove these names (that would cause
> problems).

It may indeed cause problems. Those names can nevertheless be changed.

Names at module level are simply attributes on the module object. The
module can gain attributes, lose attributes, and its attributes can
chage; its namespace is just as mutable as any other object's namespace.

> You say the set of global names can be added to - after this lot, but
> I can't see that the first four are going to change.

You have not yet learned enough about the Python data model:

    A module object has a namespace implemented by a dictionary object
    (this is the dictionary referenced by the __globals__ attribute of
    functions defined in the module). Attribute references are
    translated to lookups in this dictionary, e.g., m.x is equivalent
    to m.__dict__["x"]. A module object does not contain the code
    object used to initialize the module (since it isn?t needed once
    the initialization is done).

    <URL:https://docs.python.org/3/reference/datamodel.html>

Any name can be deleted, just like any other reference, with the ?del?
statement.

Any reference (including names) can be added or changed in a module
namespace like any other object's namespace.

> Attributes are harder because they are more of a free-for-all

Please understand that a module *is* an object, and a name in a module's
namespace *is* an attribute on that module.

Also, please *learn about* the way Python works; you have certainly been
here long enough to know how to look up answers in the documentation
instead of making ignorant assertions here.

-- 
 \       ?What I resent is that the range of your vision should be the |
  `\                                 limit of my action.? ?Henry James |
_o__)                                                                  |
Ben Finney



From tjreedy at udel.edu  Sun Nov  8 18:05:32 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sun, 8 Nov 2015 18:05:32 -0500
Subject: [Ubuntu] PyQt5
In-Reply-To: <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
Message-ID: <n1okg2$da7$1@ger.gmane.org>

On 11/8/2015 11:03 AM, Andrew Diamond wrote:
> On Saturday, November 7, 2015 at 10:13:25 PM UTC-5, Andrew Diamond
> wrote:
>> Hi!
>>
>> I'm fairly new to Python, and installed pyqt5 and began working
>> through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/
>> However, whenever I click one of the buttons or menus in the
>> example apps I run that is supposed to quit the application, it
>> locks up.

What is 'it'?  And what does 'lock up' mean?  Did the gui freeze and not 
disappear?  Or did IDLE itself freeze, and even the menu quit working?

>> This happens with all the examples I installed that
>> handle code to quit the app.
>>
>> Running Ubuntu 15.10, and installed pyqt5 via:
>>
>> sudo apt-get install python3-pyqt5 sudo apt-get install qtcreator

> I just read somewhere that the issue could be because I was trying to
> run these examples from within Idle.

I am an IDLE maintainer.  Am I to take it that everything ran fine 
before you tried to quit?  If not, I would want to know why and try to fix.

If you run tut.py from an IDLE editor, IDLE tries to run it the same as 
if you ran it at a console in the tut.py directory with 'python3 -i 
tut.py'.  I can imagine that there might be a problem with the 
transition from gui mode to interactive shell mode, though it works for 
tkinter apps.  You said 'python3 tut.py' works.  What happens if you add 
the '-i' option?  I'd like to know if the transition problem is in 
(Py)qt5 or in IDLE's simulation of '-i'.

-- 
Terry Jan Reedy



From bc at freeuk.com  Sun Nov  8 18:54:15 2015
From: bc at freeuk.com (BartC)
Date: Sun, 8 Nov 2015 23:54:15 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.152.1447024427.16136.python-list@python.org>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
Message-ID: <n1on71$san$1@dont-email.me>

On 08/11/2015 23:13, Dennis Lee Bieber wrote:
> On Sun, 8 Nov 2015 18:58:36 +0000, BartC <bc at freeuk.com> declaimed the
> following:
>
>> But then, you say that additional attributes, potentially millions of
>> different ones, can be invented at runtime. Although I don't see how it
>> can remove names that are part of the source code: if "A.B" is in the
>> file, then surely "A" and "B" always have to be present in some table or
>> other.
>
> -=-=-=-=- module.py
>
> class Something(object):
> 	def __init__(self):
> 		pass
>
> -=-=-=-=- main.py
>
> import module
>
> module.remote = module.Something()
> nonremote = module.remote
> nonremote.x = "Looky here"
> print module.remote.x
> module.remote.x = 3.14
> print nonremote.x
> module.remote = None
> print nonremote.x
> print module.remote.x

Is this typical Python code? Creating global objects in other modules 
(or writing all over essential data structures in a library module).

If most code is going to be more sensible, then I mentioned an approach 
in my other post just over an hour ago. The idea there was to optimise 
attribute lookups when code is written with more restraint. (So defining 
functions, classes and attributes within classes in a boring manner.)

> 	Where do you propose to "tableize" remote, nonremote, and x. "remote"
> doesn't exist inside module.py until one executes main.py -- so it can't be

In your example, only attributes "remote" and "x" exist. But the tables 
for those will be empty as it is not practical to add in runtime-created 
attributes. Then, a conventional lookup would be needed.

> optimized to when the compiler parses module.py (creating, in most cases a
> bytecode module.pyc). You can't optimize it to main.py since (not shown in
> my example) there may be another imported package that also imports module
> and references module.remote -- and could even replace it with a new object
> (in which case nonremote is still associated with the old object, not the
> new one)

The tables would reflect the static layout of the attributes as defined 
in the source code. Since the source code is finite, the tables will be 
also (unlike runtime when a billion attributes could be created).

If your module.py code is tweaked like this:

  class Something(object):
         x=0
  	def __init__(self):
  		pass

  remote=0

Then 'x' and 'remote' become static attributes that can now added to 
tables for fast lookup. Although this does require that these two are 
effectively 'declared'.

-- 
Bartc


From ben+python at benfinney.id.au  Sun Nov  8 19:00:08 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 11:00:08 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me>
Message-ID: <8537wghwjb.fsf@benfinney.id.au>

BartC <bc at freeuk.com> writes:

> Is this typical Python code? Creating global objects in other modules
> (or writing all over essential data structures in a library module).

Not ?creating global objects?, but changing the referent of a name in
some other module. Yes, that's quite a common technique. Does that
surprise you?

If it surprises you, hopefully you can learn some more Python with this
new knowledge.

-- 
 \             ?We can't depend for the long run on distinguishing one |
  `\         bitstream from another in order to figure out which rules |
_o__)               apply.? ?Eben Moglen, _Anarchism Triumphant_, 1999 |
Ben Finney



From rosuav at gmail.com  Sun Nov  8 19:04:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 11:04:26 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <8537wghwjb.fsf@benfinney.id.au>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
Message-ID: <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:00 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> BartC <bc at freeuk.com> writes:
>
>> Is this typical Python code? Creating global objects in other modules
>> (or writing all over essential data structures in a library module).
>
> Not ?creating global objects?, but changing the referent of a name in
> some other module. Yes, that's quite a common technique. Does that
> surprise you?

Changing the referent of an existing name, definitely. Creating new
names, not so much. You don't often reach into another module and
create a new attribute.

Testing/mocking is a completely separate consideration (eg you can
inject a shadow for a built-in name); if some Python implementation
has a fast path that gets defeated by "module.int = MagicInt", and it
causes the tests to run slower, so be it. Other than that, I can't
think of many cases (actually, can't think of any, off hand) where you
inject names into other modules.

ChrisA


From bc at freeuk.com  Sun Nov  8 19:11:58 2015
From: bc at freeuk.com (BartC)
Date: Mon, 9 Nov 2015 00:11:58 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.153.1447027222.16136.python-list@python.org>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me>
 <mailman.153.1447027222.16136.python-list@python.org>
Message-ID: <n1oo88$vj1$1@dont-email.me>

On 09/11/2015 00:00, Ben Finney wrote:
> BartC <bc at freeuk.com> writes:
>
>> Is this typical Python code? Creating global objects in other modules
>> (or writing all over essential data structures in a library module).
>
> Not ?creating global objects?, but changing the referent of a name in
> some other module. Yes, that's quite a common technique. Does that
> surprise you?

Changing the referent (I assume that just means assigning to it or 
updating the associated value) wouldn't be a problem. Provided the name 
was defined in that other module, because then it is a name the compiler 
would know about.

(And, more importantly, someone reading the code in that module would 
know about.)

> If it surprises you, hopefully you can learn some more Python with this
> new knowledge.

Yes, that it's more of a crazy language than it looks at first; I can 
write a simple module like this:

pass

which looks like an empty module, yet for all I know will end up contain 
hundreds of variables by the time it's run.

(I normally use my own language, that I call 'dynamic', but compared 
with Python it might as well be carved in stone!)

-- 
Bartc


From flebber.crue at gmail.com  Sun Nov  8 19:24:30 2015
From: flebber.crue at gmail.com (Sayth Renshaw)
Date: Sun, 8 Nov 2015 16:24:30 -0800 (PST)
Subject: Is there an archive of the gohlke python binaries on windows
In-Reply-To: <mailman.123.1446978638.16136.python-list@python.org>
References: <cce5b84f-6ade-4e77-8bda-8354d80adb74@googlegroups.com>
 <mailman.123.1446978638.16136.python-list@python.org>
Message-ID: <563752c4-1426-4b8b-ac83-02278f460123@googlegroups.com>

On Sunday, 8 November 2015 21:30:59 UTC+11, Laura Creighton  wrote:
> In a message of Sat, 07 Nov 2015 21:55:32 -0800, Sayth Renshaw writes:
> >Just wondering if there is an archive mirror for these binaries available. i was looking for lxml 3.4.1 and the current version is the latest on the page at 3.4.4 being on windows I cannot build it.
> >
> >http://www.lfd.uci.edu/~gohlke/pythonlibs/
> >
> >Thanks
> >
> >Sayth
> 
> https://pypi.python.org/pypi/lxml/3.4.1
> 
> Laura

Thanks Laura but that fails to install because I uninstalled visual studio and its compiler.

Sayth


From ben+python at benfinney.id.au  Sun Nov  8 19:26:08 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 11:26:08 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
Message-ID: <85y4e8ggrj.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> Testing/mocking is a completely separate consideration (eg you can
> inject a shadow for a built-in name)

Not for the purpose of making compiler optimisations, as BartC is
advocating.

The compiler definitely should not treat ?is this code part of a test
suite?? as a relevant criterion for deciding what optimisation. We
should certainly not have a compiler that makes needless difference to
code behaviour under test conditions versus non-test conditions.

So, since those optimisations would cripple perfectly normal test code,
that should be sufficient to quash the desire to make them.

-- 
 \       ?If you define cowardice as running away at the first sign of |
  `\   danger, screaming and tripping and begging for mercy, then yes, |
_o__)               Mr. Brave man, I guess I'm a coward.? ?Jack Handey |
Ben Finney



From flebber.crue at gmail.com  Sun Nov  8 19:33:12 2015
From: flebber.crue at gmail.com (Sayth Renshaw)
Date: Sun, 8 Nov 2015 16:33:12 -0800 (PST)
Subject: Python version of Ruby devkit - Advice On library compilation
Message-ID: <0fa52e1f-4983-4238-95a2-4b0558fb9738@googlegroups.com>

Hi

I was wondering if there is a reason that we on windows with python do not have a version of Ruby devkit for python. 

Is it just for historical reason of life before pip became the package manager and released with python? 
I can't find the actual post in SO it came off this discussion http://stackoverflow.com/a/13445719/461887 regarding vcvarsall and related python packaging queries. 

I know it wouldn't solve all pain points as I don't believe(could be wrong here) it would be unable to include Atlas compilation for some scientific libraries but it would be able to compile most targets and reduce the need for alternate implementations, like conda.

Not that there is anything wrong with conda at all except you need to rebuild most of the libraries in binstar to use them, but its virtualenv feature is nice and if you use R its good to.

Someone more windows and library build savvy is this something easily achievable for windows and would it help?

Cheers

Sayth


From steve at pearwood.info  Sun Nov  8 19:35:04 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 09 Nov 2015 11:35:04 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.124.1446985683.16136.python-list@python.org>
Message-ID: <563fea3a$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 11:28 pm, Chris Angelico wrote:

> On Sun, Nov 8, 2015 at 10:19 PM, BartC <bc at freeuk.com> wrote:
>> I've never understood why this seems to be necessary in Python. Why do
>> names have to be looked up? (I'm assuming this is searching by name in
>> some sort of table.)
> 
> Yes, if by "searching" you include hash-table lookup. A CPython
> dictionary is a *highly* optimized data structure, specifically
> because it's used virtually everywhere (I understand Lua's "table"
> type has similar optimizations for the same reason). In the common
> case, where your names come from literal text in the module, the
> strings used for the lookup will be interned constants, and their
> hashes will have been precalculated and stored, so the lookup is
> pretty easy. So it's a constant-time operation, and while that
> constant may be larger than a simple offset-and-fetch, it's still
> pretty fast in the overall scheme of things.

*Usually*.

There are pathological cases -- if you're unlucky enough, or malicious
enough, to have a whole lot of names with the same hash value, the look-up
degrades to a linear search.

More importantly, consider the case of a function referring to a variable
named "spam". In principle, at least, it may need to:

- search the local namespace;
- search the namespace of one or more enclosing functions;
- search the global namespace;
- search the built-in namespace;

before locating the variable's value. In practice, most Python
implementations will provide at least one optimization: local variables are
recognised and searched using an offset-and-fetch model.

Similarly for method calls: spam.eggs needs to:

- search the instance dict and slots;
- search the class dict;
- search the dict for each additional superclass;

where searching involves more than just a hash table lookup. It also
involves checking the classes for __getattribute__ and __getattr__ methods,
checking for descriptors, and more. The whole lookup process is quite
complicated, and little of it can be done at compile time.



-- 
Steven



From rosuav at gmail.com  Sun Nov  8 19:36:23 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 11:36:23 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <85y4e8ggrj.fsf@benfinney.id.au>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
Message-ID: <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:26 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>
>> Testing/mocking is a completely separate consideration (eg you can
>> inject a shadow for a built-in name)
>
> Not for the purpose of making compiler optimisations, as BartC is
> advocating.
>
> The compiler definitely should not treat ?is this code part of a test
> suite?? as a relevant criterion for deciding what optimisation. We
> should certainly not have a compiler that makes needless difference to
> code behaviour under test conditions versus non-test conditions.
>
> So, since those optimisations would cripple perfectly normal test code,
> that should be sufficient to quash the desire to make them.

But I distinguish between crippling *performance* and crippling
*functionality*. If the compiler optimizations are defeated, so the
test suite falls back on the slow path, that means your tests run
slower. Unless you're testing the optimizer itself, this shouldn't be
a problem.

This is broadly the same kinds of optimizations that Fat Python is
playing with. Effectively, what it says is "I think that 'len' is this
object", and then it guards the fast path with a quick check for
validity. So if you go in and change something, the result is that the
slow path gets used instead.

The question then is whether it's worth the optimization effort. Will
the slow path be penalized more than the fast path gains? Will the
code complexity introduce more bugs? The same consideration comes up
in JavaScript/ECMAScript (where object attributes can also be created
dynamically), and I know some interpreters have been written to do a
slot-based lookup, so the concept does have at least some merit.

Personally, I'm dubious about the value of this in CPython; but I'm
willing to be persuaded.

ChrisA


From rosuav at gmail.com  Sun Nov  8 19:37:12 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 11:37:12 +1100
Subject: Python version of Ruby devkit - Advice On library compilation
In-Reply-To: <0fa52e1f-4983-4238-95a2-4b0558fb9738@googlegroups.com>
References: <0fa52e1f-4983-4238-95a2-4b0558fb9738@googlegroups.com>
Message-ID: <CAPTjJmr5OOxUNq7nNtffSPS+vsXySch8QfgQgcQwcusjqugzog@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:33 AM, Sayth Renshaw <flebber.crue at gmail.com> wrote:
> I was wondering if there is a reason that we on windows with python do not have a version of Ruby devkit for python.
>

Many of us here don't use Ruby. Can you elaborate on what "devkit" does, please?

ChrisA


From ben+python at benfinney.id.au  Sun Nov  8 19:50:57 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 11:50:57 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
Message-ID: <85twowgfm6.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> On Mon, Nov 9, 2015 at 11:26 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> > Chris Angelico <rosuav at gmail.com> writes:
> >
> >> Testing/mocking is a completely separate consideration (eg you can
> >> inject a shadow for a built-in name)
> >
> > Not for the purpose of making compiler optimisations, as BartC is
> > advocating. [?] since those optimisations would cripple perfectly
> > normal test code, that should be sufficient to quash the desire to
> > make them.
>
> But I distinguish between crippling *performance* and crippling
> *functionality*. If the compiler optimizations are defeated, so the
> test suite falls back on the slow path, that means your tests run
> slower. Unless you're testing the optimizer itself, this shouldn't be
> a problem.

You misunderstand me. I'm not saying the optimisations would be
crippled. I am saying that, in order to achieve those optimisations, the
*test code* would be crippled.

I am pointing out that the assumption necessary for the optimisation
BartC is advocating ? the optimisation of module attributes to be
immutable after compilation ? depends on crippling the *functionality*
needed for many uses, including test code uses.

Since the compiler should not be in the position of deciding whether
code is test code or not, it cannot use that criterion to decide whether
to enable or disable the optimisation.

So either the optimisation should never be enabled (my perference), or
test code will unwittingly be crippled by the assumptions needed for
that optimisation.

-- 
 \     ?We are all agreed that your theory is crazy. The question that |
  `\      divides us is whether it is crazy enough to have a chance of |
_o__)            being correct.? ?Niels Bohr (to Wolfgang Pauli), 1958 |
Ben Finney



From wangq at travelsky.com  Sun Nov  8 19:52:42 2015
From: wangq at travelsky.com (wangq at travelsky.com)
Date: Mon, 9 Nov 2015 08:52:42 +0800
Subject: Question about math.pi is mutable
References: <201511061033583772468@travelsky.com>, 
 <CAPTjJmr7brs6B=oD9m2bEk_Mm7wUTVKWU-gxqgAqDLV4diOdzw@mail.gmail.com>
Message-ID: <201511090852416321002@travelsky.com>

Hi, Chris Angelico ,

    Thank you for your help !  :-)
 
From: Chris Angelico
Date: 2015-11-06 18:30
To: wangq at travelsky.com
CC: python-list
Subject: Re: Question about math.pi is mutable
On Fri, Nov 6, 2015 at 1:33 PM, wangq at travelsky.com <wangq at travelsky.com> wrote:
> Hello, python-list guys:
>
>     I am a newbie of python from Beijing. China.
>     I have a question about "math.pi".
>     As you can see in the attachment, why i can modify "math.pi"?
>     (in "mathmodule.c" "pi" is a "static const double")
>
> Thank you in advance!
>
> Best Wishes?
 
Simply because, in Python, virtually everything can be changed. You're
welcome to go in and say "math.pi = 3" if you like... and then you
accept the consequences of that.
 
There are times when you want to change these sorts of 'constants'.
For example, math.pi is a float; but if you're working with
decimal.Decimal everywhere, it might be useful to replace it with a
corresponding Decimal value:
 
math.pi = decimal.Decimal("3.14159265358979323")
 
And that's perfectly legal.
 
ChrisA
 

From rosuav at gmail.com  Sun Nov  8 19:56:39 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 11:56:39 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <85twowgfm6.fsf@benfinney.id.au>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
Message-ID: <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:50 AM, Ben Finney <ben+python at benfinney.id.au> wrote:
> You misunderstand me. I'm not saying the optimisations would be
> crippled. I am saying that, in order to achieve those optimisations, the
> *test code* would be crippled.
>
> I am pointing out that the assumption necessary for the optimisation
> BartC is advocating ? the optimisation of module attributes to be
> immutable after compilation ? depends on crippling the *functionality*
> needed for many uses, including test code uses.
>
> Since the compiler should not be in the position of deciding whether
> code is test code or not, it cannot use that criterion to decide whether
> to enable or disable the optimisation.
>
> So either the optimisation should never be enabled (my perference), or
> test code will unwittingly be crippled by the assumptions needed for
> that optimisation.

Hmm, then I was misunderstanding what BartC was advocating. I didn't
think it would *fail* in the presence of dynamic attributes, but
merely *perform suboptimally* (and presumably worse than current
CPython). If it does indeed require crippling the functionality, then
I agree, this is a bad idea.

ChrisA


From steve at pearwood.info  Sun Nov  8 19:58:11 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 09 Nov 2015 11:58:11 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me> <87mvuowvzo.fsf@elektro.pacujo.net>
 <n1nfmf$qta$1@dont-email.me>
Message-ID: <563fefa6$0$1595$c3e8da3$5496439d@news.astraweb.com>

On Sun, 8 Nov 2015 11:39 pm, BartC wrote:


>> shutil.copyfileobj(Source(), Dest())
>> ========================================================================
> 
> OK, so here, it is necessary to resolve "copyfileobj" by seeing if
> "shutil" is something that contains a name "copyfileobj" that happens to
> be a method.

Correct.

> Is this the lookup you're talking about, and is it done using the actual
> string "copyfileobj"? If so, does it need to be done every single time
> this line is executed? It would extraordinarily inefficient if that was
> the case.

That's not what Marko was referring to, but you are correct, it is done
using the string "copyfileobj". And it has to be done every single time,
since you cannot be sure that the lookup will always return the same
object, or even whether it will always succeed. For example, here is a
self-destructing method:


class X:
    counter = 0
    def method(self):
        self.counter += 1
        if self.counter == 3:
            del X.method
        msg = "This method will self-destruct in %d calls."
        return msg % (3 - self.counter)


But you are wrong to describe this as "extraordinarily inefficient". It is
certainly efficient enough to be practical: inefficient or not, Python is
used for many thousands of practical applications. It is only about a
factor of 100 times slower than C or Java, and the PyPy optimizing compiler
averages ten times faster (and, occasionally, approaches or even exceeds
the speed of similar C or Java code). When performance is critical, you can
often locate the bottlenecks and turn that into C or Fortran code.

Ruby, which is even more flexible than Python in some ways, is even slower,
and yet even Ruby is still fast enough to be practical for many tasks.

And remember too that some of the speed of Java (and especially C) is gained
at the expense of:

- prohibiting the developer from doing certain things;
- restricting the range of values you can use;
- making significant assumptions about correctness;
- avoiding actually checking those assumptions;
- and in the case of C, by outright *ignoring the code you write* if you
inadvertently violate those assumptions.



-- 
Steven



From ben+python at benfinney.id.au  Sun Nov  8 20:04:55 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 09 Nov 2015 12:04:55 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
Message-ID: <85pozkgeyw.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> Hmm, then I was misunderstanding what BartC was advocating. I didn't
> think it would *fail* in the presence of dynamic attributes, but
> merely *perform suboptimally* (and presumably worse than current
> CPython).

There isn't a way for the compiler to *know*, in all cases, whether
module attributes will be updated during the lifetime of the program
(short of, as pointed out elsewhere, running the entire program under
all possible conditions).

So the optimisation can't be applied by the compiler without risking
breaking perfectly valid code.

That is enough, IMO, to kill the proposal; if the compiler could break
*any* valid code, it's no longer a Python compiler.

-- 
 \           ?If [a technology company] has confidence in their future |
  `\      ability to innovate, the importance they place on protecting |
_o__)     their past innovations really should decline.? ?Gary Barnett |
Ben Finney



From steve at pearwood.info  Sun Nov  8 21:23:06 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 09 Nov 2015 13:23:06 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.147.1447016469.16136.python-list@python.org>
 <n1oiik$90r$1@dont-email.me>
Message-ID: <5640038b$0$1612$c3e8da3$5496439d@news.astraweb.com>

On Mon, 9 Nov 2015 09:35 am, BartC wrote:

> Suppose this is the python program:
> 
> import m
> a=10
> b=20
> c=30
> m.f()
> 
> The set of global names the compiler knows will be ("m","a","b","c").

Wrong. Up to the line "c=30", the set of names the compiler can infer are m,
a, b and c. Once the line "m.f()" executes, *all bets are off*. The
compiler can no longer infer *anything* about those names. In principle,
m.f may have reached into the globals and deleted *any* of the names,
including itself.


> I don't believe code can remove these names (that would cause problems).

Of course names can be removed. There's even a built-in statement to do
so: "del".

Deleting names from namespaces is a moderately common thing to do.


> You say the set of global names can be added to - after this lot, but I
> can't see that the first four are going to change.

Of course they can change.


> Therefore these names could be referred to by index.

Perhaps. But that adds significant complexity to the compiler, and the
performance benefits *in practice* may not be as good as you imagine. After
all, there is usually far more to real programs than just getting and
setting names.

Nevertheless, such indexed name lookups do have the potential to save time,
and in fact that's what CPython already does with local variables. We can
get a *rough* indication of how big a difference this micro-optimization
makes by disabling it. Unfortunately, this only works in Python 2 -- in
Python 3, you can no longer defeat the local variable optimization.


def unopt():
    from math import *  # Defeats the local variable optimization.
    x = sin; x = cos; x = tan; x = exp; x = pi
    x = e; x = trunc; x = log; x = hypot; x = sqrt
    return

def opt():
    from math import sin, cos, tan, exp, pi, e, trunc, log, hypot, sqrt
    x = sin; x = cos; x = tan; x = exp; x = pi
    x = e; x = trunc; x = log; x = hypot; x = sqrt
    return

from timeit import Timer
t1 = Timer("unopt()", setup="from __main__ import unopt")
t2 = Timer("opt()", setup="from __main__ import opt")

# Best of five trials of 1,000,000 calls each.
print min(t1.repeat(repeat=5))
print min(t2.repeat(repeat=5))


When I run this code, I get

16.5607659817 seconds for unopt, and 3.58955097198 seconds for opt. That's a
significant difference. But remember that not all of that difference is due
to the name lookups (unopt also imports more stuff), and also remember that
this is a pretty unrealistic benchmark. Real functions do more than just
look up a variable name over and over.


> Attributes are harder because they are more of a free-for-all, but
> suppose you do have m.f().
> 
> "m" is easy, it's entry 0 in the global table for this module, so no
> lookup-by-name is needed. You examine it, and it's a module.
> 
> It's now necessary to find f within the global table for m. This is
> where it gets tricky if you want to avoid a lookup. And I expect you
> will say that any code can randomly add names within the global table of
> m.

Of course it can. It can even add names to builtins.

Oh, and you don't know that m is a module until you inspect it at runtime.
It could be any object.



> But bear with me. Suppose the interpreter were to maintain a table for
> each static (not runtime) attribute encountered in the source code. The
> compile can produce empty tables for the attributes it's seen. In this
> case the table for "f" would be empty: (). The compiler will also
> produce a list of such tables for all attributes.

I have no idea how well this implementation would work. My guess is that if
you look at, say, Nuitka, it may perform optimizations like this. (The aim
of Nuitka is to be a static optimizing compiler.) PyPy may do things like
this too, using a JIT optimizing compiler. PyPy is capable of far more than
such simple optimizations.

As I have argued all along, it is certainly not true that Python's
dynamicism prevents all such optimizations. It just makes them harder.


-- 
Steven



From lac at openend.se  Sun Nov  8 21:41:07 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 09 Nov 2015 03:41:07 +0100
Subject: [Ubuntu] PyQt5
In-Reply-To: <n1okg2$da7$1@ger.gmane.org>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
 <n1okg2$da7$1@ger.gmane.org>
Message-ID: <201511090241.tA92f7jZ008906@fido.openend.se>

In a message of Sun, 08 Nov 2015 18:05:32 -0500, Terry Reedy writes:
>On 11/8/2015 11:03 AM, Andrew Diamond wrote:
>> On Saturday, November 7, 2015 at 10:13:25 PM UTC-5, Andrew Diamond
>> wrote:
>>> Hi!
>>>
>>> I'm fairly new to Python, and installed pyqt5 and began working
>>> through the examples at http://zetcode.com/gui/pyqt5/menustoolbars/
>>> However, whenever I click one of the buttons or menus in the
>>> example apps I run that is supposed to quit the application, it
>>> locks up.
>
>What is 'it'?  And what does 'lock up' mean?  Did the gui freeze and not 
>disappear?  Or did IDLE itself freeze, and even the menu quit working?
>
>>> This happens with all the examples I installed that
>>> handle code to quit the app.
>>>
>>> Running Ubuntu 15.10, and installed pyqt5 via:
>>>
>>> sudo apt-get install python3-pyqt5 sudo apt-get install qtcreator
>
>> I just read somewhere that the issue could be because I was trying to
>> run these examples from within Idle.
>
>I am an IDLE maintainer.  Am I to take it that everything ran fine 
>before you tried to quit?  If not, I would want to know why and try to fix.
>
>If you run tut.py from an IDLE editor, IDLE tries to run it the same as 
>if you ran it at a console in the tut.py directory with 'python3 -i 
>tut.py'.  I can imagine that there might be a problem with the 
>transition from gui mode to interactive shell mode, though it works for 
>tkinter apps.  You said 'python3 tut.py' works.  What happens if you add 
>the '-i' option?  I'd like to know if the transition problem is in 
>(Py)qt5 or in IDLE's simulation of '-i'.
>
>-- 
>Terry Jan Reedy

I suspect that Qt and Idle are disagreeing as to who gets to have the
main thread around here.

Laura



From flebber.crue at gmail.com  Sun Nov  8 23:00:24 2015
From: flebber.crue at gmail.com (Sayth Renshaw)
Date: Sun, 8 Nov 2015 20:00:24 -0800 (PST)
Subject: Python version of Ruby devkit - Advice On library compilation
In-Reply-To: <mailman.157.1447029440.16136.python-list@python.org>
References: <0fa52e1f-4983-4238-95a2-4b0558fb9738@googlegroups.com>
 <mailman.157.1447029440.16136.python-list@python.org>
Message-ID: <5e8b9af2-bf8f-4cb4-be24-3b74c20e99e4@googlegroups.com>

This is an exert 

DevKit Overview
The DevKit is a toolkit that makes it easy to build and use native C/C++ extensions such as RDiscount and RedCloth for Ruby on Windows.

Because on Windows with python libraries like lxml will fail with a vcvarsall error based on different c++ compilers. 

Sayth


From rosuav at gmail.com  Sun Nov  8 23:21:43 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 15:21:43 +1100
Subject: Python version of Ruby devkit - Advice On library compilation
In-Reply-To: <5e8b9af2-bf8f-4cb4-be24-3b74c20e99e4@googlegroups.com>
References: <0fa52e1f-4983-4238-95a2-4b0558fb9738@googlegroups.com>
 <mailman.157.1447029440.16136.python-list@python.org>
 <5e8b9af2-bf8f-4cb4-be24-3b74c20e99e4@googlegroups.com>
Message-ID: <CAPTjJmpMZcZFbxsLzy2syirpDXbFuBgOL-Aj0ePjyOShd_e+-Q@mail.gmail.com>

On Mon, Nov 9, 2015 at 3:00 PM, Sayth Renshaw <flebber.crue at gmail.com> wrote:
> This is an exert
>
> DevKit Overview
> The DevKit is a toolkit that makes it easy to build and use native C/C++ extensions such as RDiscount and RedCloth for Ruby on Windows.
>
> Because on Windows with python libraries like lxml will fail with a vcvarsall error based on different c++ compilers.

Ah okay.

The normal way to install Python extensions on Windows is to get a
precompiled binary. That way, you don't have to worry about compilers
at all. In the case of lxml, you can get them straight off PyPI:

https://pypi.python.org/pypi/lxml/3.4.4

I don't have a Windows system to test with, but 'pip' should be able
to go fetch them for you. There does seem to be a bit of a hole,
though: there's an installer that targets CPython 3.2, but nothing
newer. Fortunately, there's another good place to find Windows
binaries - this unofficial (but fairly trustworthy) site:

http://www.lfd.uci.edu/~gohlke/pythonlibs/#lxml

Binaries targeting CPython 2.7, 3.3, 3.4, and 3.5 are all there.
Download the appropriate one (due to compiler differences, you MUST
pick the one for your CPython version, or it won't work), and use
easy_install on the egg file.

Actually installing a build chain on Windows is such a pain that it's
usually easier to fiddle around with binaries than to build from
source. That's probably why there's no Python DevKit - even with that
kind of thing, getting all your deps right would be a pain.

ChrisA


From greg.ewing at canterbury.ac.nz  Mon Nov  9 03:29:39 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 09 Nov 2015 21:29:39 +1300
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.155.1447028787.16136.python-list@python.org>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <mailman.155.1447028787.16136.python-list@python.org>
Message-ID: <dab3rkFi9vaU1@mid.individual.net>

Ben Finney wrote:

> We
> should certainly not have a compiler that makes needless difference to
> code behaviour under test conditions versus non-test conditions.

Indeed. Volkswagen tried a version of that recently,
and it didn't end well...

-- 
Greg


From Lim_Ee_Hai at ite.edu.sg  Mon Nov  9 04:17:08 2015
From: Lim_Ee_Hai at ite.edu.sg (Lim_Ee_Hai at ite.edu.sg)
Date: Mon, 9 Nov 2015 17:17:08 +0800
Subject: Probelm with installing Python 3.5.0
Message-ID: <OF84B22FD7.66D6E3FC-ON48257EF8.003299AE-48257EF8.00330218@ite.edu.sg>

Dear Python organisation staff,

 The Python 3.5.0 was successfully installed. But encountered missing dll 
upon running the program.



My computer is running on Win 7.

Any advise to resolve this issue?

Rgds

LIM Ee Hai 
Senior Lecturer / Electronics Engineering,  School of Electronics & 
Info-Comm Technology
ITE College Central, 2 Ang Mo Kio Drive, Singapore 567720
Tel: +65 68797886 | Fax: +65 6580 5300 | Website: www.ite.edu.sg

 
Confidentiality Caution: If you are not the intended recipient of this 
communication, please do not retain,
use, disclose, disseminate, distribute or copy the contents to any person, 
as it may be unlawful.
 

From harvesting at makes.email.invalid  Mon Nov  9 04:58:10 2015
From: harvesting at makes.email.invalid (Jussi Piitulainen)
Date: Mon, 09 Nov 2015 11:58:10 +0200
Subject: using binary in python
References: <mailman.164.1447060794.16136.python-list@python.org>
Message-ID: <lf5ziynxznx.fsf@ling.helsinki.fi>

kent nyberg writes:

[- -]
> Well, lets assume I want to write and read binary.  How is it done?
[- -]

You open the file with mode "wb" (to write binary) or "rb" (to read
binary), and then you write or read bytes (eight-bit units).

   >>> data = '"bin??ridataa"\n'.encode('utf-8')
   >>> f = open('roska.txt', 'wb')
   >>> f.write(data)
   17
   >>> f.close()

The .encode methods produced a bytestring, which Python likes to display
as ASCII characters where it can and in hexadecimal where it cannot:

   >>> data
   b'"bin\xc3\xa4\xc3\xa4ridataa"\n'

An "octal dump" in characters (where ASCII, otherwise apparently octal)
and the corresponding hexadecimal shows that it is, indeed, these bytes
that ended up in the file:

$ od -t cx1 roska.txt 
0000000   "   b   i   n 303 244 303 244   r   i   d   a   t   a   a   "
         22  62  69  6e  c3  a4  c3  a4  72  69  64  61  74  61  61  22
0000020  \n
         0a
0000021

In UTF-8, the letter '?' is encoded as the two bytes c3 a4 (aka 303 244,
and you are welcome to work them out in binary, or even in decimal
though that is less transparent when what you want to see is bits). In
other encodings, there might be just one byte for that letter, and there
are even encodings where the ASCII letters would be different bytes.

Fixed-sized numbers (32-bit, 64-bit integers and floating point numbers
have conventional representations as groups of four or eight bytes). You
could interpret parts of the above text as such instead.


From tjreedy at udel.edu  Mon Nov  9 05:24:43 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 9 Nov 2015 05:24:43 -0500
Subject: [Ubuntu] PyQt5
In-Reply-To: <201511090241.tA92f7jZ008906@fido.openend.se>
References: <d453cf4b-7a30-4b2c-9bff-53d488552671@googlegroups.com>
 <7056c802-308b-4d5c-961d-052ef2671633@googlegroups.com>
 <n1okg2$da7$1@ger.gmane.org> <201511090241.tA92f7jZ008906@fido.openend.se>
Message-ID: <n1ps9i$h2c$1@ger.gmane.org>

On 11/8/2015 9:41 PM, Laura Creighton wrote:
> In a message of Sun, 08 Nov 2015 18:05:32 -0500, Terry Reedy writes:

>>> I just read somewhere that the issue could be because I was trying to
>>> run these examples from within Idle.

First let me note that a) IDLE is meant for learning Python and 
developing Python programs, and b) IDLE using tkinter/tcl/tk and 
programs that introspect too deeply or interact with hardware can 
interfere with each other.  I recently added
https://docs.python.org/3/library/idle.html#idle-console-differences
to document some differences from console python.

Can IDLE be used for developing GUI programs?  In the case of tkinter, 
yes.  For 3.x, at least, I believe there are advantages over plain 
editors.  For other gui packages, I would like to know what limitations 
or problems there are so I can warn people against trying to do things 
that will not work.  Hence the questions below.

>> I am an IDLE maintainer.  Am I to take it that everything ran fine
>> before you tried to quit?  If not, I would want to know why and try to fix.
>>
>> If you run tut.py from an IDLE editor, IDLE tries to run it the same as
>> if you ran it at a console in the tut.py directory with 'python3 -i
>> tut.py'.  I can imagine that there might be a problem with the
>> transition from gui mode to interactive shell mode, though it works for
>> tkinter apps.  You said 'python3 tut.py' works.  What happens if you add
>> the '-i' option?  I'd like to know if the transition problem is in
>> (Py)qt5 or in IDLE's simulation of '-i'.

> I suspect that Qt and Idle are disagreeing as to who gets to have the
> main thread around here.

I doubt this is the specific problem because user code, here invoking 
pyqt and qt, are run in a separate process.  While it is running, I 
believe the only Idle code that would run is in the substitute 
stdin/out/err, which are only used if the user code calls input, print, 
or .write() or raises.  Instead of

 > python3 -i mypyqt.py

at a console prompt, IDLE starts a subprocess with

 > python -m idlelib.run mypyqt.py

The latter sets up socket communication, a locals namespace that 
imitates __main__, and a few other things and then runs
    exec(open(mypyqt.py).read(), locals).

I can imagine a few different ways things could get messed up, which is 
why I asked the specific questions I did.  For instance, if a program 
rebinds the standard stream but does not restore them, because it 
assumes that exiting the program mean exiting the process (as would 
normally be the case with a gui program), then the '-i' option and the 
IDLE simulation thereof may not work.

In thinking about this, I realized that I could test that idlelib.run at 
least works with all stdlib modules by running the entire CPython test 
suite in the execution process.  I already run idle tests in IDLE while 
developing them, but had never thought about the fact that I was testing 
the run module also.

-- 
Terry Jan Reedy



From motoom at xs4all.nl  Mon Nov  9 05:40:20 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Mon, 9 Nov 2015 11:40:20 +0100
Subject: using binary in python
In-Reply-To: <20151108212706.GA29701@z-sverige.nu>
References: <20151108212706.GA29701@z-sverige.nu>
Message-ID: <BF049F21-136E-442B-A466-FFC7CA1C390A@xs4all.nl>


> On 08 Nov 2015, at 22:27, kent nyberg <kent at z-sverige.nu> wrote:
> 
> Well, lets assume I want to write and read binary.  How is it done?

With the functions 'open()' and 'read()' and 'write()'. If you're on Windows, don't forget to include a 'b' in the mode string of the open() call, otherwise Python will assume that you're opening a text file.

You also might want to look into the 'struct' module, functions 'pack()' and 'unpack()'. They convert python values to their binary representation which is used in binary files.

Greetings,





From marko at pacujo.net  Mon Nov  9 05:56:08 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 09 Nov 2015 12:56:08 +0200
Subject: using binary in python
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
Message-ID: <87d1vjigqf.fsf@elektro.pacujo.net>

Michiel Overtoom <motoom at xs4all.nl>:

> If you're on Windows, don't forget to include a 'b' in the mode string
> of the open() call, otherwise Python will assume that you're opening a
> text file.

Python has brought that blessing to other operating systems, as well.

One of the principal UNIX innovations was to see files as simple byte
sequences. The operating system would place no semantics on the meaning
or structure of the bytes.

Python presents a different concept of a file; Python files are either
text files or binary files. The dichotomy is built on top of the UNIX
file system. However, the Python model "leaks" in that nothing prevents
you from opening a binary file as a text file or vice versa.


Marko


From rosuav at gmail.com  Mon Nov  9 06:04:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 22:04:26 +1100
Subject: using binary in python
In-Reply-To: <87d1vjigqf.fsf@elektro.pacujo.net>
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmr7h0aeaJ5Cay=TPee_HAChsNPikR5iBFjQ1EVOwr+HRQ@mail.gmail.com>

On Mon, Nov 9, 2015 at 9:56 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> One of the principal UNIX innovations was to see files as simple byte
> sequences. The operating system would place no semantics on the meaning
> or structure of the bytes.

And you also want to see those files as containing "plain text",
right? Unfortunately, those two goals are in conflict. Either a file
is nothing but bytes, or it contains text in some encoding. From the
file system and operating system's points of view, the files are
indeed nothing but bytes; but from the application's point of view,
text is text and bytes is bytes. In Python, a text file is opened with
a specific encoding, and Python handles the encode/decode steps.

ChrisA


From steve at pearwood.info  Mon Nov  9 06:22:13 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 09 Nov 2015 22:22:13 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
Message-ID: <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>

On Mon, 9 Nov 2015 12:04 pm, Ben Finney wrote:

> There isn't a way for the compiler to *know*, in all cases, whether
> module attributes will be updated during the lifetime of the program
> (short of, as pointed out elsewhere, running the entire program under
> all possible conditions).
> 
> So the optimisation can't be applied by the compiler without risking
> breaking perfectly valid code.

It's not 1980 any more, compiler technology has come a long way since the
Dragon Book. In the words of Steve Yegge, describing the attitudes of C++
developers who insist that no other language (and especially dynamic
languages) can be sufficiently fast:

"And so, you know, their whole argument is based on these fallacious, you
know, sort of almost pseudo-religious... and often it's the case that
they're actually based on things that used to be true, but they're not
really true anymore"

http://steve-yegge.blogspot.com.au/2008/05/dynamic-languages-strike-back.html


The compiler doesn't need to decide in advance whether or not the module
attributes have been changed. It can decide that at runtime, just before
actually looking up the attribute. In pseudo-code:

    if attribute might have changed:
        use the slow path just like today
    else:
        use the optimized fast path


The PyPy FAQs suggest that PyPy is capable of fast, optimized attribute
access in this fashion, using a guard to ensure the fast path is taken only
when ?this class attribute was not modified?. I'm not a compiler expert,
but I would expect that this sort of technology could be adapted to do the
same for module attributes.

http://doc.pypy.org/en/latest/faq.html

Such optimizations don't come for free: PyPy has taken a lot of development
effort, and some funding from the EU. And PyPy is more memory-hungry than
CPython. But that's just the same old trade-off that programmers have been
doing since time immemorial: you can save time, or you can save space, but
you can rarely save both together.

Other dynamic languages also have proven fast implementations: for decades,
Lisp (dynamic) and Fortran (static) were the two fastest languages around.
If Lisp has fallen behind, it is not because it is dynamic, but because
nobody is working on optimizing it. What was optimal in 1975 may not be
optimal on today's hardware.

Javascript and PHP also have extremely fast versions. Javascript's V8
compiler is actually two compilers in one, and it automatically swaps over
to the optimizing compiler when it is appropriate:

http://jayconrod.com/posts/54/a-tour-of-v8-crankshaft-the-optimizing-compiler

When Crankshaft's assumptions are violated, the compiler automatically swaps
back to running the unoptimized code.

Facebook took a different approach with HipHop, using a JIT language
translator that takes PHP and outputs compiled C++ code:

https://www.facebook.com/notes/facebook-engineering/hiphop-for-php-move-fast/280583813919

HipHop is perhaps not the best example, as it does give up some of the most
dynamic features of PHP, such as eval. The post above isn't clear whether
using such features is prohibited, or merely falls back on the slow,
regular PHP interpreter when you use them.




-- 
Steven



From artyprog at gmail.com  Mon Nov  9 07:21:14 2015
From: artyprog at gmail.com (Salvatore DI DIO)
Date: Mon, 9 Nov 2015 04:21:14 -0800 (PST)
Subject: Calulation in  lim  (1  + 1 /n) ^n  when  n -> infinite
Message-ID: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>

Hello,

I was trying to show that this limit was 'e'
But when I try large numbers I get errors

def lim(p):
    return math.pow(1 + 1.0 / p , p)

>>> lim(500000000)
2.718281748862504
>>> lim(900000000)
2.7182820518605446  !!!!


What am i doing wrong ?

Regards


From bc at freeuk.com  Mon Nov  9 07:22:22 2015
From: bc at freeuk.com (BartC)
Date: Mon, 9 Nov 2015 12:22:22 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <5640038b$0$1612$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.147.1447016469.16136.python-list@python.org>
 <n1oiik$90r$1@dont-email.me>
 <5640038b$0$1612$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1q31o$odi$1@dont-email.me>

On 09/11/2015 02:23, Steven D'Aprano wrote:
> On Mon, 9 Nov 2015 09:35 am, BartC wrote:

>> import m
>> a=10
>> b=20
>> c=30
>> m.f()
>>
>> The set of global names the compiler knows will be ("m","a","b","c").
>
> Wrong. Up to the line "c=30", the set of names the compiler can infer are m,
> a, b and c. Once the line "m.f()" executes, *all bets are off*. The
> compiler can no longer infer *anything* about those names. In principle,
> m.f may have reached into the globals and deleted *any* of the names,
> including itself.
>
>
>> I don't believe code can remove these names (that would cause problems).
>
> Of course names can be removed. There's even a built-in statement to do
> so: "del".

I tried this code:

a=10
print (a)

del a
#print (a)

a=20
print (a)

That sort of confirms what you are saying: that names don't even come 
into existence until the first time they are encountered. They don't 
just contain None, or some other value which means the name itself 
exists, but it hasn't been initialised to anything. And that del removes 
the name completely from the set that are known.

That makes Python unlike any other language I've used.

On the other hand, if I put the above code into a function and then call 
the function, attempting to print a just after it's been deleted results in:

  UnboundLocalError: local variable 'a' referenced before assignment

So while local names can presumably be manipulated just like globals, 
that doesn't stop being implemented via a fixed slot in a table.

>> Therefore these names could be referred to by index.
>
> Perhaps. But that adds significant complexity to the compiler,

It would mean that each name needs a flag indicating whether or not it 
has yet been brought into existence by an assignment in the program, or 
has been banished by the use of del.

> and the
> performance benefits *in practice* may not be as good as you imagine. After
> all, there is usually far more to real programs than just getting and
> setting names.

Any programs will consist largely of pushing names and constants (LOAD 
ops), performing some operations on them, and then sometimes popping 
values (STORE ops).

If the names represent complex data, then doing the work on the data 
will dominate the timings. But often it's the 'little' variables that 
hold indices, counts, flags etc that are being frequently loaded and stored.

> def unopt():
>      from math import *  # Defeats the local variable optimization.
>      x = sin; x = cos; x = tan; x = exp; x = pi
>      x = e; x = trunc; x = log; x = hypot; x = sqrt
>      return
>
> def opt():
>      from math import sin, cos, tan, exp, pi, e, trunc, log, hypot, sqrt
>      x = sin; x = cos; x = tan; x = exp; x = pi
>      x = e; x = trunc; x = log; x = hypot; x = sqrt
>      return

> When I run this code, I get
>
> 16.5607659817 seconds for unopt, and 3.58955097198 seconds for opt. That's a
> significant difference.

The optimisation means the code can use LOAD_FAST instead of LOAD_NAME. 
It still uses STORE_FAST instead of STORE_NAME, so perhaps the 
difference could be even more if the unoptimised version had to use 
STORE_NAME.

-- 
Bartc


From rosuav at gmail.com  Mon Nov  9 07:36:54 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 23:36:54 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n1q31o$odi$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.147.1447016469.16136.python-list@python.org>
 <n1oiik$90r$1@dont-email.me>
 <5640038b$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <n1q31o$odi$1@dont-email.me>
Message-ID: <CAPTjJmqkW87UXhQ7z71COqvshSUNCQKOUXnqWhBaDp9CA5QGgw@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:22 PM, BartC <bc at freeuk.com> wrote:
> I tried this code:
>
> a=10
> print (a)
>
> del a
> #print (a)
>
> a=20
> print (a)
>
> That sort of confirms what you are saying: that names don't even come into
> existence until the first time they are encountered. They don't just contain
> None, or some other value which means the name itself exists, but it hasn't
> been initialised to anything. And that del removes the name completely from
> the set that are known.
>
> That makes Python unlike any other language I've used.

It's a direct consequence of the dynamic namespacing. You'll find
similar results in JavaScript/ECMAScript if you play around with
prototype-based inheritance, which has a similar rule ("if the
property isn't here, look at the prototype") to the Python namespacing
rule ("if the name isn't in this namespace, look at the next one
outward").

And you're absolutely correct. Unused names do not "contain None" in
any sense - they utterly do not exist. When you 'del' a name, that
name utterly ceases to exist.

> On the other hand, if I put the above code into a function and then call the
> function, attempting to print a just after it's been deleted results in:
>
>  UnboundLocalError: local variable 'a' referenced before assignment

That's a special case of NameError that was added to make it a bit
easier to track down certain types of bug.

> So while local names can presumably be manipulated just like globals, that
> doesn't stop being implemented via a fixed slot in a table.
>

Global names are simply module attributes, so they can be manipulated
in many ways. Function locals are not; there's no way to say
"current_stack_frame.foo = 2", so there's no need to hack around with
name lookups. (The locals() dictionary isn't meant to be modified, and
changes may or may not have effect on actual local name bindings.)

ChrisA


From harirammanohar159 at gmail.com  Mon Nov  9 07:37:24 2015
From: harirammanohar159 at gmail.com (harirammanohar159 at gmail.com)
Date: Mon, 9 Nov 2015 04:37:24 -0800 (PST)
Subject: help in pexpect multiprocessing
Message-ID: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>

Hi,

I am using multiprocessing with pexpect, issue is whenever i call a function which is having expect(), its throwing error which is genuine as multiple threads are processing it same time (i/o prompt same time by multiple processes..so issues in picture...), so i want to use lock for that section alone to avoid it, but still fails in implementing it...can you help me

username = input('Enter your username: ')
password = getpass.getpass()

s = pxssh.pxssh()
s.login ('host','username','password')
s.sendline ('ps -ef|grep java')
s.prompt(timeout=1)

Try 1:

if condition == 'met':
       np = len(list1)
       p = multiprocessing.Pool(np)
       p.map(stop, [(ds) for ds in list1])

def stop(ds):
        s.sendline ('cd /usr')
        if condition:
                lock = threading.Lock()
                lock.acquire()
                s.expect('Enter username:')
                s.sendline ('user')
                s.expect('Enter password:*')
                s.sendline('pass')
                lock.release()
        s.prompt(timeout=200)
        print('stopped ds...')

Try 2:

if condition == 'met':
        lock = Lock()
        for ds in list1:
                Process(target=stop, args=(ds,lock)).start()

def stop(ds,l):
        s.sendline ('cd /usr')
        if condition:
                l.acquire()
                s.expect('Enter username:')
                s.sendline ('user')
                s.expect('Enter password:*')
                s.sendline('pass')
                l.release()
        s.prompt(timeout=200)
        print('stopped ds...')

Both are giving me same trace..

pexpect.ExceptionPexpect: isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process?

Thanks in Advance


From rosuav at gmail.com  Mon Nov  9 07:45:01 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 9 Nov 2015 23:45:01 +1100
Subject: Calulation in lim (1 + 1 /n) ^n when n -> infinite
In-Reply-To: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
Message-ID: <CAPTjJmo1VgxDF4MdVAAzTa9g+RaPF06q6tVoTNfr2ikihWGMpw@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:21 PM, Salvatore DI DIO <artyprog at gmail.com> wrote:
> I was trying to show that this limit was 'e'
> But when I try large numbers I get errors
>
> def lim(p):
>     return math.pow(1 + 1.0 / p , p)
>
>>>> lim(500000000)
> 2.718281748862504
>>>> lim(900000000)
> 2.7182820518605446  !!!!
>
>
> What am i doing wrong ?
>

Floating point error is going to start becoming a major problem here.
Eventually, 1.0/p will underflow to zero, and you'll simply get a
result of 1.0:

>>> lim(900000000000000000000)
1.0

You could try using decimal.Decimal instead; that can give you rather
more precision. Or if you have a lot of patience, fractions.Fraction.

>>> def lim(p):
    return (1 + decimal.Decimal(1) / p) ** p

>>> lim(500000000)
Decimal('2.718281825740763411884758912')
>>> lim(900000000)
Decimal('2.718281826948888665260445479')
>>> lim(900000000000000000000)
Decimal('2.718281556630875980862943027')

Definitely not perfect yet... but let's crank up the precision.

>>> decimal.getcontext().prec=200
>>> lim(500000000)
Decimal('2.7182818257407634118847589119866382434352189174535941028176465917058364010909850212743201574998148959449308935216863472501568773422911827403060031110458945666576132256505421665510943751730347310393611')
>>> lim(900000000)
Decimal('2.7182818269488886655322736616533366198705073189604924113513719666470682138645212144697520852594221964992741852547403862053248620085931699038380869918694830598723560639286551799819233225160142059050076')
>>> lim(900000000000000000000)
Decimal('2.7182818284590452353587773147812963615153818054494196724217932791045775211554493949916225628968841872263472976692247791433837657091684393783360159727396877123886624050885921242672885287748600658242797')

Now we're starting to get pretty close to the actual value of e. You
can push the precision further if you like; it'll take longer to
calculate, and dump a bigger pile of digits onto your screen, but
it'll be more accurate.

I don't recommend using fractions.Fraction unless you have a really
fast computer and a LOT of patience. It'll take three parts of forever
to get a result... but that result _will_ be perfectly accurate :)

ChrisA


From oscar.j.benjamin at gmail.com  Mon Nov  9 07:50:34 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Mon, 9 Nov 2015 12:50:34 +0000
Subject: Calulation in lim (1 + 1 /n) ^n when n -> infinite
In-Reply-To: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
Message-ID: <CAHVvXxRvgCsfFDLjFudSmj61=Oud7Kc6Heezn1fW7riZUTXX8g@mail.gmail.com>

On 9 November 2015 at 12:21, Salvatore DI DIO <artyprog at gmail.com> wrote:
> I was trying to show that this limit was 'e'
> But when I try large numbers I get errors
>
> def lim(p):
>     return math.pow(1 + 1.0 / p , p)
>
>>>> lim(500000000)
> 2.718281748862504
>>>> lim(900000000)
> 2.7182820518605446  !!!!
>
>
> What am i doing wrong ?

You're performing a floating point calculation and expecting exact results.

Try this:

    >>> lim(10 ** 17)
    1.0

Why does this happen? Well in this case that number is 10**17 and it
turns out that

    >>> 1 + 1.0 / 10**17
    1.0

This is because there aren't enough digits in double precision
floating point to represent the difference between 1 and 1+1e-17. As p
gets larger the addition 1+1.0/p because less and less accurate. The
error in computing that is amplified by raising to a large power p.

You can use more digits by using the decimal module:

    >>> from decimal import Decimal, localcontext
    >>> def lim(p):
    ...     return (1 + 1 / Decimal(p)) ** p
    ...
    >>> with localcontext() as ctx:
    ...     ctx.prec = 100
    ...     lim(10**17)
    ...
    Decimal('2.718281828459045221768878329057436445543726874642885850945607978722364313911964199165598158907225076')

You can also install sympy and find this result symbolically:

    >>> from sympy import Symbol, limit, oo
    >>> p = Symbol('p', integer=True)
    >>> limit((1 + 1/p)**p, p, oo)
    E

--
Oscar


From Cecil at decebal.nl  Mon Nov  9 07:59:01 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 09 Nov 2015 13:59:01 +0100
Subject: Problems connecting to PostgreSQL
References: <87wptt5qg4.fsf@Equus.decebal.nl>
 <mailman.119.1446971807.16136.python-list@python.org>
Message-ID: <87pozj5nxm.fsf@Equus.decebal.nl>

On Sunday  8 Nov 2015 09:36 CET, Chris Warrick wrote:

> On 8 November 2015 at 00:40, Cecil Westerhof <Cecil at decebal.nl> wrote:
>> I followed http://zetcode.com/db/postgresqlpythontutorial/.
>>
>> I used:
>> sudo -u postgres createuser stressTest
>> this create the role, but also gave:
>> could not change directory to "/root": Permission denied
>> and I did not get the questions.
>
> This is not an error, just a warning ? and it comes from sudo,
> postgres doesn?t care. To silence it, you need to work from a
> different directory than /root.  The commands actually worked just
> fine.
>
>> Then I used:
>> sudo -u postgres createdb stressTest -O stressTest
>> This gave also:
>> could not change directory to "/root": Permission denied
>>
>> The database is created, but when I execute: conn =
>> psycopg2.connect(database = postgres_database, user = 'stressTest')
>> I get: psycopg2.OperationalError: FATAL: Peer authentication failed
>> for user "stressTest"
>>
>> What do I need to do to get things working?
>
> You need to configure your PostgreSQL database to use md5
> authentication, and set a password for your user.
>
> # cd /
> # sudo -u postgres psql
> postgres=# ALTER ROLE stressTest WITH PASSWORD 'swordfish';
> postgres=# \q
> # vim /var/lib/postgres/data/pg_hba.conf
>
> Change host settings to look like this:
> # IPv4 local connections:
> host    all             all             127.0.0.1/32            md5
> # IPv6 local connections:
> host    all             all             ::1/128                 md5
>
> Then you can connect using:
>
> conn = psycopg2.connect(database='stressTest', user='stressTest',
> password='swordfish', host='localhost')

Thanks. The file to edit on my system is:
    /var/lib/pgsql/data/pg_hba.conf
and it also looks like I cannot use mixed case. But at the moment I
have it working. I will delve deeper into it later.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From marko at pacujo.net  Mon Nov  9 08:25:55 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 09 Nov 2015 15:25:55 +0200
Subject: using binary in python
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
Message-ID: <8737wfi9ss.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Mon, Nov 9, 2015 at 9:56 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> One of the principal UNIX innovations was to see files as simple byte
>> sequences. The operating system would place no semantics on the
>> meaning or structure of the bytes.
>
> And you also want to see those files as containing "plain text",
> right? Unfortunately, those two goals are in conflict. Either a file
> is nothing but bytes, or it contains text in some encoding. From the
> file system and operating system's points of view, the files are
> indeed nothing but bytes; but from the application's point of view,
> text is text and bytes is bytes. In Python, a text file is opened with
> a specific encoding, and Python handles the encode/decode steps.

So we have this stack:

  +-------------+
  | Application |
  +-------------+
  |   Python    |
  +-------------+
  |    UNIX     |
  +-------------+

The question is, does Python want to be "just a programming language"
that exposes UNIX to the application program? Or does Python want to
present an abstraction different than UNIX? IOW, is the dividing line
between the application and the operating system above or below Python?

It is evident that Python3 has intentionally moved away from the "just a
programming language" view toward Java's write-once-run-everywhere
ideal.


You would be correct that the original UNIX file system model was based
on somewhat of a naive falsity, namely text=ASCII. No matter how you
view it, there is a conflict of sorts. Python3 is trying to pave over
the conflict, but personally I would prefer the programming language
just give me the OS, warts and all.


Marko


From Cecil at decebal.nl  Mon Nov  9 08:40:00 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 09 Nov 2015 14:40:00 +0100
Subject: Using tuple as parameter to a function
Message-ID: <87io5b5m1b.fsf@Equus.decebal.nl>

At the moment I have the following calls:
    do_stress_test(  1, 100)
    do_stress_test(  2, 100)
    do_stress_test(  5, 100)
    do_stress_test( 10, 100)
    do_stress_test( 20, 100)
    do_stress_test( 40, 100)

In principal I want to change it to something like:
    do_stress_test('sqlite',    1, 100)
    do_stress_test('postgres',  1, 100)
    do_stress_test('sqlite',    2, 100)
    do_stress_test('postgres',  2, 100)
    do_stress_test('sqlite',    5, 100)
    do_stress_test('postgres',  5, 100)
    do_stress_test('sqlite',   10, 100)
    do_stress_test('postgres', 10, 100)
    do_stress_test('sqlite',   20, 100)
    do_stress_test('postgres', 20, 100)
    do_stress_test('sqlite',   40, 100)
    do_stress_test('postgres', 40, 100)

But that would not be very dry.

I was thinking about something like:
    values = (( 1, 100), ( 2, 100), ( 5, 100),
               10, 100), (20, 100), (40, 100))
    for value in values:
        do_stress_test('sqlite',   ???)
        do_stress_test('postgres', ???)

Is this possible? If so: what do I put at the place of the '???'?

I could change the second and third parameter to a tuple as the second
parameter, but I prefer three parameters if that would be possible.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From rosuav at gmail.com  Mon Nov  9 08:52:13 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 00:52:13 +1100
Subject: using binary in python
In-Reply-To: <8737wfi9ss.fsf@elektro.pacujo.net>
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpAhAnCyy+YrfH2n=qwwyb40tU17WUhEOWvARqe59cDaQ@mail.gmail.com>

On Tue, Nov 10, 2015 at 12:25 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> So we have this stack:
>
>   +-------------+
>   | Application |
>   +-------------+
>   |   Python    |
>   +-------------+
>   |    UNIX     |
>   +-------------+
>
> The question is, does Python want to be "just a programming language"
> that exposes UNIX to the application program? Or does Python want to
> present an abstraction different than UNIX? IOW, is the dividing line
> between the application and the operating system above or below Python?
>
> It is evident that Python3 has intentionally moved away from the "just a
> programming language" view toward Java's write-once-run-everywhere
> ideal.
>
>
> You would be correct that the original UNIX file system model was based
> on somewhat of a naive falsity, namely text=ASCII. No matter how you
> view it, there is a conflict of sorts. Python3 is trying to pave over
> the conflict, but personally I would prefer the programming language
> just give me the OS, warts and all.

Then you don't want Python. The point of Python is to give you data
types like "list", "dict", "int" (not a machine word but a bignum),
and so on. It's NOT meant to be a thin wrapper around what your OS
offers. Python's string is a Unicode string, not a series of bytes (as
is C's char* type), because human text is better represented as
Unicode than as bytes; so it stands to reason that Python's files
should be able to contain text, since it's the one most obvious
substrate for data storage other than bytes. You get two easy options
(bytes and text), and for everything else you can use a library that's
built on one of those (pickle, json, etc) or a database.

I expect to be able to write idiomatic Python code and have it run on
Windows, Unix, Mac OS, OS/2, or Mozilla Firefox, and do the same
thing. Since those platforms are so very different, supporting all
five is going to mean restricting myself to only those operations that
are common to them all, but I expect those operations to be spelled
the same way and have the same semantics. I do NOT expect that
multiplying 123456 by 654321 will return 80779853376 on some platforms
and 3470442048 on others, nor do I expect "?" to render as a micro
sign on some systems, a box drawing character "?" on others, and as a
capital A with acute "?" on the rest. (Examples not chosen at random.)
Obviously this is an ideal that sometimes can't be achieved perfectly
(Windows vs Unix file system rules, for instance), but it's definitely
part of Python's goal.

If you want C, you know where to get it. Though even C does quite a
bit of papering-over, so maybe you want to be writing assembly code.

ChrisA


From rosuav at gmail.com  Mon Nov  9 08:58:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 00:58:04 +1100
Subject: Using tuple as parameter to a function
In-Reply-To: <87io5b5m1b.fsf@Equus.decebal.nl>
References: <87io5b5m1b.fsf@Equus.decebal.nl>
Message-ID: <CAPTjJmoxWEB=CP5T+=1comyvrDNEcz0mBDmJ-h2a8ALmBLx5jQ@mail.gmail.com>

On Tue, Nov 10, 2015 at 12:40 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> I was thinking about something like:
>     values = (( 1, 100), ( 2, 100), ( 5, 100),
>                10, 100), (20, 100), (40, 100))
>     for value in values:
>         do_stress_test('sqlite',   ???)
>         do_stress_test('postgres', ???)
>
> Is this possible? If so: what do I put at the place of the '???'?
>
> I could change the second and third parameter to a tuple as the second
> parameter, but I prefer three parameters if that would be possible.

Easy! Just unpack the tuple. Two options:

# Unpack in the loop
    for count, size in values:
        do_stress_test('sqlite', count, size)
        do_stress_test('postgres', count, size)

# Unpack in the function call
    for value in values:
        do_stress_test('sqlite', *value)
        do_stress_test('postgres', *value)

Either will work. For what you're doing here, I'd be inclined to the
first option, so you can give the values appropriate names (I'm
completely guessing here that they might be some sort of iteration
count and pool size; use names that make sense to your program); the
other option looks uglier in this particular instance, though it's a
more direct answer to your question.

This is one of Python's best-kept secrets, I think. It's not easy to
stumble on it, but it's so handy once you know about it.

ChrisA


From lac at openend.se  Mon Nov  9 09:27:02 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 09 Nov 2015 15:27:02 +0100
Subject: Probelm with installing Python 3.5.0
In-Reply-To: <OF84B22FD7.66D6E3FC-ON48257EF8.003299AE-48257EF8.00330218@ite.edu.sg>
References: <OF84B22FD7.66D6E3FC-ON48257EF8.003299AE-48257EF8.00330218@ite.edu.sg>
Message-ID: <201511091427.tA9ER2PU000988@fido.openend.se>

In a message of Mon, 09 Nov 2015 17:17:08 +0800, Lim_Ee_Hai at ite.edu.sg writes:
>Dear Python organisation staff,
>
> The Python 3.5.0 was successfully installed. But encountered missing dll 
>upon running the program.
>
>
>
>My computer is running on Win 7.
>
>Any advise to resolve this issue?
>
>Rgds

Which DLL was missing?
I am going to guess wildly and say it was this one:
http://www.microsoft.com/en-us/download/details.aspx?id=48234
because others have reported running into this.

If you are another one, then installing this should make everything work.
But if that isn't the missing one, we need to know what was missing
before we can help you with how to fix it.

Laura


From lac at openend.se  Mon Nov  9 09:31:44 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 09 Nov 2015 15:31:44 +0100
Subject: No subject
In-Reply-To: <SNT406-EAS79923C8C808114EBDA8ACDD5160@phx.gbl>
References: <SNT406-EAS79923C8C808114EBDA8ACDD5160@phx.gbl>
Message-ID: <201511091431.tA9EViXw001459@fido.openend.se>

In a message of Sun, 08 Nov 2015 14:07:24 +0000, Ainoa Guti?rrez Su?rez writes:
>it doesn?twork the entry to Python.
>
>
>
>
>
>
>Enviado desde Correo de Windows


I know it is very difficult trying to communicate in a language that is
not your mother tongue, but we need a lot more information about what
it was that 'didn't work' before we can help you.

Also, you might find it easier to  write to a Spanish Languge Python
mailing list, like this one.

https://lists.es.python.org/listinfo/general

Laura Creighton


From marko at pacujo.net  Mon Nov  9 09:32:28 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 09 Nov 2015 16:32:28 +0200
Subject: using binary in python
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
 <mailman.174.1447077141.16136.python-list@python.org>
Message-ID: <87si4fgs5f.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Nov 10, 2015 at 12:25 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> but personally I would prefer the programming language
>> just give me the OS, warts and all.
>
> Then you don't want Python. The point of Python is to give you data
> types like "list", "dict", "int" (not a machine word but a bignum),
> and so on.

Those examples are out of the scope of the OS abstraction.

> It's NOT meant to be a thin wrapper around what your OS
> offers.

Thankfully, Python hasn't yet taken that away. I can do a lot of nice
things with socket.* and os.* that are unavailable in, say, Java.

> Python's string is a Unicode string, not a series of bytes (as is C's
> char* type), because human text is better represented as Unicode than
> as bytes;

No problem there, either.

> so it stands to reason that Python's files should be able to contain
> text,

Yes, and lists and dicts and ints and objects and all. No problem there.

However, when filenames and sys.stdin deal with text, things are getting
iffy.


Marko


From invalid at invalid.invalid  Mon Nov  9 09:49:15 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Mon, 9 Nov 2015 14:49:15 +0000 (UTC)
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me>
 <mailman.103.1446867842.16136.python-list@python.org>
 <n1kmse$p0o$1@dont-email.me>
 <mailman.104.1446896120.16136.python-list@python.org>
 <n1koqr$v63$1@dont-email.me>
 <mailman.105.1446898544.16136.python-list@python.org>
 <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l851$7e7$2@reader1.panix.com>
 <87y4e9y9j6.fsf@elektro.pacujo.net> <n1mfnf$md6$2@reader1.panix.com>
 <87d1vlx7bg.fsf@elektro.pacujo.net>
Message-ID: <n1qbpb$hn1$1@reader1.panix.com>

On 2015-11-08, Marko Rauhamaa <marko at pacujo.net> wrote:
> Grant Edwards <invalid at invalid.invalid>:
>
>> On 2015-11-07, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> "const" is a very ineffective tool that clutters the code and forces
>>> you to sprinkle type casts around your code.
>>
>> But it allows the compiler to warn you if you pass a pointer to a
>> read-only data to a function that expects a pointer to writable data.
>
> Unfortunately, it doesn't:
>
>========================================================================
> #include <stdio.h>
> #include <string.h>
>
> int main()
> {
>     const char name[] = "Tom";
>     char *p = strstr(name, "Tom");
>     strcpy(p, "Bob");
>     printf("name = %s\n", name);
>     return 0;
> }
>========================================================================
>
>     $ cc -o prog prog.c
>     $ ./prog
>     Bob
>
> No warning.

Yes, there are ways to fool the compiler by converting a const char*
to a plain char* like you did with strstr().  But in my experience
there are plenty of cases where it will generate a useful warning.

> Point is, the consequences of "proper" use of const are so annoying
> even standard library functions would rather grossly abuse it than
> tolerate compiler warnings everywhere.

That's your opinion.

My differs: _I_ find it useful.  I don't have that many problems with
it.  If you don't like it, don't use it -- nobody is forcing you to
declare 'const' variables. 

-- 
Grant






From antoon.pardon at rece.vub.ac.be  Mon Nov  9 09:49:48 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Mon, 09 Nov 2015 15:49:48 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <857flujwy7.fsf@benfinney.id.au>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me> <857flujwy7.fsf@benfinney.id.au>
Message-ID: <5640B28C.6050408@rece.vub.ac.be>

Op 07-11-15 om 04:43 schreef Ben Finney:
> Bartc <bc at freeuk.com> writes:
>
>> Is there no way then in Python to declare:
>>
>>    pi = 3.141519     # etc
>>
>> and make it impossible to override?
> No, and it would be a bad thing if that were something a library author
> could forbid.
>
> Python assumes the programmers using it are consenting adults. Doing
> harmful things is difficult but not forbidden.

I find that to be contradictory. Why should you make something difficult
if you are consenting adults? I also find it important that consenting
adults can choose in how far they can consent. This whole idea of python
assuming we are consenting adults and thus making it impossible to not
consent seems weird.

> Notably, the author of a library should not be forbidding the Pythonic
> ability to change name bindings as needed.

If the author of a library doesn't wish to consent to this I don't see
what is wrong with that.

> If you want to have a different value bound to the name ?math.pi?, and
> you go ahead and explicitly ask to change that binding, the library
> author has no business forbidding that.

I disagree. Maybe the author is willing to freely give support but only
on the condition that the user used the library as it was largely intended.
I see no more reason to allow math.pi to be rebound to another value as
to allow True, False or None to be rebound.

So why should we allow the language designers to forbid the latter but
library authors not the former?



From marco.nawijn at colosso.nl  Mon Nov  9 09:57:39 2015
From: marco.nawijn at colosso.nl (marco.nawijn at colosso.nl)
Date: Mon, 9 Nov 2015 06:57:39 -0800 (PST)
Subject: Using tuple as parameter to a function
In-Reply-To: <mailman.175.1447077487.16136.python-list@python.org>
References: <87io5b5m1b.fsf@Equus.decebal.nl>
 <mailman.175.1447077487.16136.python-list@python.org>
Message-ID: <aca9a260-6c2c-43f6-a7f7-6dee71eb5f51@googlegroups.com>

On Monday, November 9, 2015 at 2:58:21 PM UTC+1, Chris Angelico wrote:
> On Tue, Nov 10, 2015 at 12:40 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> > I was thinking about something like:
> >     values = (( 1, 100), ( 2, 100), ( 5, 100),
> >                10, 100), (20, 100), (40, 100))
> >     for value in values:
> >         do_stress_test('sqlite',   ???)
> >         do_stress_test('postgres', ???)
> >
> > Is this possible? If so: what do I put at the place of the '???'?
> >
> > I could change the second and third parameter to a tuple as the second
> > parameter, but I prefer three parameters if that would be possible.
> 
> Easy! Just unpack the tuple. Two options:
> 
> # Unpack in the loop
>     for count, size in values:
>         do_stress_test('sqlite', count, size)
>         do_stress_test('postgres', count, size)
> 
> # Unpack in the function call
>     for value in values:
>         do_stress_test('sqlite', *value)
>         do_stress_test('postgres', *value)
> 
> Either will work. For what you're doing here, I'd be inclined to the
> first option, so you can give the values appropriate names (I'm
> completely guessing here that they might be some sort of iteration
> count and pool size; use names that make sense to your program); the
> other option looks uglier in this particular instance, though it's a
> more direct answer to your question.
> 
> This is one of Python's best-kept secrets, I think. It's not easy to
> stumble on it, but it's so handy once you know about it.
> 
> ChrisA

If the two numbers are actually conceptually connected, you could
consider passing them as a namedtuple. The function would then 
receive two parameters instead of three. Something like the
following (expanding on ChrisA's example):

from collections import namedtuple

StressParameters = namedtuple('StressParameters', ('count', 'size'))

def do_stress_test(db_backend, stress_parameters):
   # Some useful stuff...
   count = stress_parameters.count
   size = stress_parameters.size
   # More useful stuff

parameters = [StressParameters(1, 100), StressParameters(2,100)]

for p in parameters:
    do_stress_test('sqlite', p)
    do_stress_test('postgres', p)


From Cecil at decebal.nl  Mon Nov  9 10:01:14 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 09 Nov 2015 16:01:14 +0100
Subject: Using tuple as parameter to a function
References: <87io5b5m1b.fsf@Equus.decebal.nl>
 <mailman.175.1447077487.16136.python-list@python.org>
Message-ID: <87egfz5i9x.fsf@Equus.decebal.nl>

On Monday  9 Nov 2015 14:58 CET, Chris Angelico wrote:

> On Tue, Nov 10, 2015 at 12:40 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
>> I was thinking about something like:
>> values = (( 1, 100), ( 2, 100), ( 5, 100),
>> 10, 100), (20, 100), (40, 100))
>> for value in values:
>> do_stress_test('sqlite',   ???)
>> do_stress_test('postgres', ???)
>>
>> Is this possible? If so: what do I put at the place of the '???'?
>>
>> I could change the second and third parameter to a tuple as the
>> second parameter, but I prefer three parameters if that would be
>> possible.
>
> Easy! Just unpack the tuple. Two options:
>
> # Unpack in the loop
> for count, size in values:
> do_stress_test('sqlite', count, size)
> do_stress_test('postgres', count, size)
>
> # Unpack in the function call
> for value in values:
> do_stress_test('sqlite', *value)
> do_stress_test('postgres', *value)
>
> Either will work. For what you're doing here, I'd be inclined to the
> first option, so you can give the values appropriate names (I'm
> completely guessing here that they might be some sort of iteration
> count and pool size; use names that make sense to your program); the
> other option looks uglier in this particular instance, though it's a
> more direct answer to your question.
>
> This is one of Python's best-kept secrets, I think. It's not easy to
> stumble on it, but it's so handy once you know about it.

I remembered the second one, but did not know how it was done. That
was why I asked about it. But the first option is even better. I now
use:
    values = ((  1, 100), (  2, 100), (  5, 100),
              ( 10, 100), ( 20, 100), ( 40, 100),
              #( 80, 100), (160, 100),
              #(160, 200), (160, 400), (160, 800),
          )
    for no_of_threads, no_of_records in values:
        do_stress_test('postgres', no_of_threads, no_of_records)
        do_stress_test('sqlite',   no_of_threads, no_of_records)

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From artyprog at gmail.com  Mon Nov  9 10:13:00 2015
From: artyprog at gmail.com (Salvatore DI DIO)
Date: Mon, 9 Nov 2015 07:13:00 -0800 (PST)
Subject: Calulation in lim (1 + 1 /n) ^n when n -> infinite
In-Reply-To: <mailman.171.1447073105.16136.python-list@python.org>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
 <mailman.171.1447073105.16136.python-list@python.org>
Message-ID: <0679c4f1-0e38-4b46-9224-59c95ff6bb44@googlegroups.com>

Thank you very much Chris



From artyprog at gmail.com  Mon Nov  9 10:13:59 2015
From: artyprog at gmail.com (Salvatore DI DIO)
Date: Mon, 9 Nov 2015 07:13:59 -0800 (PST)
Subject: Calulation in lim (1 + 1 /n) ^n when n -> infinite
In-Reply-To: <mailman.172.1447073456.16136.python-list@python.org>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
 <mailman.172.1447073456.16136.python-list@python.org>
Message-ID: <2e5327a5-2aa4-4dde-ad37-1d1e97cd9944@googlegroups.com>

Thank you very much Oscar,I was considerind using Mapple :-)


From artyprog at gmail.com  Mon Nov  9 10:15:17 2015
From: artyprog at gmail.com (Salvatore DI DIO)
Date: Mon, 9 Nov 2015 07:15:17 -0800 (PST)
Subject: Calulation in lim (1 + 1 /n) ^n when n -> infinite
In-Reply-To: <mailman.172.1447073456.16136.python-list@python.org>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
 <mailman.172.1447073456.16136.python-list@python.org>
Message-ID: <616e255d-80cf-436a-859d-6f400f61183b@googlegroups.com>

Thank you very much Oscar, I was considering using Mapple :-)


From rosuav at gmail.com  Mon Nov  9 10:17:59 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 02:17:59 +1100
Subject: using binary in python
In-Reply-To: <87si4fgs5f.fsf@elektro.pacujo.net>
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
 <mailman.174.1447077141.16136.python-list@python.org>
 <87si4fgs5f.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrh+W3+QrndT8dHgbvxEaLGxNXA=aaq0S3cX+w5Z0qS_Q@mail.gmail.com>

On Tue, Nov 10, 2015 at 1:32 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Yes, and lists and dicts and ints and objects and all. No problem there.
>
> However, when filenames and sys.stdin deal with text, things are getting
> iffy.

So where do you mark the boundary between the human and the OS? If I
create a GUI, I should be able to put an entry field down that accepts
Unicode text. And if I make a web form and an HTTP server, a user
should be able to type Unicode text into an <input> field and send
that along. Either way, my program should get a Unicode string. Why
shouldn't I be able to do the same with input()? And why, if a user
enters a plausible file name, should that not be able to be opened as
a file?

At what point do you say "this is for humans, this is for machines"?
Isn't it Python's job to spare us that hassle?

ChrisA


From rosuav at gmail.com  Mon Nov  9 10:24:53 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 02:24:53 +1100
Subject: Using tuple as parameter to a function
In-Reply-To: <87egfz5i9x.fsf@Equus.decebal.nl>
References: <87io5b5m1b.fsf@Equus.decebal.nl>
 <mailman.175.1447077487.16136.python-list@python.org>
 <87egfz5i9x.fsf@Equus.decebal.nl>
Message-ID: <CAPTjJmqA=-fdvAa0Wg46TgV6__bq7i7xwwqVS3mhWeDUs3p10Q@mail.gmail.com>

On Tue, Nov 10, 2015 at 2:01 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
>     for no_of_threads, no_of_records in values:

Beautiful! Though I'd shorten the names to just "threads" and
"records"; saying "number of X" isn't usually necessary, plus, the
general principle of Huffman coding your names recommends using
something shorter for a short-lived iteration variable. But otherwise,
that's exactly what I'd be looking at - descriptive and clear.

ChrisA


From random832 at fastmail.com  Mon Nov  9 10:32:17 2015
From: random832 at fastmail.com (Random832)
Date: Mon, 09 Nov 2015 10:32:17 -0500
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <878u69zxww.fsf@elektro.pacujo.net>
 <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87egfzgpdq.fsf@fastmail.com>

Steven D'Aprano <steve at pearwood.info> writes:
> The compiler doesn't need to decide in advance whether or not the module
> attributes have been changed. It can decide that at runtime, just before
> actually looking up the attribute. In pseudo-code:
>
>     if attribute might have changed:
>         use the slow path just like today
>     else:
>         use the optimized fast path


if attribute might have changed:
   check if attribute really did change
   if it didn't:
      reset means of determining if it might have changed
      goto the optimized fast path
   else:
      use the slow path and/or maybe make a new fast path
else:
   use the optimized fast path

And what if your optimization depends on _two_ things that might change?
Do you create one really fast path and two sort of fast paths?



From Cecil at decebal.nl  Mon Nov  9 10:44:33 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 09 Nov 2015 16:44:33 +0100
Subject: Commit: postgres on cursor and sqlite on connection
Message-ID: <878u675g9q.fsf@Equus.decebal.nl>

I have written some code I like to use with several databases. At the
moment sqlite and postgres. It looks like with progres I can use:
  cursor.execute('COMMIT;')
but that with sqlite I need to use:
    conn.commit()

Is this true, or am I doing something wrong?

When I use
  cursor.execute('COMMIT;')
with sqlite, I get:
    sqlite3.OperationalError: cannot commit - no transaction is active
While
    conn.commit()
does what it should do.

Before I do my statements I use:
  cursor.execute(BEGIN TRANSACTION;')

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From marko at pacujo.net  Mon Nov  9 10:46:13 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 09 Nov 2015 17:46:13 +0200
Subject: using binary in python
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
 <mailman.174.1447077141.16136.python-list@python.org>
 <87si4fgs5f.fsf@elektro.pacujo.net>
 <mailman.179.1447082283.16136.python-list@python.org>
Message-ID: <87lha7goqi.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Nov 10, 2015 at 1:32 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Yes, and lists and dicts and ints and objects and all. No problem
>> there.
>>
>> However, when filenames and sys.stdin deal with text, things are
>> getting iffy.
>
> So where do you mark the boundary between the human and the OS? If I
> create a GUI, I should be able to put an entry field down that accepts
> Unicode text. And if I make a web form and an HTTP server, a user
> should be able to type Unicode text into an <input> field and send
> that along. Either way, my program should get a Unicode string. Why
> shouldn't I be able to do the same with input()? And why, if a user
> enters a plausible file name, should that not be able to be opened as
> a file?

sys.stdin is not (primarily) a human interface. It is the canonical
channel to relay the input data to the program. The results of the
computation are emitted through sys.stdout.

The input data could well be, say, UTF-8-encoded plain text, or a PDF
file, or a Zip file, or a music recording.

As for file names, even UTF-8 Linux environments often contain filenames
that are illegal UTF-8. Using surrogate characters is a clever trick,
but might even lead to security risks when more than one pathname can
map to the same surrogate encoding.

> At what point do you say "this is for humans, this is for machines"?
> Isn't it Python's job to spare us that hassle?

Python is certainly trying to do that.

   Flik: I was just trying to help.
   Mr. Soil: Then help us; *don't* help us. 

   <URL: http://www.imdb.com/title/tt0120623/quotes>


I program for Linux. I use different programming languages, but the
target is Linux. The systems I build and deal with consist of different
components written in different programming languages but they all
follow Linux-y conventions to work harmoniously together. I don't in any
way benefit from a smoke screen a programming language offers to place
in front of the operating system.


Marko


From rosuav at gmail.com  Mon Nov  9 10:57:01 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 02:57:01 +1100
Subject: using binary in python
In-Reply-To: <87lha7goqi.fsf@elektro.pacujo.net>
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
 <mailman.174.1447077141.16136.python-list@python.org>
 <87si4fgs5f.fsf@elektro.pacujo.net>
 <mailman.179.1447082283.16136.python-list@python.org>
 <87lha7goqi.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqC=B63zhg9cKrDLAAoPpSCaP6yzOiG=YF7NkJjz13AnA@mail.gmail.com>

On Tue, Nov 10, 2015 at 2:46 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> I program for Linux. I use different programming languages, but the
> target is Linux. The systems I build and deal with consist of different
> components written in different programming languages but they all
> follow Linux-y conventions to work harmoniously together. I don't in any
> way benefit from a smoke screen a programming language offers to place
> in front of the operating system.

Then, as I said before: You do not want Python. Go use something else
that lets you get closer to the OS - possibly C, but possibly not. I'm
going to keep using a language that lets me write for humans, because
they are my target. Not Linux. People.

ChrisA


From zljubisic at gmail.com  Mon Nov  9 11:12:12 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 08:12:12 -0800 (PST)
Subject: Getting response by email reply message
Message-ID: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>

Hi,

I know how to send an email, but I would like to be able to receive a reply and act accordingly.
Mail reply should contain yes/no answer.

I don't know whether email is appropriate for such function.
Maybe better idea would be to have links in email body, one for yes, another for no that will execute something on the server.

Anyway, what are my options?

Regards.


From marko at pacujo.net  Mon Nov  9 11:17:13 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 09 Nov 2015 18:17:13 +0200
Subject: using binary in python
References: <20151108212706.GA29701@z-sverige.nu>
 <mailman.168.1447065689.16136.python-list@python.org>
 <87d1vjigqf.fsf@elektro.pacujo.net>
 <mailman.169.1447067069.16136.python-list@python.org>
 <8737wfi9ss.fsf@elektro.pacujo.net>
 <mailman.174.1447077141.16136.python-list@python.org>
 <87si4fgs5f.fsf@elektro.pacujo.net>
 <mailman.179.1447082283.16136.python-list@python.org>
 <87lha7goqi.fsf@elektro.pacujo.net>
 <mailman.182.1447084624.16136.python-list@python.org>
Message-ID: <87h9kvgnau.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Tue, Nov 10, 2015 at 2:46 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> I program for Linux. I use different programming languages, but the
>> target is Linux. The systems I build and deal with consist of
>> different components written in different programming languages but
>> they all follow Linux-y conventions to work harmoniously together. I
>> don't in any way benefit from a smoke screen a programming language
>> offers to place in front of the operating system.
>
> Then, as I said before: You do not want Python. Go use something else
> that lets you get closer to the OS

Python still offers almost all of the system programming facilities.
Python3 is slowly drifting away, but it's still all there, thankfully.


Marko


From joel.goldstick at gmail.com  Mon Nov  9 11:21:06 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Mon, 9 Nov 2015 11:21:06 -0500
Subject: Getting response by email reply message
In-Reply-To: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
Message-ID: <CAPM-O+x3ZDBMAD16JWu9PYB-7KN1AjhKQms9LFTHOm_VmtvmCw@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:12 AM, <zljubisic at gmail.com> wrote:

> Hi,
>
> I know how to send an email, but I would like to be able to receive a
> reply and act accordingly.
> Mail reply should contain yes/no answer.
>
> I don't know whether email is appropriate for such function.
> Maybe better idea would be to have links in email body, one for yes,
> another for no that will execute something on the server.
>
> Anyway, what are my options?
>
> Regards.
> --
> https://mail.python.org/mailman/listinfo/python-list
>

I'm assuming this is a website.  If so, why not use a form with a checkbox?

-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From bc at freeuk.com  Mon Nov  9 11:54:21 2015
From: bc at freeuk.com (BartC)
Date: Mon, 9 Nov 2015 16:54:21 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <mailman.160.1447031104.16136.python-list@python.org>
References: <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net>
 <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
Message-ID: <n1qivn$o17$1@dont-email.me>

On 09/11/2015 01:04, Ben Finney wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>
>> Hmm, then I was misunderstanding what BartC was advocating. I didn't
>> think it would *fail* in the presence of dynamic attributes, but
>> merely *perform suboptimally* (and presumably worse than current
>> CPython).
>
> There isn't a way for the compiler to *know*, in all cases, whether
> module attributes will be updated during the lifetime of the program

In what way can an attribute be updated, other than deleting it altogether?

(Moving or renaming can be done in terms of creation and deletion. For 
the purposes of trying to avoid a lookup, we're not that interested in 
much else.)

-- 
Bart C.




From ian.g.kelly at gmail.com  Mon Nov  9 12:46:24 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 9 Nov 2015 10:46:24 -0700
Subject: Commit: postgres on cursor and sqlite on connection
In-Reply-To: <878u675g9q.fsf@Equus.decebal.nl>
References: <878u675g9q.fsf@Equus.decebal.nl>
Message-ID: <CALwzidk0d2mj_DuO=GBim+U5OZhkH65Mxrn6CtB17cgWV849uQ@mail.gmail.com>

On Mon, Nov 9, 2015 at 8:44 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> I have written some code I like to use with several databases. At the
> moment sqlite and postgres. It looks like with progres I can use:
>   cursor.execute('COMMIT;')
> but that with sqlite I need to use:
>     conn.commit()
>
> Is this true, or am I doing something wrong?
>
> When I use
>   cursor.execute('COMMIT;')
> with sqlite, I get:
>     sqlite3.OperationalError: cannot commit - no transaction is active
> While
>     conn.commit()
> does what it should do.
>
> Before I do my statements I use:
>   cursor.execute(BEGIN TRANSACTION;')

This looks like it answers your question:

http://stackoverflow.com/questions/9773200/python-sqlite3-cannot-commit-no-transaction-is-active


From pkpearson at nowhere.invalid  Mon Nov  9 12:51:34 2015
From: pkpearson at nowhere.invalid (Peter Pearson)
Date: 9 Nov 2015 17:51:34 GMT
Subject: Calulation in  lim  (1  + 1 /n) ^n  when  n -> infinite
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
Message-ID: <dac4p6Fq56qU1@mid.individual.net>

On Mon, 9 Nov 2015 04:21:14 -0800 (PST), Salvatore DI DIO wrote:
>
> I was trying to show that this limit was 'e'
> But when I try large numbers I get errors
>
> def lim(p):
>     return math.pow(1 + 1.0 / p , p)
>
>>>> lim(500000000)
> 2.718281748862504
>>>> lim(900000000)
> 2.7182820518605446  !!!!

Python floats have close to 16 decimal digits of precision.  When you
compute 1+1/p with large p, the result will be close to 1, so digits of
1/p beyond the 16th place will be damaged by rounding.  For p of
900000000, the first nearly-9 digits of 1/p are zero, so the first
"significant" digit is the 10th, and beyond the 16th digit -- the 7th
significant digit -- they're damaged, so you can only expect about 
16-9 = 7 significant digits to be accurate.  And as it turns out,
2.7182820518605446 is good to about 7 significant figures.

It takes longer to explain than to see: roundoff limits you to ...

   (digits of p) + (good digits in the result) = 16  (approximately)

-- 
To email me, substitute nowhere->runbox, invalid->com.


From Cecil at decebal.nl  Mon Nov  9 12:54:26 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 09 Nov 2015 18:54:26 +0100
Subject: Using tuple as parameter to a function
References: <87io5b5m1b.fsf@Equus.decebal.nl>
 <mailman.175.1447077487.16136.python-list@python.org>
 <87egfz5i9x.fsf@Equus.decebal.nl>
 <mailman.180.1447082701.16136.python-list@python.org>
Message-ID: <874mgv5a99.fsf@Equus.decebal.nl>

On Monday  9 Nov 2015 16:24 CET, Chris Angelico wrote:

> On Tue, Nov 10, 2015 at 2:01 AM, Cecil Westerhof <Cecil at decebal.nl> wrote:
>> for no_of_threads, no_of_records in values:
>
> Beautiful! Though I'd shorten the names to just "threads" and
> "records"; saying "number of X" isn't usually necessary, plus, the
> general principle of Huffman coding your names recommends using
> something shorter for a short-lived iteration variable.

Done.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From python.list at tim.thechases.com  Mon Nov  9 13:15:29 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 9 Nov 2015 12:15:29 -0600
Subject: Getting response by email reply message
In-Reply-To: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
Message-ID: <20151109121529.2a3e7c03@bigbox.christie.dr>

On 2015-11-09 08:12, zljubisic at gmail.com wrote:
> I know how to send an email, but I would like to be able to receive
> a reply and act accordingly. Mail reply should contain yes/no
> answer.

You have a couple options that occur to me:

1) set up an SMTP server somewhere (or use the existing one you're
receiving this email at in the event you're getting it as mail
rather than reading it via NNTP or a web interface) to receive the
mail, then create a Python script to poll that inbox (usually POP3 or
IMAP) for messages addressed.  The mails can be extracted, parsed,
and deleted

2) similar to above, set up an SMTP server, but use server processing
scripts (e.g. procmail scripts) to launch some script when matching
emails are received.  It would save you from polling (reducing server
load) and most scripting frameworks pipe the message in on stdin so
you don't have to muck with POP3/IMAP logins.

3) write your own STMP daemon that would do listen and react when
appropriate messages come in.

In most cases, I'd expect that #2 is the easiest/best solution. The
biggest exception being if you have a mail server that doesn't play
well with external tools that expect stdin/stdout processing
(coughexchangecough).

-tkc





From ben+python at benfinney.id.au  Mon Nov  9 14:45:40 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 06:45:40 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <878u69zxww.fsf@elektro.pacujo.net>
 <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <85fv0fgdnf.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> The compiler doesn't need to decide in advance whether or not the
> module attributes have been changed. It can decide that at runtime,
> just before actually looking up the attribute. In pseudo-code:
>
>     if attribute might have changed:
>         use the slow path just like today
>     else:
>         use the optimized fast path

As you have pointed out earlier, the ?attribute might have changed?
condition is set by *any* non-trivial code ? notably, a function
call, though that doesn't exhaust the ways of setting that condition.

So the remaining space of code that is safe for the proposed
optimisation is trivially small. Why bother with such optimisations, if
the only code that can benefit is *already* small and simple?

I'm not asking you (Steven) to defend the proposal, I'm pointing out
that the ?problem? being addressed is essentially the dynamism of
Python. The proposal is misguided.

-- 
 \         ?Truth would quickly cease to become stranger than fiction, |
  `\                     once we got as used to it.? ?Henry L. Mencken |
_o__)                                                                  |
Ben Finney



From ben+python at benfinney.id.au  Mon Nov  9 14:52:07 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 06:52:07 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <878u69zxww.fsf@elektro.pacujo.net>
 <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <n1qivn$o17$1@dont-email.me>
Message-ID: <85bnb3gdco.fsf@benfinney.id.au>

BartC <bc at freeuk.com> writes:

> On 09/11/2015 01:04, Ben Finney wrote:
> > There isn't a way for the compiler to *know*, in all cases, whether
> > module attributes will be updated during the lifetime of the program
>
> In what way can an attribute be updated, other than deleting it
> altogether?

* Bind a new name to a value.
* Re-bind an existing name to a different value.
* Delete an existing name.

Any of those can be done at run-time, in any module's namespace, by
arbitrary code somewhere in the program.

-- 
 \        ?Sane people have an appropriate perspective on the relative |
  `\     importance of foodstuffs and human beings. Crazy people can't |
_o__)                 tell the difference.? ?Paul Z. Myers, 2010-04-18 |
Ben Finney



From lac at openend.se  Mon Nov  9 15:07:56 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 09 Nov 2015 21:07:56 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <85fv0fgdnf.fsf@benfinney.id.au>
References: <n1kshk$brb$1@dont-email.me> <878u69zxww.fsf@elektro.pacujo.net>
 <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <85fv0fgdnf.fsf@benfinney.id.au>
Message-ID: <201511092007.tA9K7vbW000701@fido.openend.se>

In a message of Tue, 10 Nov 2015 06:45:40 +1100, Ben Finney writes:
>So the remaining space of code that is safe for the proposed
>optimisation is trivially small. Why bother with such optimisations, if
>the only code that can benefit is *already* small and simple?

You have things backwards.
The reason that you want to optimise this is that it is small, simple, 
and slow_slow_slow_slow_slow.

It is the things that are complicated and large that usually aren't worth
optimising. You don't call them often enough for it to be worth it to
optimise them.  Your analysis and set up overhead will be more than
the speed gains you realise.  If you can find something that is small,
simple, and ubiquitous -- that's the place to look for performance
gains.

PyPy gets most of its speed by optimising loops.  Most loops in Python
run perfectly well without making use of any of the dynanism that is
potentially available -- "it's nice to have the ability to do something
that, as a matter of fact, I am not going to do right now".  But the
overhead for checking to see if I have made use of it is huge, which
is why 'set things up so that if it is never used, we can go pretty much
as fast as C' is a win.  After you have paid for your setup costs for
making the fast and the slow path, you get enough fast path activity
that you come out way ahead.

Laura






From zljubisic at gmail.com  Mon Nov  9 16:36:47 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 13:36:47 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <a9201732-4c33-41bf-9da4-f9dd395bd522@googlegroups.com>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <a9201732-4c33-41bf-9da4-f9dd395bd522@googlegroups.com>
Message-ID: <db59d562-0419-492e-b620-62b31b1f3d1c@googlegroups.com>

Hi, 

You are right. I am trying to address a few questions at the same time.
As English is not my first language, I can only say that you have addressed them very well. Thanks. 
1. Where to put the try/except block, inside or outside the function 
2. How to deal with un-anticipated exceptions 
3. How to keep record 

1.	If try/except block is outside the function, I have to always put function call in try/except block, even for logging. From my point of view, I could put at least logging in the function and then re raise the error. 
2.	I have just read what TDD is. I should write my first unit test to get a grip. Anyway, I have a program in which I am looping through several of records. If something happens I would like to put the warning in the log. In that case I need to put for loop in try/except Exception as e: block in order to log an unknown exception 
3.	For me, logging is necessary. Every script (only few of them) I have done, has a underlying log.

Thanks.

Regards.


From zljubisic at gmail.com  Mon Nov  9 16:43:42 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 13:43:42 -0800 (PST)
Subject: How to handle exceptions properly in a pythonic way?
In-Reply-To: <mailman.44.1446699105.16136.python-list@python.org>
References: <4b303213-62e2-42d4-b2f6-4fc1f6025944@googlegroups.com>
 <n18fmg$oj6$1@reader1.panix.com>
 <e134f1a3-89cc-4497-807e-3dd0836fb5e6@googlegroups.com>
 <mailman.43.1446695916.16136.python-list@python.org>
 <4cb51da8-9331-4efe-87d3-dfe9c2ae0f8e@googlegroups.com>
 <mailman.44.1446699105.16136.python-list@python.org>
Message-ID: <70b30688-2558-4974-bdb8-e579f4ffa6fa@googlegroups.com>

Hi,

> def get_html(...):
>     try:
>         ... actually go get the info
>         return info
>     except (ConnectionError, OSError, SocketError) as e:
>         raise ContentNotFoundError from e

Personally, I never liked "early returns". I would rather used a variable and the last line in the function would be return variable.
Anyway, I got the point.

> To use this code, what you'd do is:
> 
> try:
>     data = get_html(...)
> except ContentNotFoundError:
>     # deal with the case of not having anything to work with

I got a picture. Thanks.

I have to rethink now about two approaches. One would be as you have suggested in this mail - raising ContentNotFoundError, and another one would be not to mask root exceptions and deal with them instead of ContentNotFoundError.

You have clarified to me the concept. Thanks.

Regards. 


From zljubisic at gmail.com  Mon Nov  9 16:45:32 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 13:45:32 -0800 (PST)
Subject: Getting response by email reply message
In-Reply-To: <mailman.183.1447086069.16136.python-list@python.org>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.183.1447086069.16136.python-list@python.org>
Message-ID: <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>

> I'm assuming this is a website.  If so, why not use a form with a checkbox?

One of ideas is to put two url's in the email, one for yes and the other one for no.

I am also thinking about reading/parsing the reply mail.

Regards.


From zljubisic at gmail.com  Mon Nov  9 16:53:24 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 13:53:24 -0800 (PST)
Subject: Getting response by email reply message
In-Reply-To: <mailman.185.1447093595.16136.python-list@python.org>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.185.1447093595.16136.python-list@python.org>
Message-ID: <fccaef52-59bd-4165-a570-2abb6a229dbc@googlegroups.com>

> You have a couple options that occur to me:
> 
> 1) set up an SMTP server somewhere (or use the existing one you're
> receiving this email at in the event you're getting it as mail
> rather than reading it via NNTP or a web interface) to receive the
> mail, then create a Python script to poll that inbox (usually POP3 or
> IMAP) for messages addressed.  The mails can be extracted, parsed,
> and deleted

Why should I setup the SMTP server? If my email is on gmail server, I can read the messages from there from time to time.

> 2) similar to above, set up an SMTP server, but use server processing
> scripts (e.g. procmail scripts) to launch some script when matching
> emails are received.  It would save you from polling (reducing server
> load) and most scripting frameworks pipe the message in on stdin so
> you don't have to muck with POP3/IMAP logins.

That would be nice but I don't have an access to the server processing scripts.

> 3) write your own STMP daemon that would do listen and react when
> appropriate messages come in.

For now, I could set some time interval, let's say every five minutes for mail checking. I could parse the mail, but at the moment I am not sure how mail body should look like in order to be sure that I have parsed the information correctly.

I agree, #2 is the best approach because you are doing something when the mail arrives. In this case you don't have to pull mail server from time to time.

Regards.


From denismfmcmahon at gmail.com  Mon Nov  9 17:14:54 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Mon, 9 Nov 2015 22:14:54 -0000 (UTC)
Subject: Getting response by email reply message
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.185.1447093595.16136.python-list@python.org>
 <fccaef52-59bd-4165-a570-2abb6a229dbc@googlegroups.com>
Message-ID: <n1r5su$qit$3@dont-email.me>

On Mon, 09 Nov 2015 13:53:24 -0800, zljubisic wrote:

>> You have a couple options that occur to me:
>> 
>> 1) set up an SMTP server somewhere (or use the existing one you're
>> receiving this email at in the event you're getting it as mail rather
>> than reading it via NNTP or a web interface) to receive the mail, then
>> create a Python script to poll that inbox (usually POP3 or IMAP) for
>> messages addressed.  The mails can be extracted, parsed, and deleted
> 
> Why should I setup the SMTP server? If my email is on gmail server, I
> can read the messages from there from time to time.

Read more carefully!

The earlier poster suggested options that would work if you set up your 
own server, or already had one.

You can poll your gmail server using pop3 as the earlier reply suggested.

You may need to configure some options in your gmail account to allow 
pop3 access.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From ian.g.kelly at gmail.com  Mon Nov  9 17:30:51 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 9 Nov 2015 15:30:51 -0700
Subject: Getting response by email reply message
In-Reply-To: <20151109121529.2a3e7c03@bigbox.christie.dr>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <20151109121529.2a3e7c03@bigbox.christie.dr>
Message-ID: <CALwzidkv-OavOTPYMPGL=LRRo_O13ULCyNQqeDBCtkTYCoYgCQ@mail.gmail.com>

On Mon, Nov 9, 2015 at 11:15 AM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2015-11-09 08:12, zljubisic at gmail.com wrote:
>> I know how to send an email, but I would like to be able to receive
>> a reply and act accordingly. Mail reply should contain yes/no
>> answer.
>
> You have a couple options that occur to me:
>
> 1) set up an SMTP server somewhere (or use the existing one you're
> receiving this email at in the event you're getting it as mail
> rather than reading it via NNTP or a web interface) to receive the
> mail, then create a Python script to poll that inbox (usually POP3 or
> IMAP) for messages addressed.  The mails can be extracted, parsed,
> and deleted
>
> 2) similar to above, set up an SMTP server, but use server processing
> scripts (e.g. procmail scripts) to launch some script when matching
> emails are received.  It would save you from polling (reducing server
> load) and most scripting frameworks pipe the message in on stdin so
> you don't have to muck with POP3/IMAP logins.
>
> 3) write your own STMP daemon that would do listen and react when
> appropriate messages come in.
>
> In most cases, I'd expect that #2 is the easiest/best solution. The
> biggest exception being if you have a mail server that doesn't play
> well with external tools that expect stdin/stdout processing
> (coughexchangecough).

I'd agree with that provided that the SMTP server is already set up
somewhere and you're able to to just add a procmail script to it.

I wouldn't suggest trying to set up an SMTP server without a strong
reason, however. These things are surprisingly tricky to configure so
that your server doesn't get used for spam forwarding, and if you
don't play nicely with the SMTP community then you'll find your domain
and mail server getting added to various blacklists.

If you don't already have an SMTP server to use, better IMO to just
use hosted email like Gmail or Zoho. The need to poll it may be an
inconvenience, but you'll likely avoid some headaches in the long run.


From rosuav at gmail.com  Mon Nov  9 17:37:40 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 09:37:40 +1100
Subject: Getting response by email reply message
In-Reply-To: <CALwzidkv-OavOTPYMPGL=LRRo_O13ULCyNQqeDBCtkTYCoYgCQ@mail.gmail.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <20151109121529.2a3e7c03@bigbox.christie.dr>
 <CALwzidkv-OavOTPYMPGL=LRRo_O13ULCyNQqeDBCtkTYCoYgCQ@mail.gmail.com>
Message-ID: <CAPTjJmrhrKe6hcRwAcPHGX-OyLSQijDGt2oVUwdhcgj2ZDoGhA@mail.gmail.com>

On Tue, Nov 10, 2015 at 9:30 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> I wouldn't suggest trying to set up an SMTP server without a strong
> reason, however. These things are surprisingly tricky to configure so
> that your server doesn't get used for spam forwarding, and if you
> don't play nicely with the SMTP community then you'll find your domain
> and mail server getting added to various blacklists.

Easiest way to prevent it from forwarding spam is to make it
incoming-only. But yes, you do need to know a bit about how the
internet works; if all you want to do is poll for mail every X
minutes, a POP3 or IMAP connection is far simpler.

ChrisA


From marko at pacujo.net  Mon Nov  9 17:43:57 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 10 Nov 2015 00:43:57 +0200
Subject: Getting response by email reply message
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <20151109121529.2a3e7c03@bigbox.christie.dr>
 <mailman.189.1447108292.16136.python-list@python.org>
Message-ID: <87k2pqvln6.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> I wouldn't suggest trying to set up an SMTP server without a strong
> reason, however. These things are surprisingly tricky to configure so
> that your server doesn't get used for spam forwarding, and if you
> don't play nicely with the SMTP community then you'll find your domain
> and mail server getting added to various blacklists.

That's the reason I ended up writing my own SMTP server (in Python3): I
just never could figure out how to configure Postfix to my liking.

For once I appreciated the tons of spam arriving at my mail address. I
didn't have to come up with test material because every few minutes a
fresh spam message came knocking on my door.


Marko


From python.list at tim.thechases.com  Mon Nov  9 17:45:20 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Mon, 9 Nov 2015 16:45:20 -0600
Subject: Getting response by email reply message
In-Reply-To: <fccaef52-59bd-4165-a570-2abb6a229dbc@googlegroups.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.185.1447093595.16136.python-list@python.org>
 <fccaef52-59bd-4165-a570-2abb6a229dbc@googlegroups.com>
Message-ID: <20151109164520.2d0b1615@bigbox.christie.dr>

On 2015-11-09 13:53, zljubisic at gmail.com wrote:
> > You have a couple options that occur to me:
> > 
> > 1) set up an SMTP server somewhere (or use the existing one you're
> > receiving this email at in the event you're getting it as mail
> > rather than reading it via NNTP or a web interface) to receive the
> > mail, then create a Python script to poll that inbox (usually
> > POP3 or IMAP) for messages addressed.  The mails can be
> > extracted, parsed, and deleted
> 
> Why should I setup the SMTP server? If my email is on gmail server,
> I can read the messages from there from time to time.

Thus my suggestion "or use the existing one you're receiving this
email at")

Once you have an SMTP+IMAP server like Gmail, you can use
"imaplib" (or "poplib") from the stdlib to log into your Gmail
account, pull down the messages (I presume you identify them somehow,
either by tag, sorting them into a given folder, or something in the
Subject line), and process the message body.

> For now, I could set some time interval, let's say every five
> minutes for mail checking. I could parse the mail, but at the
> moment I am not sure how mail body should look like in order to be
> sure that I have parsed the information correctly.

With imaplib/poplib, you get email.message items back.  You
can .walk() through the mime-tree extracting each part and then
searching it for whatever expression you need to determine whether
the vote was a Yes or No.

Check out the docs on
https://docs.python.org/2/library/email.message.html

-tkc





From ben+python at benfinney.id.au  Mon Nov  9 18:21:05 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 10:21:05 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <85fv0fgdnf.fsf@benfinney.id.au>
 <201511092007.tA9K7vbW000701@fido.openend.se>
Message-ID: <85d1vig3oe.fsf@benfinney.id.au>

Laura Creighton <lac at openend.se> writes:

> In a message of Tue, 10 Nov 2015 06:45:40 +1100, Ben Finney writes:
> >So the remaining space of code that is safe for the proposed
> >optimisation is trivially small. Why bother with such optimisations, if
> >the only code that can benefit is *already* small and simple?
>
> You have things backwards.
> The reason that you want to optimise this is that it is small, simple, 
> and slow_slow_slow_slow_slow.
>
> It is the things that are complicated and large that usually aren't
> worth optimising. You don't call them often enough for it to be worth
> it to optimise them.

I appreciate you making the the distinction explicit between a small and
simple *code unit* (e.g. an small, simple, often-called function),
versus a large and complex *code unit* (e.g. a large, complex,
infrequently-called class definition).

I'm pointing out an orthogonal issue: The only code to which the
proposed optimisation could apply is *module-level* (infrequently
called) code, which *has no complications* (i.e. not a code unit).

The simplicitly of the small section of code is not the issue; the
dynamism of the entire program is what negates the applicability of the
optimisation.

If the simple, predictable-by-the-compiler segment of code were actually
isolated in a simple unit, then yes, such optimisations might be
considered. But, as already discussed, the optimisation is not intended
to apply to such code units. So that is moot in this case.

Instead, we're talking about optimisations proposed *only* for
module-level code (i.e. not isolated); and what negates their
applicability is *any* dynamism (i.e. not simple), anywhere in the
program (i.e. not a code unit). The space of applicability for the
proposed optimisation shrinks to irrelevance, AFAICT.

-- 
 \        ?If the arguments in favor of atheism upset you, explain why |
  `\        they?re wrong. If you can?t do that, that?s your problem.? |
_o__)                                     ?Amanda Marcotte, 2015-02-13 |
Ben Finney



From ben+python at benfinney.id.au  Mon Nov  9 18:29:59 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 10:29:59 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me> <857flujwy7.fsf@benfinney.id.au>
 <5640B28C.6050408@rece.vub.ac.be>
Message-ID: <858u66g39k.fsf@benfinney.id.au>

Antoon Pardon <antoon.pardon at rece.vub.ac.be> writes:

> Op 07-11-15 om 04:43 schreef Ben Finney:
> > Python assumes the programmers using it are consenting adults. Doing
> > harmful things is difficult but not forbidden.
>
> I find that to be contradictory. Why should you make something difficult
> if you are consenting adults?

It's no more contradictory than the fact Python makes it difficult for
consenting adults to exchange hard-to-follow code indentation. The
principle that There Should Be (Preferably Only) One Obvious Way To Do
It directly implies that other ways should be difficult. That's not a
contradiction with treating Python programmers as consenting adults.

> This whole idea of python assuming we are consenting adults and thus
> making it impossible to not consent seems weird.

You misunderstand the implication: I'm saying that because Python
assumes we are consenting adults, that such actions remain possible.

> > Notably, the author of a library should not be forbidding the Pythonic
> > ability to change name bindings as needed.
>
> If the author of a library doesn't wish to consent to this I don't see
> what is wrong with that.

Who is doing what to whom? The user of the library isn't doing anything
to the library author, so what is it the library author would consent
to? Instead, you seem to be trying to assert a *power* of the library
author to restrict the library user. Such a power is not granted by
Python.

Instead, the library author is obliged to treat the library user as an
adult who consents to the freedoms inherent to Python's design, and to
not restrict their use of the library needlessly.

-- 
 \     ?Facts are stubborn things; and whatever may be our wishes, our |
  `\   inclinations, or the dictates of our passion, they cannot alter |
_o__)        the state of facts and evidence.? ?John Adams, 1770-12-04 |
Ben Finney



From bjlazlo at gmail.com  Mon Nov  9 18:52:45 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Mon, 9 Nov 2015 15:52:45 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using Python
 2.7.10
Message-ID: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>

This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
========================
The student scores need to be summed.
========================
import json
import urllib
url = "http://www.wickson.net/geography_assignment.json"
response = urllib.urlopen(url)
data = json.loads(response.read())
lst1 = list(data.items())
print lst1


From python at mrabarnett.plus.com  Mon Nov  9 19:29:50 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 10 Nov 2015 00:29:50 +0000
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
Message-ID: <56413A7E.9090102@mrabarnett.plus.com>

On 2015-11-09 23:52, Bernie Lazlo wrote:
> This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
> ========================
> The student scores need to be summed.
> ========================
> import json
> import urllib
> url = "http://www.wickson.net/geography_assignment.json"
> response = urllib.urlopen(url)
> data = json.loads(response.read())
> lst1 = list(data.items())
> print lst1
>
Do it a step at a time.

It's a list, so start with indexing.


From makamisato at yahoo.com  Mon Nov  9 19:34:23 2015
From: makamisato at yahoo.com (M. Kamisato)
Date: Tue, 10 Nov 2015 00:34:23 +0000 (UTC)
Subject: Python.exe is not a valid Win32 application error message
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
Message-ID: <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>

I am running python on Windows XP SP3 and download version 3.5xx. ?I got the above error message and could not run the program.
I have downloaded Python version 2.7xx and it runs fine.
Is there any way I can get version 3.5xx to run on my computer?
Mel KamisatoBuena Park, CA

From makamisato at yahoo.com  Mon Nov  9 19:34:23 2015
From: makamisato at yahoo.com (M. Kamisato)
Date: Tue, 10 Nov 2015 00:34:23 +0000 (UTC)
Subject: Python.exe is not a valid Win32 application error message
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
Message-ID: <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>

I am running python on Windows XP SP3 and download version 3.5xx. ?I got the above error message and could not run the program.
I have downloaded Python version 2.7xx and it runs fine.
Is there any way I can get version 3.5xx to run on my computer?
Mel KamisatoBuena Park, CA

From bjlazlo at gmail.com  Mon Nov  9 20:12:35 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Mon, 9 Nov 2015 17:12:35 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <mailman.194.1447115400.16136.python-list@python.org>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <mailman.194.1447115400.16136.python-list@python.org>
Message-ID: <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>

On Monday, 9 November 2015 19:30:23 UTC-5, MRAB  wrote:
> On 2015-11-09 23:52, Bernie Lazlo wrote:
> > This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
> > ========================
> > The student scores need to be summed.
> > ========================
> > import json
> > import urllib
> > url = "http://www.wickson.net/geography_assignment.json"
> > response = urllib.urlopen(url)
> > data = json.loads(response.read())
> > lst1 = list(data.items())
> > print lst1
> >
> Do it a step at a time.
> 
> It's a list, so start with indexing.

MRAB:

I think of the file as two lists. The second list appears to be a list of tuples containing "names" and "scores". How would you index or extract those.


From python at mrabarnett.plus.com  Mon Nov  9 20:31:23 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 10 Nov 2015 01:31:23 +0000
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <mailman.194.1447115400.16136.python-list@python.org>
 <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
Message-ID: <564148EB.7060507@mrabarnett.plus.com>

On 2015-11-10 01:12, Bernie Lazlo wrote:
> On Monday, 9 November 2015 19:30:23 UTC-5, MRAB  wrote:
>> On 2015-11-09 23:52, Bernie Lazlo wrote:
>> > This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
>> > ========================
>> > The student scores need to be summed.
>> > ========================
>> > import json
>> > import urllib
>> > url = "http://www.wickson.net/geography_assignment.json"
>> > response = urllib.urlopen(url)
>> > data = json.loads(response.read())
>> > lst1 = list(data.items())
>> > print lst1
>> >
>> Do it a step at a time.
>>
>> It's a list, so start with indexing.
>
> MRAB:
>
> I think of the file as two lists. The second list appears to be a list of tuples containing "names" and "scores". How would you index or extract those.
>
Right, so lst1[1] gets you closer to what you want.

Further indexing will get you even closer.



From bjlazlo at gmail.com  Mon Nov  9 20:53:27 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Mon, 9 Nov 2015 17:53:27 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <mailman.195.1447119088.16136.python-list@python.org>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <mailman.194.1447115400.16136.python-list@python.org>
 <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
 <mailman.195.1447119088.16136.python-list@python.org>
Message-ID: <f8caed74-3069-4f49-b30c-4080a7199656@googlegroups.com>

On Monday, 9 November 2015 20:31:52 UTC-5, MRAB  wrote:
> On 2015-11-10 01:12, Bernie Lazlo wrote:
> > On Monday, 9 November 2015 19:30:23 UTC-5, MRAB  wrote:
> >> On 2015-11-09 23:52, Bernie Lazlo wrote:
> >> > This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
> >> > ========================
> >> > The student scores need to be summed.
> >> > ========================
> >> > import json
> >> > import urllib
> >> > url = "http://www.wickson.net/geography_assignment.json"
> >> > response = urllib.urlopen(url)
> >> > data = json.loads(response.read())
> >> > lst1 = list(data.items())
> >> > print lst1
> >> >
> >> Do it a step at a time.
> >>
> >> It's a list, so start with indexing.
> >
> > MRAB:
> >
> > I think of the file as two lists. The second list appears to be a list of tuples containing "names" and "scores". How would you index or extract those.
> >
> Right, so lst1[1] gets you closer to what you want.
> 
> Further indexing will get you even closer.
===========
lst2 = lst1[1] removes first line of  instructions

printing lst2[1:2] produces essentially the list of students and scores ??

([{u'student ': u'Hannah', u'score': 77}, {u'student ': u'Emily', u'score': 57}, {u'student ': u'Olivia', u'score': 80}, {u'student ': u'Nora', u'score': 70},


From python at mrabarnett.plus.com  Mon Nov  9 21:13:00 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 10 Nov 2015 02:13:00 +0000
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <f8caed74-3069-4f49-b30c-4080a7199656@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <mailman.194.1447115400.16136.python-list@python.org>
 <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
 <mailman.195.1447119088.16136.python-list@python.org>
 <f8caed74-3069-4f49-b30c-4080a7199656@googlegroups.com>
Message-ID: <564152AC.8010905@mrabarnett.plus.com>

On 2015-11-10 01:53, Bernie Lazlo wrote:
> On Monday, 9 November 2015 20:31:52 UTC-5, MRAB  wrote:
>> On 2015-11-10 01:12, Bernie Lazlo wrote:
>> > On Monday, 9 November 2015 19:30:23 UTC-5, MRAB  wrote:
>> >> On 2015-11-09 23:52, Bernie Lazlo wrote:
>> >> > This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
>> >> > ========================
>> >> > The student scores need to be summed.
>> >> > ========================
>> >> > import json
>> >> > import urllib
>> >> > url = "http://www.wickson.net/geography_assignment.json"
>> >> > response = urllib.urlopen(url)
>> >> > data = json.loads(response.read())
>> >> > lst1 = list(data.items())
>> >> > print lst1
>> >> >
>> >> Do it a step at a time.
>> >>
>> >> It's a list, so start with indexing.
>> >
>> > MRAB:
>> >
>> > I think of the file as two lists. The second list appears to be a list of tuples containing "names" and "scores". How would you index or extract those.
>> >
>> Right, so lst1[1] gets you closer to what you want.
>>
>> Further indexing will get you even closer.
> ===========
> lst2 = lst1[1] removes first line of  instructions
>
> printing lst2[1:2] produces essentially the list of students and scores ??
>
> ([{u'student ': u'Hannah', u'score': 77}, {u'student ': u'Emily', u'score': 57}, {u'student ': u'Olivia', u'score': 80}, {u'student ': u'Nora', u'score': 70},
>
lst1 is 1 list of 2 items, both of which are tuples. lst1[1] gives you
the second tuple.

That tuple contains 2 items, the first a string and the second a list.
You want the second item, so that's lst1[1][1].

Each of the items in that list is a dict.



From hpiwowar at gmail.com  Mon Nov  9 21:36:13 2015
From: hpiwowar at gmail.com (Heather Piwowar)
Date: Mon, 9 Nov 2015 18:36:13 -0800 (PST)
Subject: find which Python libraries are most influential in scientific
 research
Message-ID: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>

Today's scientists often turn to Python to run analysis, simulation, and other sciency tasks.

That makes us wonder: which Python libraries are most influential in scientific research? 

We just released a tool (built in Python, of course) to answer that question. It's called Depsy [1], it's funded by the US National Science Foundation, and we'd love your comments.

For more information, see our blog post [2] and paper [3].  The scientific/engineering tag is a great place to start exploring [4].

Heather Piwowar and Jason Priem

1. http://depsy.org
2. http://blog.impactstory.org/introducing-depsy 
3. https://github.com/Impactstory/depsy-research/blob/master/introducing_depsy.md
4. http://depsy.org/tag/scientific%252Fengineering


From steve at pearwood.info  Mon Nov  9 21:37:38 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 10 Nov 2015 13:37:38 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <878u69zxww.fsf@elektro.pacujo.net>
 <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
Message-ID: <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Tue, 10 Nov 2015 06:45 am, Ben Finney wrote:

> Steven D'Aprano <steve at pearwood.info> writes:
> 
>> The compiler doesn't need to decide in advance whether or not the
>> module attributes have been changed. It can decide that at runtime,
>> just before actually looking up the attribute. In pseudo-code:
>>
>>     if attribute might have changed:
>>         use the slow path just like today
>>     else:
>>         use the optimized fast path
> 
> As you have pointed out earlier, the ?attribute might have changed?
> condition is set by *any* non-trivial code ? notably, a function
> call, though that doesn't exhaust the ways of setting that condition.

Ben, I fear that you are not paying attention to me :-)

The compiler doesn't need to decide *in advance* whether the attribute might
have changed. It knows whether it has changed or not *at runtime*.

I'm not a compiler writer, but I pretend to be one on Usenet *wink* so don't
take this as gospel. Treat it as a simple-minded illustration of what sort
of thing a JIT compiler could do.

It's one thing to say that *in principle* any function might modify or
shadow builtins. That's true, because we don't know what's inside the
function. But the compiler knows, because it actually executes the code
inside the function and can see what happens when it does. It doesn't have
to predict in advance whether or not calling `func(x)` shadows the builtin
`len` function, *it can see for itself* whether it did or not.

At compile time, `func(x)` might do anything. But at runtime, we know
exactly what it did, because it just did it.

Imagine that the compiler keeps track of whether or not builtins has been
modified. Think of it as a simple "dirty" flag that says "yes, builtins is
still pristine" or "no, something may have shadowed or modified the
builtins". That's fairly straight-forward: builtins is a dict, and the
compiler can tell whether or not __setitem__ etc has been called on that
dict. Likewise, it can keep track of whether or not a global has been
created that shadows builtins: some of that can be done statically, at
compile-time, but most of it needs to be done dynamically, at runtime.

If the flag is set, the compiler knows that the optimization is unsafe and
it has to follow the standard name lookup, and you lose nothing: the
standard Python semantics are still followed. But if the flag is clear, the
compiler knows that nothing has shadowed or modified builtins, and a whole
class of optimizations are safe. It can replace a call to (say) len(x) with
a fast jump, avoiding an unnecessary name lookup in globals, and another
unnecessary name lookup in builtins. Or it might even inline the call to
len. Since *most* code doesn't play tricks with builtins, the overhead of
tracking these changes pays off *most* of the time -- and when it doesn't,
the penalty is very small.

Depending on how smart the compiler is, there are all sorts of things it can
do. The state of the art (not bleeding edge) for JIT compilers is pretty
smart these days. CPython is a simple-minded, dumb compiler, and that's the
way Guido likes it (its the reference implementation, not the fastest or
most memory efficient implementation). But PyPy can approach the speed of
statically optimized C, at least sometimes, and certainly can beat CPython
by an order of magnitude. Likewise Javascript's V8 compiler.

> So the remaining space of code that is safe for the proposed
> optimisation is trivially small. Why bother with such optimisations, if
> the only code that can benefit is *already* small and simple?

That is absolutely not correct.


-- 
Steven



From contact at stridebird.com  Mon Nov  9 21:38:15 2015
From: contact at stridebird.com (Pete Dowdell)
Date: Tue, 10 Nov 2015 09:38:15 +0700
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <mailman.194.1447115400.16136.python-list@python.org>
 <a5ad1e84-cd46-44b7-a7d4-ed0f9b74ec92@googlegroups.com>
Message-ID: <56415897.5030502@stridebird.com>

On 10/11/15 08:12, Bernie Lazlo wrote:
> > > import json
> > >import urllib
> > >url ="http://www.wickson.net/geography_assignment.json"
> > >response = urllib.urlopen(url)
> > >data = json.loads(response.read())

All good up to data. Now:
# make a list of scores
scores = [d['score'] for d in data['comments']  if 
isinstance(d['score'], int) ]
# analysis
total_scores = sum(scores)
average_score= total_scores/float(len(scores))
min_score, max_score = min(scores), max(scores)

pd


From bjlazlo at gmail.com  Mon Nov  9 22:21:10 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Mon, 9 Nov 2015 19:21:10 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
Message-ID: <e34d03e9-7e80-4bbb-8910-d01ad4e9c950@googlegroups.com>

On Monday, 9 November 2015 18:53:06 UTC-5, Bernie Lazlo  wrote:
> This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
> ========================
> The student scores need to be summed.
> ========================
> import json
> import urllib
> url = "http://www.wickson.net/geography_assignment.json"
> response = urllib.urlopen(url)
> data = json.loads(response.read())
> lst1 = list(data.items())
> print lst1
==========================

Many thanks, MRAB!  :-)


From denismfmcmahon at gmail.com  Mon Nov  9 22:25:09 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Tue, 10 Nov 2015 03:25:09 -0000 (UTC)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
Message-ID: <n1ro2l$n3t$1@dont-email.me>

On Mon, 09 Nov 2015 15:52:45 -0800, Bernie Lazlo wrote:

> This should be a simple problem but I have wasted hours on it. Any help
> would be appreciated. [I have taken my code back to almost the very
> beginning.]
> ========================
> The student scores need to be summed.
> ========================
> import json import urllib url =
> "http://www.wickson.net/geography_assignment.json"
> response = urllib.urlopen(url)
> data = json.loads(response.read())
> lst1 = list(data.items())
> print lst1

I find that pprint.pprint is useful for looking at data structures.

Having looked at the data, and then using appropriate substitutions for 
<something> and <keyval> in the following:

sumscore = 0
students = 0

for dic in <something>:
    sumscore = sumscore + dic[<keyval>]
    students += 1

print 'Sum of', students, 'scores is', sumscore
print 'Average of', students, 'scores is', sumscore / students

It was trivial to generate:

Sum of 50 scores is 3028
Average of 50 scores is 60

-- 
Denis McMahon, denismfmcmahon at gmail.com


From wayne.wickson at gmail.com  Mon Nov  9 22:53:38 2015
From: wayne.wickson at gmail.com (wayne.wickson at gmail.com)
Date: Mon, 9 Nov 2015 19:53:38 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <n1ro2l$n3t$1@dont-email.me>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <n1ro2l$n3t$1@dont-email.me>
Message-ID: <9a9e1664-7b36-473d-bebf-3de7c7d13b94@googlegroups.com>

On Monday, 9 November 2015 22:27:40 UTC-5, Denis McMahon  wrote:
> On Mon, 09 Nov 2015 15:52:45 -0800, Bernie Lazlo wrote:
> 
> > This should be a simple problem but I have wasted hours on it. Any help
> > would be appreciated. [I have taken my code back to almost the very
> > beginning.]
> > ========================
> > The student scores need to be summed.
> > ========================
> > import json import urllib url =
> > "http://www.wickson.net/geography_assignment.json"
> > response = urllib.urlopen(url)
> > data = json.loads(response.read())
> > lst1 = list(data.items())
> > print lst1
> 
> I find that pprint.pprint is useful for looking at data structures.
> 
> Having looked at the data, and then using appropriate substitutions for 
> <something> and <keyval> in the following:
> 
> sumscore = 0
> students = 0
> 
> for dic in <something>:
>     sumscore = sumscore + dic[<keyval>]
>     students += 1
> 
> print 'Sum of', students, 'scores is', sumscore
> print 'Average of', students, 'scores is', sumscore / students
> 
> It was trivial to generate:
> 
> Sum of 50 scores is 3028
> Average of 50 scores is 60
> 
> -- 
> Denis McMahon
=========================================
Thanks for the reply, Denis. I hope this comes as easily to me some day. :-)



From lac at openend.se  Tue Nov 10 00:42:04 2015
From: lac at openend.se (Laura Creighton)
Date: Tue, 10 Nov 2015 06:42:04 +0100
Subject: Getting response by email reply message
In-Reply-To: <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.183.1447086069.16136.python-list@python.org>
 <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>
Message-ID: <201511100542.tAA5g4ii011082@fido.openend.se>

In a message of Mon, 09 Nov 2015 13:45:32 -0800, zljubisic at gmail.com writes:
>> I'm assuming this is a website.  If so, why not use a form with a checkbox?
>
>One of ideas is to put two url's in the email, one for yes and the other one for no.
>
>I am also thinking about reading/parsing the reply mail.
>
>Regards.

If what you really need is a voting application, you can look at
https://github.com/mdipierro/evote  which the PSF uses for its elections.

Laura


From ben+python at benfinney.id.au  Tue Nov 10 01:10:09 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 17:10:09 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <854mgufkqm.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> Ben, I fear that you are not paying attention to me :-)

Possibly, though I also think there's miscommunication in this thread.

You speak of ?compile time? and ?run time?. You also speak of what the
compiler can do, at run time.

I am a Bear of Little Brain, but: Isn't anything that the *compiler*
does, by definition done at *compile* time?

The run-time behaviour of the program is, of course, *affected* by what
the compiler has done in the past. But the compiler acts only at compile
time, and its compile-time behaviour can't be determined by what's
happening at run time.

If that's not true, I fear we're not talking about the same things.

> At compile time, `func(x)` might do anything. But at runtime, we know
> exactly what it did, because it just did it.

Sure. All my statements about compile-time optimisations are those that
can be applied at compile time (which I intend to be synonymous with
?when the compiler is doing its job?), and so can't be informed by what
happens at run time.

If the proposal is to make optimisations that must be informed by the
run-time state of the running program, we're surely talking about not
just the compiler any more. No?

-- 
 \          ?Any sufficiently advanced bug is indistinguishable from a |
  `\                                          feature.? ?Rich Kulawiec |
_o__)                                                                  |
Ben Finney



From orgnut at yahoo.com  Tue Nov 10 01:20:25 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Mon, 9 Nov 2015 22:20:25 -0800
Subject: using binary in python
In-Reply-To: <mailman.164.1447060794.16136.python-list@python.org>
References: <mailman.164.1447060794.16136.python-list@python.org>
Message-ID: <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>

Your questions are somewhat difficult to answer because you misunderstand binary.  The key is 
that EVERYTHING in a computer is binary.  There are NO EXCEPTIONS, it's all binary ALL the time. 
  The difference comes about in how this binary data is displayed and manipulated.  I want to 
emphasize, ALL the DATA is binary.

On 11/08/2015 01:27 PM, kent nyberg wrote:
> Hi there,
> Lets say I want to play around with binary files in python.
> Opening and using files in python is something that I think I've sort of got the hang of.
> The thing im wondering about is binary files.
> While searching for binary and python I started reading about bin().
> I can use bin() to convert integers to binary.

No.  It doesn't convert anything.  It takes the integer data (which is internally binary) and 
gives you a _string_ representing that value in a binary format.  The same with hex() and oct() 
which give _strings_ of text corresponding to those formats.  The original integer data is 
unchanged -- and is still internally binary data.

> Now, I thought..  some way it should be possible to write "binary" files.
> That is, non ascii-files.  For example, on Linux, if I run the command 'less' on a binary;
> for example /bin/ls, then the command asks me if I really want to do it, since its a binary file.
> I know why, since the non ascii-stuff messes up the terminal, and most likely since you rarely want to
> look at a binary file with less.

Not so much that it's rare, it's just that the less (and similar) commands expect the _binary 
data_ that it is given represents text encoded in ascii, utf-8, whatever...  And ls is a 
executable program not text.  So less (or the like) tries to display that data as text, and of 
course, the result is garbage.  (GIGO)

If you really want to look at a non-text file this way, there are utilities to do this properly, 
like hexdump.

> Well, lets assume I want to write and read binary.  How is it done?
> The built in bin() function only converts integers to binary but the variable or return is still just letters right?
> Converting the integer '1' to binary with bin() return 0b1. Which is ok. Its the binary representation of integer 1.
> But since.. there is files which contains data that is not representable as ascii, then I assume it can be written.
> But can it by Python?

Of course it can.  The only difference a text file and a binary file is the way it's opened. 
Text files are opened with 'r' or 'w', while binary files are opened with 'rb' or 'wb'.  Being 
different modes, the reading/writing is handled differently.  One obvious difference, the lines 
of a text file are marked by ending them with a newline character, so it's easy to read/write 
the text line-by-line.  But the data in a binary file is completely arbitrary and is much 
trickier to handle (is an individual piece of data 1 byte, two bytes, 12,428 bytes or...)  Once 
again I'll emphasize that the _data_ in a text file is binary, it's just that these binary data 
values represent text codes.  The data in a binary file can represent anything, a program, a 
.jpg picture, .mp3 music, a company Personnel record, or anything else.

BTW, I talk about text codes as a generic term -- there are many choices of how text is encoded.

> Ok, I get the feeling now that its hard to understand my question. I assume in the C language its just matter of
> writing a complex struct with strange variables and just write it to a file. But in python..?

There is no essential difference between how C and Python handle binary files.  The principles 
are the same, only the details differ.  You can ignore comparing to C here.

> Can some one give a short explenation of a python write to file, that makes it a binary file?

A short explanation, probably not in a newsgroup post.  Try searching the web for Python binary 
files, or similar search terms.  Then sit down and play!  ;-)

> Thanks alot,  and forgive me for my stupid questions. :)
> /Kent Nyberg

It's not a stupid question, but is is based on your misunderstanding of binary.  Don't give up, 
you'll get it!  Just keep in mind that _ALL_ the underlying _DATA_ is binary, it is just how 
this data is displayed and manipulated that makes the differences.  And it is important that you 
understand the difference between the actual (binary) data and the way it is displayed -- these 
are two entirely different things.

Sorry that I'm not more specific on the 'how' to use binary files, but the subject is more 
complex than a simple explanation can properly give.

      -- Larry -=-



From dieter at handshake.de  Tue Nov 10 01:53:56 2015
From: dieter at handshake.de (dieter)
Date: Tue, 10 Nov 2015 07:53:56 +0100
Subject: Commit: postgres on cursor and sqlite on connection
References: <878u675g9q.fsf@Equus.decebal.nl>
Message-ID: <87h9ku1h17.fsf@handshake.de>

Cecil Westerhof <Cecil at decebal.nl> writes:

> I have written some code I like to use with several databases. At the
> moment sqlite and postgres. It looks like with progres I can use:
>   cursor.execute('COMMIT;')
> but that with sqlite I need to use:
>     conn.commit()
>
> Is this true, or am I doing something wrong?

There might be differences between various database interface libraries.
I am using "psycopg" to interface with Postgres - and which it,
you can also use "conn.commit" (as with "sqlite").




From zljubisic at gmail.com  Tue Nov 10 02:09:50 2015
From: zljubisic at gmail.com (zljubisic at gmail.com)
Date: Mon, 9 Nov 2015 23:09:50 -0800 (PST)
Subject: Getting response by email reply message
In-Reply-To: <mailman.197.1447134132.16136.python-list@python.org>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.183.1447086069.16136.python-list@python.org>
 <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>
 <mailman.197.1447134132.16136.python-list@python.org>
Message-ID: <82415229-a6b3-44ff-bae0-0e847dbd9d13@googlegroups.com>

> If what you really need is a voting application, you can look at
> https://github.com/mdipierro/evote  which the PSF uses for its elections.

It is not a voting application (I will have more than yes/no answers).
I just want to keep an example simple.

Anyway, I will look into voting application you have suggested in order to see the way how they do it. Thanks.

Regards.


From artyprog at gmail.com  Tue Nov 10 03:26:13 2015
From: artyprog at gmail.com (Salvatore DI DIO)
Date: Tue, 10 Nov 2015 00:26:13 -0800 (PST)
Subject: Calulation in  lim  (1  + 1 /n) ^n  when  n -> infinite
In-Reply-To: <dac4p6Fq56qU1@mid.individual.net>
References: <ea008366-9aa2-47e6-b4b7-69e5d447d408@googlegroups.com>
 <dac4p6Fq56qU1@mid.individual.net>
Message-ID: <11f5750f-9ffb-464c-b2d2-71baa7e26ba3@googlegroups.com>

Thank you very much Peter


From tjreedy at udel.edu  Tue Nov 10 03:30:05 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 10 Nov 2015 03:30:05 -0500
Subject: Question about math.pi is mutable
In-Reply-To: <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <n1kshk$brb$1@dont-email.me> <n1l3kd$5ma$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1s9uk$ss2$1@ger.gmane.org>

On 11/9/2015 9:37 PM, Steven D'Aprano wrote:

> The compiler doesn't need to decide *in advance* whether the attribute might
> have changed. It knows whether it has changed or not *at runtime*.

You are using 'compiler' when you should, to avoid confusion, use 
'interpreter'.

> It's one thing to say that *in principle* any function might modify or
> shadow builtins. That's true, because we don't know what's inside the
> function. But the compiler knows, because it actually executes the code

'interpreter'

> inside the function and can see what happens when it does. It doesn't have
> to predict in advance whether or not calling `func(x)` shadows the builtin
> `len` function, *it can see for itself* whether it did or not.
>
> At compile time, `func(x)` might do anything. But at runtime, we know
> exactly what it did, because it just did it.
>
> Imagine that the compiler keeps track of whether or not builtins has been

/compiler/code compiled by the compiler and interpreted by the 
interpreter (which could be the CPU)/

> modified. Think of it as a simple "dirty" flag that says "yes, builtins is
> still pristine" or "no, something may have shadowed or modified the
> builtins". That's fairly straight-forward: builtins is a dict, and the
> compiler can tell whether or not __setitem__ etc has been called on that
> dict. Likewise, it can keep track of whether or not a global has been
> created that shadows builtins: some of that can be done statically, at
> compile-time, but most of it needs to be done dynamically, at runtime.

This is more or less Victor Stinner's proposal, and he has a working 
prototype that runs nearly all the test suite.  He now plans to refine 
it and measure changes in space and time usage.

> If the flag is set, the compiler knows that the optimization is unsafe and
> it has to follow the standard name lookup, and you lose nothing: the
> standard Python semantics are still followed. But if the flag is clear, the
> compiler knows that nothing has shadowed or modified builtins, and a whole
> class of optimizations are safe. It can replace a call to (say) len(x) with
> a fast jump, avoiding an unnecessary name lookup in globals, and another
> unnecessary name lookup in builtins. Or it might even inline the call to
> len. Since *most* code doesn't play tricks with builtins, the overhead of
> tracking these changes pays off *most* of the time -- and when it doesn't,
> the penalty is very small.


-- 
Terry Jan Reedy



From antoon.pardon at rece.vub.ac.be  Tue Nov 10 05:03:24 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 10 Nov 2015 11:03:24 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <858u66g39k.fsf@benfinney.id.au>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me> <857flujwy7.fsf@benfinney.id.au>
 <5640B28C.6050408@rece.vub.ac.be> <858u66g39k.fsf@benfinney.id.au>
Message-ID: <5641C0EC.8010905@rece.vub.ac.be>

Op 10-11-15 om 00:29 schreef Ben Finney:
>
> Who is doing what to whom? The user of the library isn't doing anything
> to the library author, so what is it the library author would consent
> to? Instead, you seem to be trying to assert a *power* of the library
> author to restrict the library user. Such a power is not granted by
> Python.

Python is not at liberty to grant or deny such a power. Python is just
a vehicle in which code is written. The author of a library can restrict
its use anyway he sees fit.

> Instead, the library author is obliged to treat the library user as an
> adult who consents to the freedoms inherent to Python's design, and to
> not restrict their use of the library needlessly.

There is no such obligation. And if it was an obligation, you can hardly
talk about consenting. Consenting adults mean that either party can
decide on conditions. Once one party is obligated it is no longer consenting.

-- 
Antoon Pardon



From harirammanohar159 at gmail.com  Tue Nov 10 05:16:34 2015
From: harirammanohar159 at gmail.com (harirammanohar159 at gmail.com)
Date: Tue, 10 Nov 2015 02:16:34 -0800 (PST)
Subject: help in pexpect multiprocessing
In-Reply-To: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
References: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
Message-ID: <c6e1a6a5-e7fb-4692-a47e-1da04043b11e@googlegroups.com>

On Monday, 9 November 2015 18:07:36 UTC+5:30, hariramm... at gmail.com  wrote:
> Hi,
> 
> I am using multiprocessing with pexpect, issue is whenever i call a function which is having expect(), its throwing error which is genuine as multiple threads are processing it same time (i/o prompt same time by multiple processes..so issues in picture...), so i want to use lock for that section alone to avoid it, but still fails in implementing it...can you help me
> 
> username = input('Enter your username: ')
> password = getpass.getpass()
> 
> s = pxssh.pxssh()
> s.login ('host','username','password')
> s.sendline ('ps -ef|grep java')
> s.prompt(timeout=1)
> 
> Try 1:
> 
> if condition == 'met':
>        np = len(list1)
>        p = multiprocessing.Pool(np)
>        p.map(stop, [(ds) for ds in list1])
> 
> def stop(ds):
>         s.sendline ('cd /usr')
>         if condition:
>                 lock = threading.Lock()
>                 lock.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 lock.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Try 2:
> 
> if condition == 'met':
>         lock = Lock()
>         for ds in list1:
>                 Process(target=stop, args=(ds,lock)).start()
> 
> def stop(ds,l):
>         s.sendline ('cd /usr')
>         if condition:
>                 l.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 l.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Both are giving me same trace..
> 
> pexpect.ExceptionPexpect: isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process?
> 
> Thanks in Advance

Hi,

can any one check it out


From lac at openend.se  Tue Nov 10 05:23:21 2015
From: lac at openend.se (Laura Creighton)
Date: Tue, 10 Nov 2015 11:23:21 +0100
Subject: Getting response by email reply message
In-Reply-To: <82415229-a6b3-44ff-bae0-0e847dbd9d13@googlegroups.com>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.183.1447086069.16136.python-list@python.org>
 <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>
 <mailman.197.1447134132.16136.python-list@python.org>
 <82415229-a6b3-44ff-bae0-0e847dbd9d13@googlegroups.com>
Message-ID: <201511101023.tAAANLUH000336@fido.openend.se>

In a message of Mon, 09 Nov 2015 23:09:50 -0800, zljubisic at gmail.com writes:
>> If what you really need is a voting application, you can look at
>> https://github.com/mdipierro/evote  which the PSF uses for its elections.
>
>It is not a voting application (I will have more than yes/no answers).
>I just want to keep an example simple.
>
>Anyway, I will look into voting application you have suggested in order to see the way how they do it. Thanks.

Their is no demand for 'yes/no answers' -- you can typically vote for
7 people out of 15 candidates for the board, for instance.  But, once
you get to the website you can serve up webpages, using web2py which
presents the voters with a webpage full of whatever you want to render,
including text boxes that let you do arbitrary submissions.

The hard problem being solved here is that only a select list of people
(whom you reach through email) can vote, 
they can do so during some arbitrary period of time (your election period) 
but they do not have to all be on-line at the same time, 
everybody who is legally allowed to vote can change their minds about whom
to vote for and re-submit a vote again, invalidating the earlier one,
and anonymity -- even the election commissioner who holds the election 
does not know who it was that any voter voted for, only that they voted.

And it also keeps track of vote totals.  There are also things to enable
you to present the candidates in different orders for different sets
of voters, as the order in which a list is dished up seems to effect the
outcome, with implications for 'election fairness'.

Thus the whole app is about accountablity.  The tiny web page you serve
up to the people is a tiny bag you bolt into its side. :)  Which makes
the whole thing way, way, way to heavy-weight for most purposes.

However, if accountability is what you need, then it would probably
be easier to adapt the election app to do what you want then to
reinvent all this stuff.

Laura


From lac at openend.se  Tue Nov 10 05:33:34 2015
From: lac at openend.se (Laura Creighton)
Date: Tue, 10 Nov 2015 11:33:34 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <854mgufkqm.fsf@benfinney.id.au>
References: <n1kshk$brb$1@dont-email.me>
 <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com>
 <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <854mgufkqm.fsf@benfinney.id.au>
Message-ID: <201511101033.tAAAXYZP001340@fido.openend.se>

In a message of Tue, 10 Nov 2015 17:10:09 +1100, Ben Finney writes:
>Steven D'Aprano <steve at pearwood.info> writes:
>
>> Ben, I fear that you are not paying attention to me :-)
>
>Possibly, though I also think there's miscommunication in this thread.
>
>You speak of ?compile time? and ?run time?. You also speak of what the
>compiler can do, at run time.
>
>I am a Bear of Little Brain, but: Isn't anything that the *compiler*
>does, by definition done at *compile* time?

No.

We used to have a pretty strict defintion about what a compiler was, and
what an interpreter was.  You did the compile things at compile time,
and then you the the interpreter things at runtime.

No more.  We have Just in Time compilers.  They do their compiling
at run time.  Or perhaps 'there is no such thing as compile time
any more'.

Laura



From lac at openend.se  Tue Nov 10 05:37:12 2015
From: lac at openend.se (Laura Creighton)
Date: Tue, 10 Nov 2015 11:37:12 +0100
Subject: Getting response by email reply message
In-Reply-To: <201511101023.tAAANLUH000336@fido.openend.se>
References: <79f2c622-e626-43ae-bcec-f85d394ce575@googlegroups.com>
 <mailman.183.1447086069.16136.python-list@python.org>
 <83cc2194-ca24-4c44-b5a0-ee6e7b0a8077@googlegroups.com>
 <mailman.197.1447134132.16136.python-list@python.org>
 <82415229-a6b3-44ff-bae0-0e847dbd9d13@googlegroups.com>
 <201511101023.tAAANLUH000336@fido.openend.se>
Message-ID: <201511101037.tAAAbCCl001678@fido.openend.se>

In a message of Tue, 10 Nov 2015 11:23:21 +0100, Laura Creighton writes:
>Their is no demand for 'yes/no answers' -- you can typically vote for

s/Their/There/

...

>the whole thing way, way, way to heavy-weight for most purposes.

s/to/too/
also s/heavy-weight/heavyweight/ depending on where in the world you
live, out of scope for this correction.

Sorry about that.  I need more caffeine.

Laura


From trindadegoncalves at gmail.com  Tue Nov 10 05:46:40 2015
From: trindadegoncalves at gmail.com (trindadegoncalves at gmail.com)
Date: Tue, 10 Nov 2015 02:46:40 -0800 (PST)
Subject: IDLE quits unexpectedly when about to open or creat a new file
Message-ID: <b42f7021-ab37-46da-a71f-13414c114606@googlegroups.com>

Hello,

I need help to find out what's going on. I did some research, but I couldn't find anything to solve this problem:

- I open the IDLE program;
- I go to the 'File' menu;
- I select the 'New File' option
- IDLE quits.

I run the IDLE version 3.3.3 on Windows 8.1 Pro.
Should I install the most recent version?

Thanks!


From rosuav at gmail.com  Tue Nov 10 06:01:17 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 10 Nov 2015 22:01:17 +1100
Subject: IDLE quits unexpectedly when about to open or creat a new file
In-Reply-To: <b42f7021-ab37-46da-a71f-13414c114606@googlegroups.com>
References: <b42f7021-ab37-46da-a71f-13414c114606@googlegroups.com>
Message-ID: <CAPTjJmoh5p2Fgd=zDgjNOEMsfkkgjOv7bcu7=8XcLQ1M=xNt+Q@mail.gmail.com>

On Tue, Nov 10, 2015 at 9:46 PM,  <trindadegoncalves at gmail.com> wrote:
> I need help to find out what's going on. I did some research, but I couldn't find anything to solve this problem:
>
> - I open the IDLE program;
> - I go to the 'File' menu;
> - I select the 'New File' option
> - IDLE quits.
>
> I run the IDLE version 3.3.3 on Windows 8.1 Pro.
> Should I install the most recent version?
>

That sounds like a very interesting problem. Can you try running it
from the command line, please? I'm not sure how to open one up from
Win 8, but it should be in the Start menu somewhere, or possibly press
Windows+R and type "cmd". With that up, type this:

python -m idlelib.idle

That should open up the same IDLE window that you know and recognize.
Do the exact same thing that caused the unexpected termination, and
then you should go back to the command prompt - hopefully with some
sort of error message. Copy and paste that message (as text, please,
not an image) into an email; that information could be very helpful.

ChrisA


From steve at pearwood.info  Tue Nov 10 06:34:16 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 10 Nov 2015 22:34:16 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <n1n8mc$33l$1@dont-email.me>
 <87ziyowy83.fsf@elektro.pacujo.net> <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
Message-ID: <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>

On Tue, 10 Nov 2015 05:10 pm, Ben Finney wrote:

> Steven D'Aprano <steve at pearwood.info> writes:
> 
>> Ben, I fear that you are not paying attention to me :-)
> 
> Possibly, though I also think there's miscommunication in this thread.
> 
> You speak of ?compile time? and ?run time?. You also speak of what the
> compiler can do, at run time.
> 
> I am a Bear of Little Brain, but: Isn't anything that the *compiler*
> does, by definition done at *compile* time?

In a manner of speaking, yes, of course. But you've missed the critical
issue: when is compile time?

If you're like most people, you probably are thinking about an execution
model where the compiler analyses the source code statically, using nothing
but what can be seen in the source code, then hands over some sort of
compiled byte code to be run by an interpreter or machine code that is
executed by the CPU. The compiler and interpreter are completely distinct.

If so, you're stuck with an obsolete model of computation, like somebody
trying to understand modern chemistry based on the "planetary orbit" model
of the atom.

So when is compile time? Of course, in some languages (like C, or Pascal)
compilation occurs as a distinct stage before you can run the code. But
that's not necessarily true for all compilers. "Just In Time" compilers
operate while the program is running, compiling code just before it is
executed. The distinction between compiler and interpreter is gone, or at
least weakened.

Python -- yes, even CPython -- has a runtime compiler. When you import a
module, it is compiled (if needed) just before the import. Likewise, when
you call the `compile`, `eval` or `exec` built-ins, the compiler operates.

I'm not calling this a JIT compiler, because the simple-minded compilation
performed by `compile` etc doesn't use any run-time information. It just
statically compiles the code to byte-code.

But the fact that it happens *at runtime* is significant, because in
principle there is a lot more information available to the compiler, if it
were intelligent enough to make use of it. For example, suppose you execute
this Python snippet:

result = x + 2

At static compile time, looking just at the source, you may not know what
value x is, or even whether or not x actually exists, so you're forced to
go through the standard Python semantics to determine what the result is:

py> from dis import dis
py> dis("result = x + 1")
  1           0 LOAD_NAME                0 (x)
              3 LOAD_CONST               0 (1)
              6 BINARY_ADD
              7 STORE_NAME               1 (result)
             10 LOAD_CONST               1 (None)
             13 RETURN_VALUE


But a JIT compiler gets to compile code right before that line is due to
execute. By the time the JIT compiler gets to see that line of code, it can
already know whether or not name "x" exists, and if so, which namespace it
is in. It knows what value "x" has. The compiler can choose what byte code,
or even machine code, to generate, using information available just before
that code is needed.

Suppose it knows that "x" is bound to an float. Then it can cast the int 1
to the machine floating point double 1.0 and generate code that adds that
to a float. That's likely to be tens of times faster than the BINARY_ADD
op-code, which has to do a whole lot of type-checking, method calling, and
creating and disposing of objects to add the two values.

Only if "x" is unknown, or if it is some type that doesn't have a convenient
optimization, does the JIT compiler generate the standard (but unoptimized)
BINARY_ADD op-code.

Provided that, on average, the book-keeping needed by the JIT compiler is
outweighed by the gains, the whole process counts as a win.

Now, CPython doesn't include a JIT compiler. But PyPy does, and it is much
more sophisticated than anything I could explain. I'm not the only one:

https://glyph.twistedmatrix.com/2012/02/this-isnt-how-pypy-works-but-it-might.html

If you remember Psycho, that might help. Psycho (according to its creator)
isn't a "true" JIT compiler, but it's close enough. Psycho would generate
machine code -- actual low level code running in the CPU or FPU, not byte
code -- for certain Python operations, plus guard code that ensured the
machine code was only called when it was safe to do so. So this is long
proven technology.

More about JIT compilation on Wikipedia:

https://en.wikipedia.org/wiki/Just-in-time_compilation



-- 
Steven



From bjlazlo at gmail.com  Tue Nov 10 07:14:00 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Tue, 10 Nov 2015 04:14:00 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <9a9e1664-7b36-473d-bebf-3de7c7d13b94@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
 <n1ro2l$n3t$1@dont-email.me>
 <9a9e1664-7b36-473d-bebf-3de7c7d13b94@googlegroups.com>
Message-ID: <a3a0cf1d-1642-4dcd-93cd-760af13388ee@googlegroups.com>

On Monday, 9 November 2015 22:54:05 UTC-5, wayne.... at gmail.com  wrote:
> On Monday, 9 November 2015 22:27:40 UTC-5, Denis McMahon  wrote:
> > On Mon, 09 Nov 2015 15:52:45 -0800, Bernie Lazlo wrote:
> > 
> > > This should be a simple problem but I have wasted hours on it. Any help
> > > would be appreciated. [I have taken my code back to almost the very
> > > beginning.]
> > > ========================
> > > The student scores need to be summed.
> > > ========================
> > > import json import urllib url =
> > > "http://www.wickson.net/geography_assignment.json"
> > > response = urllib.urlopen(url)
> > > data = json.loads(response.read())
> > > lst1 = list(data.items())
> > > print lst1
> > 
> > I find that pprint.pprint is useful for looking at data structures.
> > 
> > Having looked at the data, and then using appropriate substitutions for 
> > <something> and <keyval> in the following:
> > 
> > sumscore = 0
> > students = 0
> > 
> > for dic in <something>:
> >     sumscore = sumscore + dic[<keyval>]
> >     students += 1
> > 
> > print 'Sum of', students, 'scores is', sumscore
> > print 'Average of', students, 'scores is', sumscore / students
> > 
> > It was trivial to generate:
> > 
> > Sum of 50 scores is 3028
> > Average of 50 scores is 60
> > 
> > -- 
> > Denis McMahon
> =========================================
Thanks for the reply, Denis. I hope this comes as easily to me some day. :-) 


From ben+python at benfinney.id.au  Tue Nov 10 07:14:19 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 10 Nov 2015 23:14:19 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <854mgufkqm.fsf@benfinney.id.au>
 <201511101033.tAAAXYZP001340@fido.openend.se>
Message-ID: <85ziymdpb8.fsf@benfinney.id.au>

Laura Creighton <lac at openend.se> writes:

> In a message of Tue, 10 Nov 2015 17:10:09 +1100, Ben Finney writes:
> >I am a Bear of Little Brain, but: Isn't anything that the *compiler*
> >does, by definition done at *compile* time?
>
> No.
>
> We used to have a pretty strict defintion about what a compiler was,
> and what an interpreter was. You did the compile things at compile
> time, and then you the the interpreter things at runtime.
>
> No more. We have Just in Time compilers. They do their compiling at
> run time. Or perhaps 'there is no such thing as compile time any
> more'.

Very well. I argued on the basis of what could be determined at the time
Steven refers to as ?compile time?, i.e. before any part of the module
begins to run.


Steven D'Aprano <steve at pearwood.info> writes:

> Python -- yes, even CPython -- has a runtime compiler. When you import
> a module, it is compiled (if needed) just before the import. Likewise,
> when you call the `compile`, `eval` or `exec` built-ins, the compiler
> operates.
>
> I'm not calling this a JIT compiler, because the simple-minded
> compilation performed by `compile` etc doesn't use any run-time
> information. It just statically compiles the code to byte-code.

That's what I though. I'm aware of JIT compilers, and was pretty sure
Python doesn't have them. What's more, if it operates at a whole-module
level, and not later than when the module is imported.

Under those conditions, I maintain my objection to the proposed
optimisation.

The proposal is explicitly for optimisations made by the Python
compiler. As proposed, it only seems to be worthwhile once Python no
longer has a distinct ?compiler? and ?interpreter? is dissolved. Until
then, it seems pointless.

-- 
 \     ?There is something wonderful in seeing a wrong-headed majority |
  `\           assailed by truth.? ?John Kenneth Galbraith, 1989-07-28 |
_o__)                                                                  |
Ben Finney



From bjlazlo at gmail.com  Tue Nov 10 07:16:46 2015
From: bjlazlo at gmail.com (Bernie Lazlo)
Date: Tue, 10 Nov 2015 04:16:46 -0800 (PST)
Subject: Extracting and summing student scores from a JSON file using
 Python 2.7.10
In-Reply-To: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
References: <1d1610e5-d401-48f2-b5ee-3af91b9e485f@googlegroups.com>
Message-ID: <2c0e7cc9-c675-4f65-9aea-bf4c7ee13e64@googlegroups.com>

On Monday, 9 November 2015 18:53:06 UTC-5, Bernie Lazlo  wrote:
> This should be a simple problem but I have wasted hours on it. Any help would be appreciated. [I have taken my code back to almost the very beginning.]
> ========================
> The student scores need to be summed.
> ========================
> import json
> import urllib
> url = "http://www.wickson.net/geography_assignment.json"
> response = urllib.urlopen(url)
> data = json.loads(response.read())
> lst1 = list(data.items())
> print lst1

Pete, thanks for the input. Sometimes it just takes a suggestion to break past the "brick wall".


From harirammanohar159 at gmail.com  Tue Nov 10 07:22:49 2015
From: harirammanohar159 at gmail.com (harirammanohar159 at gmail.com)
Date: Tue, 10 Nov 2015 04:22:49 -0800 (PST)
Subject: help in pexpect multiprocessing
In-Reply-To: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
References: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
Message-ID: <b92b602e-2a46-4c44-837f-9b7a97e7c28c@googlegroups.com>

On Monday, 9 November 2015 18:07:36 UTC+5:30, hariramm... at gmail.com  wrote:
> Hi,
> 
> I am using multiprocessing with pexpect, issue is whenever i call a function which is having expect(), its throwing error which is genuine as multiple threads are processing it same time (i/o prompt same time by multiple processes..so issues in picture...), so i want to use lock for that section alone to avoid it, but still fails in implementing it...can you help me
> 
> username = input('Enter your username: ')
> password = getpass.getpass()
> 
> s = pxssh.pxssh()
> s.login ('host','username','password')
> s.sendline ('ps -ef|grep java')
> s.prompt(timeout=1)
> 
> Try 1:
> 
> if condition == 'met':
>        np = len(list1)
>        p = multiprocessing.Pool(np)
>        p.map(stop, [(ds) for ds in list1])
> 
> def stop(ds):
>         s.sendline ('cd /usr')
>         if condition:
>                 lock = threading.Lock()
>                 lock.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 lock.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Try 2:
> 
> if condition == 'met':
>         lock = Lock()
>         for ds in list1:
>                 Process(target=stop, args=(ds,lock)).start()
> 
> def stop(ds,l):
>         s.sendline ('cd /usr')
>         if condition:
>                 l.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 l.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Both are giving me same trace..
> 
> pexpect.ExceptionPexpect: isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process?
> 
> Thanks in Advance

Hi,

I am able to manage it by using process queues, thank you


From plucena24 at gmail.com  Tue Nov 10 07:42:02 2015
From: plucena24 at gmail.com (Pablo Lucena)
Date: Tue, 10 Nov 2015 07:42:02 -0500
Subject: help in pexpect multiprocessing
In-Reply-To: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
References: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
Message-ID: <CAB_tDZzoZz6TdKyuRJMWPx3TJcHgxtsD+5Whzgi2FVFKPSarpA@mail.gmail.com>

I think the problem is that you cannot pass around an open socket via
pickle. Whats the error message you are getting?

Try adding the session establishment code to the stop function, so that
each new process opens a session to the server and executes the command.

def stop(ds):
        s = pxssh.pxssh()
?    ?
s.login ('host','username','password')
        s.sendline ('ps -ef|grep java')
        s.prompt(timeout=1)
        s.sendline ('cd /usr')
        if condition:
                lock = threading.Lock()
                lock.acquire()
                s.expect('Enter username:')
                s.sendline ('user')
                s.expect('Enter password:*')
                s.sendline('pass')
                lock.release()
        s.prompt(timeout=200)
        print('stopped ds...')


if condition == 'met':
       np = len(list1)
       p = multiprocessing.Pool(np)
       p.map(stop, [(ds) for ds in list1])

On Mon, Nov 9, 2015 at 7:37 AM, <harirammanohar159 at gmail.com> wrote:

> Hi,
>
> I am using multiprocessing with pexpect, issue is whenever i call a
> function which is having expect(), its throwing error which is genuine as
> multiple threads are processing it same time (i/o prompt same time by
> multiple processes..so issues in picture...), so i want to use lock for
> that section alone to avoid it, but still fails in implementing it...can
> you help me
>
> username = input('Enter your username: ')
> password = getpass.getpass()
>
> s = pxssh.pxssh()
> s.login ('host','username','password')
> s.sendline ('ps -ef|grep java')
> s.prompt(timeout=1)
>
> Try 1:
>
> if condition == 'met':
>        np = len(list1)
>        p = multiprocessing.Pool(np)
>        p.map(stop, [(ds) for ds in list1])
>
> def stop(ds):
>         s.sendline ('cd /usr')
>         if condition:
>                 lock = threading.Lock()
>                 lock.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 lock.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
>
> Try 2:
>
> if condition == 'met':
>         lock = Lock()
>         for ds in list1:
>                 Process(target=stop, args=(ds,lock)).start()
>
> def stop(ds,l):
>         s.sendline ('cd /usr')
>         if condition:
>                 l.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 l.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
>
> Both are giving me same trace..
>
> pexpect.ExceptionPexpect: isalive() encountered condition where
> "terminated" is 0, but there was no child process. Did someone else call
> waitpid() on our process?
>
> Thanks in Advance
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
*Pablo Lucena*


From framstag at rus.uni-stuttgart.de  Tue Nov 10 08:08:18 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Tue, 10 Nov 2015 13:08:18 +0000 (UTC)
Subject: corrupt download with urllib2
Message-ID: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>

I am currently developing a program which should run on Linux and Windows.
Later it shall be compiled with PyInstaller. Therefore I am using Python 2.7

My program must download http://fex.belwue.de/download/7za.exe

I am using this code:

    sz = path.join(fexhome,'7za.exe')
    szurl = "http://fex.belwue.de/download/7za.exe"

   try:
      szo = open(sz,'w')
    except (IOError,OSError) as e:
      die('cannot write %s - %s' % (sz,e.strerror))
    import urllib2
    printf("\ndownloading %s\n",szurl)
    try:
      req = urllib2.Request(szurl)
      req.add_header('User-Agent',useragent)
      u = urllib2.urlopen(req)
    except urllib2.URLError as e:
      die('cannot get %s - %s' % (szurl,e.reason))
    except urllib2.HTTPError as e:
      die('cannot get %s - server reply: %d %s' % (szurl,e.code,e.reason))
    if u.getcode() == 200:
      print(u.read(),file=szo,end='')
      szo.close()
    else:
      die('cannot get %s - server reply: %d' % (szurl,u.getcode()))

It works with Linux, but not with Windows 7, where the downloaded 7za.exe is
corrupt: it has the wrong size, 589044 instead of 587776 Bytes.

Where is my error?


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From __peter__ at web.de  Tue Nov 10 08:20:29 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 10 Nov 2015 14:20:29 +0100
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n1squu$hcu$1@ger.gmane.org>

Ulli Horlacher wrote:

> I am currently developing a program which should run on Linux and Windows.
> Later it shall be compiled with PyInstaller. Therefore I am using Python
> 2.7
> 
> My program must download http://fex.belwue.de/download/7za.exe
> 
> I am using this code:

> It works with Linux, but not with Windows 7, where the downloaded 7za.exe
> is corrupt: it has the wrong size, 589044 instead of 587776 Bytes.
> 
> Where is my error?

>     sz = path.join(fexhome,'7za.exe')
>     szurl = "http://fex.belwue.de/download/7za.exe"
> 
>    try:
>       szo = open(sz,'w')

Open the file in binary mode to avoid the translation of "\n" into "\r\n":

        szo = open(sz, 'wb')

>     except (IOError,OSError) as e:
>       die('cannot write %s - %s' % (sz,e.strerror))

Unrelated, but I recommend that you let the exceptions bubble up for easier 
debugging.

Python is not Perl ;)

>     import urllib2
>     printf("\ndownloading %s\n",szurl)
>     try:
>       req = urllib2.Request(szurl)
>       req.add_header('User-Agent',useragent)
>       u = urllib2.urlopen(req)
>     except urllib2.URLError as e:
>       die('cannot get %s - %s' % (szurl,e.reason))
>     except urllib2.HTTPError as e:
>       die('cannot get %s - server reply: %d %s' % (szurl,e.code,e.reason))
>     if u.getcode() == 200:
>       print(u.read(),file=szo,end='')
>       szo.close()
>     else:
>       die('cannot get %s - server reply: %d' % (szurl,u.getcode()))
> 




From bc at freeuk.com  Tue Nov 10 08:26:53 2015
From: bc at freeuk.com (BartC)
Date: Tue, 10 Nov 2015 13:26:53 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
References: <n1kshk$brb$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
 <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n1sr6n$d6f$1@dont-email.me>

On 10/11/2015 11:34, Steven D'Aprano wrote:
> On Tue, 10 Nov 2015 05:10 pm, Ben Finney wrote:
>

>> I am a Bear of Little Brain, but: Isn't anything that the *compiler*
>> does, by definition done at *compile* time?
>
> In a manner of speaking, yes, of course. But you've missed the critical
> issue: when is compile time?
>
> If you're like most people, you probably are thinking about an execution
> model where the compiler analyses the source code statically, using nothing
> but what can be seen in the source code, then hands over some sort of
> compiled byte code to be run by an interpreter or machine code that is
> executed by the CPU. The compiler and interpreter are completely distinct.

Does the Python language specify how it is to be compiled and executed?

If not, then you can use any interpretation you like, provided the 
program gives the expected results.

That includes using a static compilation pass that generates byte-code, 
even if it is only done immediately before running the main module, or 
just before performing an import operation on another.

> If so, you're stuck with an obsolete model of computation, like somebody
> trying to understand modern chemistry based on the "planetary orbit" model
> of the atom.
>
> So when is compile time? Of course, in some languages (like C, or Pascal)
> compilation occurs as a distinct stage before you can run the code. But
> that's not necessarily true for all compilers.

C can also be interpreted from source as you go along, although it can 
be very difficult (but probably not as difficult as implementing PyPy).

Anything is possible. But the chances are that if you are running 
CPython, then it will probably include a discrete byte-code compiler.

> execute
> this Python snippet:
>
> result = x + 2
>
> At static compile time, looking just at the source, you may not know what
> value x is, or even whether or not x actually exists, so you're forced to
> go through the standard Python semantics to determine what the result is:
>
> py> from dis import dis
> py> dis("result = x + 1")
>    1           0 LOAD_NAME                0 (x)
>                3 LOAD_CONST               0 (1)
>                6 BINARY_ADD
>                7 STORE_NAME               1 (result)
>               10 LOAD_CONST               1 (None)
>               13 RETURN_VALUE
>
>
> But a JIT compiler gets to compile code right before that line is due to
> execute. By the time the JIT compiler gets to see that line of code, it can
> already know whether or not name "x" exists, and if so, which namespace it
> is in. It knows what value "x" has.

How does it do that? How is the 'x+1' even stored in the machine? 
Suppose the preceding lines are:

    if random+bit()==1:
       x=920.5
    else:
       x=[8,5,4,9,1,7,6,3,2]

or:

    if some_condition: del x

it will probably know as much about x as the static compiler does! And a 
static compiler can still do a surprising bit of analysis, such as 
transforming the the first if-statement above, followed by your return 
statement, into:

    if random_bit()==1:
       return 922.5
    else:
       raise_error()

But we're trying to find ways of avoiding a dictionary lookup, ie a 
LOAD_GLOBAL or LOAD_NAME. If static analysis of the entire source can 
yield fixed tables of such names as 'x', even if subject to runtime 
alterations, then why not do that if it means possible faster access.

> More about JIT compilation on Wikipedia:
>
> https://en.wikipedia.org/wiki/Just-in-time_compilation

JIT covers a lot including straightforward translation of byte-code for 
a statically language, into native code.

In a language like Python, it's rather more elaborate.

And PyPy, as you hinted, is complelely different. I don't think it even 
attempts to JIT compile your example, it JIT compiles some repeatedly 
executed pathways in a program some way removed from the Python code or 
even its interpreter.

Or something like that... Whatever it is, it's more like magic. But what 
I started discussing here are ways of making a regular Python 
interpreter more efficient. I think that with projects such as PyPy, 
people are less interested with speeding up CPython, for one thing 
because it is not going to speed things up by ten times, so there seems 
little point.

-- 
BartC




From __peter__ at web.de  Tue Nov 10 08:40:59 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 10 Nov 2015 14:40:59 +0100
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n1ss5d$a0g$1@ger.gmane.org>

Ulli Horlacher wrote:

>     if u.getcode() == 200:
>       print(u.read(),file=szo,end='')
>       szo.close()
>     else:
>       die('cannot get %s - server reply: %d' % (szurl,u.getcode()))

More random remarks:

- print() gives the impression that you are dealing with text, and using it
  with binary strings will produce surprising results when you migrate to
  Python 3:

Python 2:

>>> from __future__ import print_function
>>> print(b"foo")
foo

Python 3:

>>> print(b"foo")
b'foo'

- with open(...) ensures that the file is closed when an exception occurs.
  It doesn't matter here as your script is going to die() anyway, but using
  with is a got habit to get into.
- consider shutil.copyfileobj to limit memory usage when dealing with data
  of arbitrary size.

Putting it together:

    with open(sz, "wb") as szo:
        shutil.copyfileobj(u, szo)





From framstag at rus.uni-stuttgart.de  Tue Nov 10 08:43:11 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Tue, 10 Nov 2015 13:43:11 +0000 (UTC)
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
 <mailman.209.1447161643.16136.python-list@python.org>
Message-ID: <n1ss9f$kvp$1@news2.informatik.uni-stuttgart.de>

Peter Otten <__peter__ at web.de> wrote:


> > It works with Linux, but not with Windows 7, where the downloaded 7za.exe
> > is corrupt: it has the wrong size, 589044 instead of 587776 Bytes.
> > 
> > Where is my error?
> 
> >     sz = path.join(fexhome,'7za.exe')
> >     szurl = "http://fex.belwue.de/download/7za.exe"
> > 
> >    try:
> >       szo = open(sz,'w')
> 
> Open the file in binary mode to avoid the translation of "\n" into "\r\n":
> 
>         szo = open(sz, 'wb')

Damn.. I should have known this!

Ok, now it works like on Linux. Windows is such a *BEEEP* *CENSORED*


> >     except (IOError,OSError) as e:
> >       die('cannot write %s - %s' % (sz,e.strerror))
> 
> Unrelated, but I recommend that you let the exceptions bubble up for easier 
> debugging.

die() is my debugging function :-)


> Python is not Perl ;)

*sigh* This is the problem ;-)
I am a Perl programmer for more than 25 years... 

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From framstag at rus.uni-stuttgart.de  Tue Nov 10 08:59:45 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Tue, 10 Nov 2015 13:59:45 +0000 (UTC)
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
 <mailman.210.1447162874.16136.python-list@python.org>
Message-ID: <n1st8h$l75$1@news2.informatik.uni-stuttgart.de>

Peter Otten <__peter__ at web.de> wrote:
> Ulli Horlacher wrote:
> 
> >     if u.getcode() == 200:
> >       print(u.read(),file=szo,end='')
> >       szo.close()
> >     else:
> >       die('cannot get %s - server reply: %d' % (szurl,u.getcode()))
> 
> More random remarks:

Always welcome - I am here to learn :-)


> - print() gives the impression that you are dealing with text, and using it
>   with binary strings will produce surprising results when you migrate to
>   Python 3:
> 
> Python 2:
> 
> >>> from __future__ import print_function

I already have this in my code, to make a later transition to Python 3
easier.


> >>> print(b"foo")
> foo
> 
> Python 3:
> 
> >>> print(b"foo")
> b'foo'

Bad.
Is there a better alternative to write arbitrary binary data?


> - with open(...) ensures that the file is closed when an exception occurs.
>   It doesn't matter here as your script is going to die() anyway, but using
>   with is a got habit to get into.

When an error occurs I do want to write more data, anyway.


> - consider shutil.copyfileobj to limit memory usage when dealing with data
>   of arbitrary size.
> 
> Putting it together:
> 
>     with open(sz, "wb") as szo:
>         shutil.copyfileobj(u, szo)

This writes the http stream binary to the file. without handling it
manually chunk by chunk?

Great. This would be my next task! You are answering my questions, before
I ask them! :-)

Background: I am rewriting my Perl program fexsend in Python.
fexsend transfers files up to TB range, see:
http://fex.rus.uni-stuttgart.de/



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From D.Strohl at F5.com  Tue Nov 10 10:06:54 2015
From: D.Strohl at F5.com (Dan Strohl)
Date: Tue, 10 Nov 2015 15:06:54 +0000
Subject: python PEP suggestion
In-Reply-To: <n1oi72$d2h$1@ger.gmane.org>
References: <cf746bff3459405cbdf04acabce99cae@seaexchmbx03.olympus.F5Net.com>
 <n1oi72$d2h$1@ger.gmane.org>
Message-ID: <d4fa569e629d4d9db387bf6fc63e28e4@seaexchmbx03.olympus.F5Net.com>

You mentioned that it is a bit contrary to how Python currently works, I am not sure I understand that, can you elaborate a bit?

<snip>
"Conditional execution, indexing (__index__), numeric conversions (__float__ also), and displaying are special cases related to syntax operations. <snip> You have left out the use of abstract base classes.  An iterable that can be used as a mapping can register itself as a mapping.  Json could check whether something is a sequence or mapping and iterate to get values or pairs of values."
</snip>

All of the above is true, and all of the above are various tools that can work (and I have used most of them from time to time).  However, there is a limit to how many different types of special methods that should be built in, built in, what if I want to build an object that would return a datetime or bytearray object as needed, or something more esoteric, or if I wanted to provide different types of data depending on the calling object?  

What I thinking about is something that allows the called object to return information based on the calling object, (or at least based on what the calling object wants to ask for) in a manner that makes the most sense.

This _seems_ like it fits pretty well with Python's module / library / orientation...  the library authors often do not know anything about the  ones using their objects (and should not have to).  With something like this, it allows the library author to have a "standard" way of saying, "I want data in this format".  That could be simply saying "I am json and want data that will work for me", or it could be saying "I want a datetime from you".  Then, even if the called / passed object is not mappable, or is a subclass of something totally different, the called object has the ability to respond in a way that the author of the called object chooses.

If, for example, I choose to implement an object as a mapping object (using __getitem__, subclassing userdict, using collections.abc.Mapping, or whatever), I am in general only going to be able to answer a call to object[key] one way.  I could certainly do a custom method or property but then we get back to both authors needing to coordinate more.

<snip>
Functions that unnecessarily restrict inputs to subclasses of list or dict will not be solved by this.
</snip>

Yup, it doesn't solve everything, it just provides another tool that people *could* use to write interoperable libraries and objects.

<snip>
Of course, the tranformation would be unidirectional.
</snip>

Again, yup, just like if I implemented "MyObject.__str__()", it does not guarantee that I did "MyObject('a_string')" it would work (and often doesn't).

<snip>
The excessive indents of 31 and 15 spaces make the rest of this post unnecessarily hard to read.
</snip>

Sorry about that, damn outlook tabs being expanded to stupid numbers I guess.  I will do better next time.<grin>.

Does any of that help?

Dan



-----Original Message-----
From: Python-list [mailto:python-list-bounces+d.strohl=f5.com at python.org] On Behalf Of Terry Reedy
Sent: Sunday, November 08, 2015 2:27 PM
To: python-list at python.org
Subject: Re: python PEP suggestion

On 11/6/2015 1:21 PM, Dan Strohl wrote:
> All,
>
> I wanted to run the following thought past the list as a possible PEP enhancement suggestion to see if it feels like something that is worth proposing.   I know it is not in the PEP format at this point, I can, and will, clean it up if needed, I am just trying to throw it against the wall at this point to see if it resonates... (or if it falls flat and goes "splat" <grin>).
>
> Thoughts?

At first glance, plausible, but I am not sure needed, and it seems a bit contrary to how Python currently works.



> New special method name to allow for more flexible object type casting/access, and extend type() to cast objects using this special method name.
>
> Overview:
>
> Have a new special method name that would allow a given objects to request information from another object in a given type, or to cast an object into a different type, and extend the built in type() function to use this.
>
> Rationale:
> There is currently __str__, __int__, and __bool__ that allow me to 
> tell an object how it should reply to a request for these types of 
> basic data types.  However if I want to access a copy of the objet in 
> dict form, or as a list, or if I am trying to convert something using 
> json, there is no standard way of doing that for a custom object (I 
> know I can do __getitem__ and/or __iter__, but I many processes don't 
> try these if the object is not a subclass of dict or list/tuple)

Conditional execution, indexing (__index__), numeric conversions (__float__ also), and displaying are special cases related to syntax operations.  Functions that unnecessarily restrict inputs to subclasses of list or dict will not be solved by this.  You have left out the use of abstract base classes.  An iterable that can be used as a mapping can register itself as a mapping.  Json could check whether something is a sequence or mapping and iterate to get values or pairs of values.  Of course, the tranformation would be unidirectional.

> Proposal:
> What I am proposing is something like:
>
> object.__cast__(self, to_class):
>                                """
>                                to_class: the class type that you wish to return.
>                                """

The excessive indents of 31 and 15 spaces make the rest of this post unnecessarily hard to read.

--
Terry Jan Reedy

--
https://mail.python.org/mailman/listinfo/python-list


From framstag at rus.uni-stuttgart.de  Tue Nov 10 10:51:05 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Tue, 10 Nov 2015 15:51:05 +0000 (UTC)
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
 <mailman.210.1447162874.16136.python-list@python.org>
 <n1st8h$l75$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n1t3p9$nq3$1@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
> Peter Otten <__peter__ at web.de> wrote:

> > - consider shutil.copyfileobj to limit memory usage when dealing with data
> >   of arbitrary size.
> > 
> > Putting it together:
> > 
> >     with open(sz, "wb") as szo:
> >         shutil.copyfileobj(u, szo)
> 
> This writes the http stream binary to the file. without handling it
> manually chunk by chunk?

I have a problem with it: There is no feedback for the user about the
progress of the transfer, which can last several hours.

For small files shutil.copyfileobj() is a good idea, but not for huge ones.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From __peter__ at web.de  Tue Nov 10 11:48:48 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 10 Nov 2015 17:48:48 +0100
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
 <mailman.210.1447162874.16136.python-list@python.org>
 <n1st8h$l75$1@news2.informatik.uni-stuttgart.de>
 <n1t3p9$nq3$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n1t75i$dgb$1@ger.gmane.org>

Ulli Horlacher wrote:

> Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
>> Peter Otten <__peter__ at web.de> wrote:
> 
>> > - consider shutil.copyfileobj to limit memory usage when dealing with
>> > data
>> >   of arbitrary size.
>> > 
>> > Putting it together:
>> > 
>> >     with open(sz, "wb") as szo:
>> >         shutil.copyfileobj(u, szo)
>> 
>> This writes the http stream binary to the file. without handling it
>> manually chunk by chunk?
> 
> I have a problem with it: There is no feedback for the user about the
> progress of the transfer, which can last several hours.
> 
> For small files shutil.copyfileobj() is a good idea, but not for huge
> ones.

Indeed. Have a look at the source code:

def copyfileobj(fsrc, fdst, length=16*1024):
    """copy data from file-like object fsrc to file-like object fdst"""
    while 1:
        buf = fsrc.read(length)
        if not buf:
            break
        fdst.write(buf)

As simple as can be. I suggested the function as an alternative to writing 
the loop yourself when your example code basically showed

dest.write(source.read())

For the huge downloads that you intend to cater to you probably want your 
script not just to print a dot on every iteration, you need expected 
remaining time, checksums, ability to stop and resume a download and 
whatnot.

Does the Perl code offer that? Then why rewrite?

Or are there Python libraries that do that out of the box? Can you reuse 
them?





From framstag at rus.uni-stuttgart.de  Tue Nov 10 12:21:24 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Tue, 10 Nov 2015 17:21:24 +0000 (UTC)
Subject: corrupt download with urllib2
References: <n1sq82$k3g$1@news2.informatik.uni-stuttgart.de>
 <mailman.210.1447162874.16136.python-list@python.org>
 <n1st8h$l75$1@news2.informatik.uni-stuttgart.de>
 <n1t3p9$nq3$1@news2.informatik.uni-stuttgart.de>
 <mailman.212.1447174160.16136.python-list@python.org>
Message-ID: <n1t92k$q1o$1@news2.informatik.uni-stuttgart.de>

Peter Otten <__peter__ at web.de> wrote:

> > I have a problem with it: There is no feedback for the user about the
> > progress of the transfer, which can last several hours.
> > 
> > For small files shutil.copyfileobj() is a good idea, but not for huge
> > ones.
> 
> Indeed. Have a look at the source code:
> 
> def copyfileobj(fsrc, fdst, length=16*1024):
>     """copy data from file-like object fsrc to file-like object fdst"""
>     while 1:
>         buf = fsrc.read(length)
>         if not buf:
>             break
>         fdst.write(buf)
> 
> As simple as can be

Oooops - that's all?!


> I suggested the function as an alternative to writing 
> the loop yourself when your example code basically showed

Good idea :-)


> For the huge downloads that you intend to cater to you probably want your 
> script not just to print a dot on every iteration, you need expected 
> remaining time, checksums, ability to stop and resume a download and 
> whatnot.
> 
> Does the Perl code offer that?

Of course, yes. For download AND upload.



> Then why rewrite?

There is no more a Perl compiler for windows which supports https.



> Or are there Python libraries that do that out of the box?

No.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From tjreedy at udel.edu  Tue Nov 10 12:49:19 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 10 Nov 2015 12:49:19 -0500
Subject: IDLE quits unexpectedly when about to open or creat a new file
In-Reply-To: <CAPTjJmoh5p2Fgd=zDgjNOEMsfkkgjOv7bcu7=8XcLQ1M=xNt+Q@mail.gmail.com>
References: <b42f7021-ab37-46da-a71f-13414c114606@googlegroups.com>
 <CAPTjJmoh5p2Fgd=zDgjNOEMsfkkgjOv7bcu7=8XcLQ1M=xNt+Q@mail.gmail.com>
Message-ID: <n1tan0$kbn$1@ger.gmane.org>

On 11/10/2015 6:01 AM, Chris Angelico wrote:
> On Tue, Nov 10, 2015 at 9:46 PM,  <trindadegoncalves at gmail.com> wrote:
>> I need help to find out what's going on. I did some research, but I couldn't find anything to solve this problem:
>>
>> - I open the IDLE program;

 From the Start menu icon, let us presume.

>> - I go to the 'File' menu;

Of the shell window, I presume.

>> - I select the 'New File' option

This should create an empty EditorWindow instance.

>> - IDLE quits.

Puzzling.  The shell window is a subclass of EditorWindow, so 
EditorWindow.__init__ has already run once -- without the extra stuff 
added by the subclass.

>> I run the IDLE version 3.3.3 on Windows 8.1 Pro.
>> Should I install the most recent version?

That would be a good idea in general.  But first try what Chris 
suggested below.  I am about half sure that the specific problem is on 
your system.  It is possible that you need to delete something in 
HOMEDIR/.idlerc/ but lets see what the error message is.  Have you been 
using IDLE a while, or just started?

> That sounds like a very interesting problem. Can you try running it
> from the command line, please? I'm not sure how to open one up from
> Win 8, but it should be in the Start menu somewhere, or possibly press
> Windows+R and type "cmd". With that up, type this:
>
> python -m idlelib.idle
>
> That should open up the same IDLE window that you know and recognize.
> Do the exact same thing that caused the unexpected termination, and
> then you should go back to the command prompt - hopefully with some
> sort of error message. Copy and paste that message (as text, please,
> not an image) into an email; that information could be very helpful.

-- 
Terry Jan Reedy



From none at mailinator.com  Tue Nov 10 15:36:52 2015
From: none at mailinator.com (mm0fmf)
Date: Tue, 10 Nov 2015 20:36:52 +0000
Subject: using binary in python
In-Reply-To: <mailman.214.1447186467.16136.python-list@python.org>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
Message-ID: <Hzs0y.118789$4v5.87935@fx37.am4>

On 10/11/2015 20:14, Dennis Lee Bieber wrote:
> The Ada language defines the end of Text file to consist of

It is 15 years this month since I last worked in place that used Ada. I 
think that calls for a wee dram to celebrate ;-)


From random832 at fastmail.com  Tue Nov 10 15:44:38 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 10 Nov 2015 15:44:38 -0500
Subject: using binary in python
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <e7j44b5mctqlkdl7uvehuc3f76oo3m8dl2@4ax.com>
Message-ID: <8737wda8jt.fsf@fastmail.com>

Dennis Lee Bieber <wlfraed at ix.netcom.com> writes:
> 	To be strict -- a text file has <some> system defined means of marking
> line endings. UNIX/Linux uses just a <LF> character; Windows uses the pair
> <CR><LF>. TRS-DOS used just <CR> for end of line. Some operating systems
> may have used count-delimited formats (and then there is the VMS FORTRAN
> segmented records with start and end segment bits).

Another possibility would be fixed-length records. The ANSI C standard
permits a maximum line length (no less than 254) and for trailing spaces
to be ignored.



From breamoreboy at yahoo.co.uk  Tue Nov 10 16:22:08 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 10 Nov 2015 21:22:08 +0000
Subject: using binary in python
In-Reply-To: <Hzs0y.118789$4v5.87935@fx37.am4>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
 <Hzs0y.118789$4v5.87935@fx37.am4>
Message-ID: <n1tn6c$m0m$1@ger.gmane.org>

On 10/11/2015 20:36, mm0fmf via Python-list wrote:
> On 10/11/2015 20:14, Dennis Lee Bieber wrote:
>> The Ada language defines the end of Text file to consist of
>
> It is 15 years this month since I last worked in place that used Ada. I
> think that calls for a wee dram to celebrate ;-)

Followed by a chorus or two of the Ian Dury song about Ada to put the 
icing on the cake.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From kent at z-sverige.nu  Tue Nov 10 16:29:01 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Tue, 10 Nov 2015 16:29:01 -0500
Subject: using binary in python
In-Reply-To: <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
Message-ID: <20151110212901.GA18609@z-sverige.nu>

On Mon, Nov 09, 2015 at 10:20:25PM -0800, Larry Hudson via Python-list wrote:
> Your questions are somewhat difficult to answer because you misunderstand
> binary.  The key is that EVERYTHING in a computer is binary.  There are NO
> EXCEPTIONS, it's all binary ALL the time.  The difference comes about in how
> this binary data is displayed and manipulated.  I want to emphasize, ALL the
> DATA is binary.
> 

Thanks alot for taking the time.
I get it now. I sort of, but not fully, misunderstood the conecpt of binary files. 
The thing I was after; and the thing Im playing with now after a more succesfull time with google, 
is writing more specific things to a file than just strings.
English is not my native language so please forgive me, but
I wanted to write specifc 16bit codes, and read them. And later play with bitwise operations on them. Sort of.
It might not make sense at all, but hey..  it doesnt have to.
Thanks anyway. :)


From none at mailinator.com  Tue Nov 10 17:17:37 2015
From: none at mailinator.com (mm0fmf)
Date: Tue, 10 Nov 2015 22:17:37 +0000
Subject: OT: Re: using binary in python
In-Reply-To: <mailman.216.1447189352.16136.python-list@python.org>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
 <Hzs0y.118789$4v5.87935@fx37.am4>
 <mailman.216.1447189352.16136.python-list@python.org>
Message-ID: <82u0y.114989$bA1.105280@fx41.am4>

On 10/11/2015 21:02, Dennis Lee Bieber wrote:
> On Tue, 10 Nov 2015 20:36:52 +0000, mm0fmf via Python-list
> <python-list at python.org> declaimed the following:
>
>> On 10/11/2015 20:14, Dennis Lee Bieber wrote:
>>> The Ada language defines the end of Text file to consist of
>>
>> It is 15 years this month since I last worked in place that used Ada. I
>> think that calls for a wee dram to celebrate ;-)
>
> 	Given that a dram is 1/8 of a "fluid ounce" that leads to the
> conclusion that a "wee dram" is based on US standard fluid once, vs British
> standard fluid ounce...
>
>
> 	My language preferences do tend to be the extremes: Python for quick
> throw-away stuff, Ada for more formal stuff (since it has a much more
> rigorous syntax than Pascal, Modula-2, C/C++, Java -- no optional block
> delimiters, no dangling else, etc.)
>
> 	Unfortunately, as a hobbyist dabbler at home, I can't justify the time
> to port an Ada compiler to Arduino, TIVA, Propeller, Beaglebone (though the
> latter may just be a case of porting the hardware access). So... I'm stuck
> with variants of C for those devices (again, excluding the Linux based
> Beaglebone)
>

I escaped having to produce new code in Ada, I merely had to run some 
scripts that added the compiled C binaries into the Ada gloop!

C user since 1983, C++ user since 2002, Python and C# since 2010. I 
regularly pinch myself that it seems to be painfully easy to be 
productive using Python compared to the other langauges!


From kent at z-sverige.nu  Tue Nov 10 17:27:21 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Tue, 10 Nov 2015 17:27:21 -0500
Subject: bitwise operator, bits dont go into bitbucket..?
Message-ID: <20151110222721.GA18905@z-sverige.nu>

Im reading about bitwise operators and is it true to say they dont work 100% as in C?
bitwise operators in C seem to result in bits going to the so called bitbucket. 
For example, 0b00000001. Shifting it >> 1  in C it seems to add on zero to the left and the 1 to the right gets throwned away.

But doing it in python just adds one more bit, from the left.  
That is, 0b00000001 >> 1     = 0b000000001.

Bitwise operators in C (when reading examples,) gives some time code that check specific bits by
shifting the bits left and right to make every bit but the specific one to zeros. 
As I understand bitwise operators in python, this is not possible then?


From rosuav at gmail.com  Tue Nov 10 17:33:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 11 Nov 2015 09:33:38 +1100
Subject: bitwise operator, bits dont go into bitbucket..?
In-Reply-To: <20151110222721.GA18905@z-sverige.nu>
References: <20151110222721.GA18905@z-sverige.nu>
Message-ID: <CAPTjJmo36yPX1CaUmY8zPgcwR-uJgsFbD7i1ctk4bdKYY-hzKw@mail.gmail.com>

On Wed, Nov 11, 2015 at 9:27 AM, kent nyberg <kent at z-sverige.nu> wrote:
> Im reading about bitwise operators and is it true to say they dont work 100% as in C?
> bitwise operators in C seem to result in bits going to the so called bitbucket.
> For example, 0b00000001. Shifting it >> 1  in C it seems to add on zero to the left and the 1 to the right gets throwned away.
>
> But doing it in python just adds one more bit, from the left.
> That is, 0b00000001 >> 1     = 0b000000001.

I'm not sure what you're expecting Python to do here, but
right-shifting the integer 1 results in the integer 0:

>>> 0b000001 >> 1
0

> Bitwise operators in C (when reading examples,) gives some time code that check specific bits by
> shifting the bits left and right to make every bit but the specific one to zeros.
> As I understand bitwise operators in python, this is not possible then?

If you want to check specific bits (in C or Python, either way), it's
much more common to use bitwise AND than bit shifts:

>>> 0b100011011101010110 & 0b000000010000
16
>>> print(bin(_))
0b10000

This will be either the same number as the right hand side (if the bit
had been set) or zero (if it hadn't).

ChrisA


From plucena24 at gmail.com  Tue Nov 10 17:36:04 2015
From: plucena24 at gmail.com (Pablo Lucena)
Date: Tue, 10 Nov 2015 17:36:04 -0500
Subject: Keeping context-manager object alive through function calls
Message-ID: <CAB_tDZw-3aMqzdwD728NNOxJsYYLXTZVdqQpErY1bz=Pz_LNkA@mail.gmail.com>

I am running into a bit of an issue with keeping a context manager open
through function calls. Here is what I mean:

There is a context-manager defined in a module which I use to open SSH
connections to network devices. The "setup" code handles opening the SSH
sessions and handling any issues, and the teardown code deals with
gracefully closing the SSH session. I normally use it as follows:

from manager import manager
def do_stuff(device):
    with manager(device) as conn:
        output = conn.send_command("show ip route")
        #process output...
    return processed_output

In order to keep the SSH session open and not have to re-establish it
across function calls, I would like to do add an argument to "do_stuff"
which can optionally return the SSH session along with the data returned
from the SSH session, as follows:

def do_stuff(device, return_handle=False):
    with manager(device) as conn:
        output = conn.send_command("show ip route")
        #process output...
        if return_handle:
            return (processed_output, conn)
        else:
            return processed_output


I would like to be able to call this function "do_stuff" from another
function, as follows, such that it signals to "do_stuff" that the SSH
handle should be returned along with the output.

def do_more_stuff(device):
    data, conn = do_stuff(device, return_handle=True)
    output = conn.send_command("show users")
    #process output...
    return processed_output

However the issue that I am running into is that the SSH session is closed,
due to the do_stuff function "returning" and triggering the teardown code
in the context-manager (which gracefully closes the SSH session).

I have tried converting "do_stuff" into a generator, such that its state is
suspended and perhaps causing the context-manager to stay open:

def do_stuff(device, return_handle=False):
    with manager(device) as conn:
        output = conn.send_command("show ip route")
        #process output...
        if return_handle:
            yield (processed_output, conn)
        else:
            yield processed_output

And calling it as such:

def do_more_stuff(device):
    gen = do_stuff(device, return_handle=True)
    data, conn = next(gen)
    output = conn.send_command("show users")
    #process output...
    return processed_output

However this approach does not seem to be working in my case, as the
context-manager gets closed, and I get back a closed socket.

Is there a better way to approach this problem? Maybe my generator needs
some more work...I think using a generator to hold state is the most
"obvious" way that comes to mind, but overall should I be looking into
another way of keeping the session open across function calls?

Thanks


-- 
*Pablo Lucena*


From ben+python at benfinney.id.au  Tue Nov 10 17:47:09 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 11 Nov 2015 09:47:09 +1100
Subject: Keeping context-manager object alive through function calls
References: <CAB_tDZw-3aMqzdwD728NNOxJsYYLXTZVdqQpErY1bz=Pz_LNkA@mail.gmail.com>
Message-ID: <85twoteaky.fsf@benfinney.id.au>

Pablo Lucena <plucena24 at gmail.com> writes:

> In order to keep the SSH session open and not have to re-establish it
> across function calls, I would like to do add an argument to
> "do_stuff" which can optionally return the SSH session along with the
> data returned from the SSH session, as follows:
>
> def do_stuff(device, return_handle=False):
>     with manager(device) as conn:
>         output = conn.send_command("show ip route")
>         #process output...
>         if return_handle:
>             return (processed_output, conn)
>         else:
>             return processed_output

Since you're making it the caller's responsibility to deal with the
context manager, why not require the caller to *provide* the context
manager in the first place::

    def do_stuff(conn):
        """ Do stuff via the device connection `conn`.

            :param conn: The context manager for the device connection.
            :return: The processed output.

            """
        with conn:
            output = conn.send_command("show ip route")
            #process output...
        return processed_output

Also, note that if you just unconditionally want to return the output,
do it *outside* the ?with? block.

Then your caller is the one responsible for creating the connection
manager, and has the option of interrogating it further if it needs to::

    bsu5000_conn = make_connection("bsu5000")
    gen = do_stuff(bsu5000_conn)
    do_more_things_with(bsu5000_conn)

-- 
 \       ?I don't know anything about music. In my line you don't have |
  `\                             to.? ?Elvis Aaron Presley (1935?1977) |
_o__)                                                                  |
Ben Finney



From tim at akwebsoft.com  Tue Nov 10 17:47:56 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Tue, 10 Nov 2015 13:47:56 -0900
Subject: Using subprocess to capture a progress line
Message-ID: <20151110224756.GA1944@mail.akwebsoft.com>

Using python 2.7.6 on ubuntu 14.04 
The application in question is run with bash and gnome-terminal :

I've written a command-line "wrapper" for youtube-dl, executing
youtube-dl as a subprocess.

------------------------------------------------------------------
youtube-dl reports download progress on one line. I.E. the line is
overwritten numerous times with no carriage return until the
downloading is finished.
------------------------------------------------------------------

The following code runs the youtube-dl command and reports each line
as output by youtube-dl
###########
    p = subprocess.Popen(list(args), stderr=subprocess.STDOUT,
                         stdout=subprocess.PIPE)
    while True:
        line = p.stdout.readline()
        if not line:
            break
        tmp = line.strip()
        print tmp
###########

However this method not does show the download progress _until_ the
download is complete. 

To clarify : follows is output from my app running youtube-dl.
I've annotated the line in question with '###'

[youtube] ZIgnHPqp0Dk: Downloading webpage
[youtube] ZIgnHPqp0Dk: Downloading video info webpage
[youtube] ZIgnHPqp0Dk: Extracting video information
[youtube] ZIgnHPqp0Dk: Downloading js player en_US-vfljDEtYP
[youtube] ZIgnHPqp0Dk: Downloading DASH manifest
[download] Destination: Someday Soon - Judy Collins 1969.avi.m4a
### the line below is not seen until download is finished.
[download] 100% of 7.58MiB in 00:12.85KiB/s ETA 00:00
[ffmpeg] Correcting container in "Someday Soon - Judy Collins 1969.avi.m4a"
[ffmpeg] Destination: Someday Soon - Judy Collins 1969.avi.mp3
Deleting original file Someday Soon - Judy Collins 1969.avi.m4a (pass -k to keep)

Is there a way to code subprocess so the the progress is being
shown? In my case lines being output aren't being shown unless a
newline is sent, or so I understand it.

FYI : the need for this function in this case is trivial, but the
solution will be enlightening for me and have other uses, I'll bet.

thanks

-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From rosuav at gmail.com  Tue Nov 10 17:53:43 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 11 Nov 2015 09:53:43 +1100
Subject: Keeping context-manager object alive through function calls
In-Reply-To: <CAB_tDZw-3aMqzdwD728NNOxJsYYLXTZVdqQpErY1bz=Pz_LNkA@mail.gmail.com>
References: <CAB_tDZw-3aMqzdwD728NNOxJsYYLXTZVdqQpErY1bz=Pz_LNkA@mail.gmail.com>
Message-ID: <CAPTjJmrqgZGqG=M1_p2GpSvKjjQA2T0s1qbp6-3vSoL0HTf5Tg@mail.gmail.com>

On Wed, Nov 11, 2015 at 9:36 AM, Pablo Lucena <plucena24 at gmail.com> wrote:
> And calling it as such:
>
> def do_more_stuff(device):
>     gen = do_stuff(device, return_handle=True)
>     data, conn = next(gen)
>     output = conn.send_command("show users")
>     #process output...
>     return processed_output

The first question needs to be: When *is* conn to be closed? What
you've done here is abandon all of the benefit of the context manager,
because it's no longer clear when you're done with the connection.
Here's an alternative: Turn your generator into another context
manager.

from contextlib import contextmanager

@contextmanager
def do_stuff(device):
    with manager(device) as conn:
        output = conn.send_command("show ip route")
        #process output...
        yield (processed_output, conn)

def do_stuff_now(device):
    with do_stuff(device) as (out, conn):
        return out

This forces you to separate the return_handle=True and
return_handle=False modes into two separate functions, but since one
is defined in terms of the other, you don't have a massive maintenance
burden. (Backward compatibility might have you call the first one
do_stuff_with_handle and the second one gets the name do_stuff. Or
whatever names make sense. Handwave.)

So now you can use do_stuff_now() the way you were using do_stuff(),
and if you want to keep using the handle afterward, you use it like
this:

def do_more_stuff(device):
    with do_stuff(device) as (data, conn):
        output = conn.send_command("show users")
        #process output...
        return processed_output

This guarantees that the device will be closed as you depart do_more_stuff.

There are other ways, but this is an easy way to build context
managers on top of context managers.

ChrisA


From kent at z-sverige.nu  Tue Nov 10 17:56:27 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Tue, 10 Nov 2015 17:56:27 -0500
Subject: bitwise operator, bits dont go into bitbucket..?
In-Reply-To: <CAPTjJmo36yPX1CaUmY8zPgcwR-uJgsFbD7i1ctk4bdKYY-hzKw@mail.gmail.com>
References: <20151110222721.GA18905@z-sverige.nu>
 <CAPTjJmo36yPX1CaUmY8zPgcwR-uJgsFbD7i1ctk4bdKYY-hzKw@mail.gmail.com>
Message-ID: <20151110225627.GA19339@z-sverige.nu>

On Wed, Nov 11, 2015 at 09:33:38AM +1100, Chris Angelico wrote:
> On Wed, Nov 11, 2015 at 9:27 AM, kent nyberg <kent at z-sverige.nu> wrote:

> 
> If you want to check specific bits (in C or Python, either way), it's
> much more common to use bitwise AND than bit shifts:
> 
> >>> 0b100011011101010110 & 0b000000010000
> 16
> >>> print(bin(_))
> 0b10000
> 

So, to check if 0b010[this one bit]010 is set,   i do   & 0b0001000

That is,  I set just that one to 1 in the other and then the & operator will make it return
0 if its not set. Since every other is zero, the return will be zero if its not. Since & operator sets 0
if not both are 1. Right?  

Id so, Thanks.   

My misunderstanding was that
0b01000   (for example,) first could be shifted left. To become 0b10000.
And then shifted right to become 0b00001. 
The shifting would turn every other digit to 0 and leave only the wanted one untouched. 
That way, I could check if its 0 or 1.  If you understand my own logic of how it works.
But I got it wrong,  and I think I know how to do it with & operator.

> This will be either the same number as the right hand side (if the bit
> had been set) or zero (if it hadn't).
> 
> ChrisA
> -- 
> https://mail.python.org/mailman/listinfo/python-list


From rosuav at gmail.com  Tue Nov 10 18:16:17 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 11 Nov 2015 10:16:17 +1100
Subject: bitwise operator, bits dont go into bitbucket..?
In-Reply-To: <20151110225627.GA19339@z-sverige.nu>
References: <20151110222721.GA18905@z-sverige.nu>
 <CAPTjJmo36yPX1CaUmY8zPgcwR-uJgsFbD7i1ctk4bdKYY-hzKw@mail.gmail.com>
 <20151110225627.GA19339@z-sverige.nu>
Message-ID: <CAPTjJmoTksZEwiUQy=zh8bRnO1gK8dxLV778Ns3zCNYacc_M7w@mail.gmail.com>

On Wed, Nov 11, 2015 at 9:56 AM, kent nyberg <kent at z-sverige.nu> wrote:
> So, to check if 0b010[this one bit]010 is set,   i do   & 0b0001000
>
> That is,  I set just that one to 1 in the other and then the & operator will make it return
> 0 if its not set. Since every other is zero, the return will be zero if its not. Since & operator sets 0
> if not both are 1. Right?
>
> Id so, Thanks.

Exactly! It's common to have named constants for things that matter to
you; for example, you can find out if a file/directory is
world-writable like this:

>>> import stat
>>> os.stat("/").st_mode & stat.S_IWOTH
0
>>> os.stat("/tmp").st_mode & stat.S_IWOTH
2

So my root directory is not world writable (result of zero), and the
/tmp directory is. (This is not surprising.) The S_IWOTH constant is
simply the integer 2, but giving it a name makes it a bit easier to
see what's going on in the code. (Not that the name is abundantly
clear... it could be improved on. But it's better than just '2'.)

> My misunderstanding was that
> 0b01000   (for example,) first could be shifted left. To become 0b10000.
> And then shifted right to become 0b00001.
> The shifting would turn every other digit to 0 and leave only the wanted one untouched.
> That way, I could check if its 0 or 1.  If you understand my own logic of how it works.
> But I got it wrong,  and I think I know how to do it with & operator.

That's true of right shifting, but when you left shift, you're
depending on a specific word size. Even in C, it's possible to get
burned by that (eg when you move from 32-bit to 64-bit), and in
Python, integers have infinite size. If you definitely want that
behaviour, you can do this:

(0b01000 << 1) & 0b11111

which will mask off your result to just five bits, giving you the
"drop the top bit" effect. But for bit testing and manipulation, it's
way easier to use AND/OR/XOR than shifts.

The one place you might want to use bit shifts is in _creating_ those
constants. For instance:

STYLE_FOO = 1 << 0
STYLE_BAR = 1 << 1
STYLE_BAZ = 1 << 2
STYLE_ABC = 1 << 3
STYLE_QWE = 1 << 4
STYLE_XYZ = 1 << 5

>From this table, it's obvious that they've been assigned successive
bits. You can do the same with an enumeration:

>>> class Style(enum.IntEnum):
...     FOO = 1 << 0
...     BAR = 1 << 1
...     BAZ = 1 << 2
...     ABC = 1 << 3
...     QWE = 1 << 4
...     XYZ = 1 << 5
...
>>> Style.BAR
<Style.BAR: 2>
>>> Style.QWE
<Style.QWE: 16>

And then you can test to see if some style was chosen:

>>> widget = Style.FOO | Style.QWE
>>> widget & Style.ABC
0
>>> widget & Style.QWE
16

Does that make things a bit easier to read?

ChrisA


From rosuav at gmail.com  Tue Nov 10 18:28:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 11 Nov 2015 10:28:26 +1100
Subject: Using subprocess to capture a progress line
In-Reply-To: <20151110224756.GA1944@mail.akwebsoft.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
Message-ID: <CAPTjJmrhYG5xL_Kru8Jr7R=exvp6caooQ4U2HDJByvVaTsi=sA@mail.gmail.com>

On Wed, Nov 11, 2015 at 9:47 AM, Tim Johnson <tim at akwebsoft.com> wrote:
> I've written a command-line "wrapper" for youtube-dl, executing
> youtube-dl as a subprocess.
>
> ------------------------------------------------------------------
> youtube-dl reports download progress on one line. I.E. the line is
> overwritten numerous times with no carriage return until the
> downloading is finished.
> ------------------------------------------------------------------
>

Sounds to me like a possible buffering problem. But since youtube-dl
is implemented in Python, you might find it easier to "pip install
youtube_dl" and work with the methods directly:

>>> import youtube_dl
>>> youtube_dl.YoutubeDL().download(["m39ydsOPSww"])

Should be possible to manipulate around the outside of that.

ChrisA


From tim at akwebsoft.com  Tue Nov 10 18:51:02 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Tue, 10 Nov 2015 14:51:02 -0900
Subject: Using subprocess to capture a progress line
In-Reply-To: <CAPTjJmrhYG5xL_Kru8Jr7R=exvp6caooQ4U2HDJByvVaTsi=sA@mail.gmail.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAPTjJmrhYG5xL_Kru8Jr7R=exvp6caooQ4U2HDJByvVaTsi=sA@mail.gmail.com>
Message-ID: <20151110235102.GB1944@mail.akwebsoft.com>

* Chris Angelico <rosuav at gmail.com> [151110 14:35]:
> On Wed, Nov 11, 2015 at 9:47 AM, Tim Johnson <tim at akwebsoft.com> wrote:
> > I've written a command-line "wrapper" for youtube-dl, executing
> > youtube-dl as a subprocess.
> >
> > ------------------------------------------------------------------
> > youtube-dl reports download progress on one line. I.E. the line is
> > overwritten numerous times with no carriage return until the
> > downloading is finished.
> > ------------------------------------------------------------------
> >
> 
> Sounds to me like a possible buffering problem. But since youtube-dl
> is implemented in Python, you might find it easier to "pip install
> youtube_dl" and work with the methods directly:
> 
> >>> import youtube_dl
> >>> youtube_dl.YoutubeDL().download(["m39ydsOPSww"])

  Frankly, I'd prefer - in the long run - to use youtube_dl (the
  module).

  But, when I do as you have suggested (and have tried previously) I
  get the following:

  youtube_dl.utils.DownloadError: ERROR: no suitable InfoExtractor

  I've briefly researched the error and so far haven't come up with an
  solution - guessing that other setup code is needed ...

  As for the buffering issue, at this point, I'll try  using a
  lower-level function like sys.stdout.write when the line 
  tests for '[download]' and 'ETA'.

  :) more elegant solutions welcome. I do intend to investigate
  using youtube_dl, once subprocess has been dealt with.

  thanks for the quick reply

-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From random832 at fastmail.com  Tue Nov 10 19:03:55 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 10 Nov 2015 19:03:55 -0500
Subject: using binary in python
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
 <Hzs0y.118789$4v5.87935@fx37.am4>
 <pdm44bt0qpn6d9rgm7vtm9035a3iv3u67r@4ax.com>
Message-ID: <87ziylfllg.fsf@fastmail.com>

Dennis Lee Bieber <wlfraed at ix.netcom.com> writes:
>
> 	Given that a dram is 1/8 of a "fluid ounce" that leads to the
> conclusion that a "wee dram" is based on US standard fluid once,

29.6 ml

> vs British standard fluid ounce...

28.4 ml

It's our _pints_ that are smaller than yours, not our ounces.



From random832 at fastmail.com  Tue Nov 10 19:04:16 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 10 Nov 2015 19:04:16 -0500
Subject: using binary in python
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
 <Hzs0y.118789$4v5.87935@fx37.am4>
 <pdm44bt0qpn6d9rgm7vtm9035a3iv3u67r@4ax.com>
Message-ID: <87y4e5flkv.fsf@fastmail.com>

Dennis Lee Bieber <wlfraed at ix.netcom.com> writes:
> 	Given that a dram is 1/8 of a "fluid ounce" that leads to the
> conclusion that a "wee dram" is based on US standard fluid once,

29.6 ml

> vs British standard fluid ounce...

28.4 ml

It's our _pints_ that are smaller than yours, not our ounces.



From tim at akwebsoft.com  Tue Nov 10 19:14:36 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Tue, 10 Nov 2015 15:14:36 -0900
Subject: Using subprocess to capture a progress line
In-Reply-To: <20151110235102.GB1944@mail.akwebsoft.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAPTjJmrhYG5xL_Kru8Jr7R=exvp6caooQ4U2HDJByvVaTsi=sA@mail.gmail.com>
 <20151110235102.GB1944@mail.akwebsoft.com>
Message-ID: <20151111001436.GC1944@mail.akwebsoft.com>

* Tim Johnson <tim at akwebsoft.com> [151110 14:55]:
> * Chris Angelico <rosuav at gmail.com> [151110 14:35]:
> > On Wed, Nov 11, 2015 at 9:47 AM, Tim Johnson <tim at akwebsoft.com> wrote:
> > > I've written a command-line "wrapper" for youtube-dl, executing
> > > youtube-dl as a subprocess.
> > >
> > > ------------------------------------------------------------------
> > > youtube-dl reports download progress on one line. I.E. the line is
> > > overwritten numerous times with no carriage return until the
> > > downloading is finished.
> > > ------------------------------------------------------------------
> > >
> > 
> > Sounds to me like a possible buffering problem. But since youtube-dl
> > is implemented in Python, you might find it easier to "pip install
> > youtube_dl" and work with the methods directly:
> 
>   As for the buffering issue, at this point, I'll try  using a
>   lower-level function like sys.stdout.write when the line 
>   tests for '[download]' and 'ETA'.
    That method doesn't work ... so far. Oh well.
-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From torriem at gmail.com  Tue Nov 10 19:19:14 2015
From: torriem at gmail.com (Michael Torrie)
Date: Tue, 10 Nov 2015 17:19:14 -0700
Subject: using binary in python
In-Reply-To: <20151110212901.GA18609@z-sverige.nu>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <20151110212901.GA18609@z-sverige.nu>
Message-ID: <56428982.9010205@gmail.com>

On 11/10/2015 02:29 PM, kent nyberg wrote:
> On Mon, Nov 09, 2015 at 10:20:25PM -0800, Larry Hudson via Python-list wrote:
>> Your questions are somewhat difficult to answer because you misunderstand
>> binary.  The key is that EVERYTHING in a computer is binary.  There are NO
>> EXCEPTIONS, it's all binary ALL the time.  The difference comes about in how
>> this binary data is displayed and manipulated.  I want to emphasize, ALL the
>> DATA is binary.
>>
> 
> Thanks alot for taking the time.
> I get it now. I sort of, but not fully, misunderstood the conecpt of binary files. 
> The thing I was after; and the thing Im playing with now after a more succesfull time with google, 
> is writing more specific things to a file than just strings.
> English is not my native language so please forgive me, but
> I wanted to write specifc 16bit codes, and read them. And later play with bitwise operations on them. Sort of.
> It might not make sense at all, but hey..  it doesnt have to.
> Thanks anyway. :)

You're correct; it doesn't make that much sense.  If it were me I'd
write out my numbers in text format to the file. You can always read
them back in and covert them to a number.

Just a quick couple of notes on "binary" vs "text".  In the old days on
Windows, the difference between "binary" and "ascii" when it came to
file reading was simply the interpretation of the end-of-line marker.
Whenever you wrote out a \n, it got silently converted to two bytes,
0x0d 0x0a.  If you were trying to write a jpeg file, for example, this
would corrupt things as you well know.  In the Unix world, we never
worried about such things because the end-of-line marker was simple
0x0a.  It was never translated and never was expanded silently.  So when
it came to how we worked with files, there was no difference between
binary and ascii modes as far as the C library open() was concerned.

Now with Python 3, we now again do have to think about the distinction
between "text" and "binary" when working with files.  If we want to open
a text file, we have to open it while specifying the expected text
encoding, whether that is UTF-8, UCS-2, UTF-16, or some other old and
esoteric encoding.  That is to say when Python reads from a text file,
there is always going to be a decoding process going on where text file
bytes are read in, and then converted into unicode characters.  When
writing a text file out, unicode characters have to be encoded into a
series of bytes.  If Python knows what encoding we want, then it can do
this automatically as we write to the file.

In Python 3 opening a file for binary will read in raw bytes and you can
manipulate them however you wish.



From tim at akwebsoft.com  Tue Nov 10 19:31:21 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Tue, 10 Nov 2015 15:31:21 -0900
Subject: Using subprocess to capture a progress line
In-Reply-To: <20151110235102.GB1944@mail.akwebsoft.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAPTjJmrhYG5xL_Kru8Jr7R=exvp6caooQ4U2HDJByvVaTsi=sA@mail.gmail.com>
 <20151110235102.GB1944@mail.akwebsoft.com>
Message-ID: <20151111003121.GD1944@mail.akwebsoft.com>

* Tim Johnson <tim at akwebsoft.com> [151110 14:55]:
> * Chris Angelico <rosuav at gmail.com> [151110 14:35]:
> > On Wed, Nov 11, 2015 at 9:47 AM, Tim Johnson <tim at akwebsoft.com> wrote:
> > > I've written a command-line "wrapper" for youtube-dl, executing
> > is implemented in Python, you might find it easier to "pip install
> > youtube_dl" and work with the methods directly:
<<...> > 
> > >>> import youtube_dl
> > >>> youtube_dl.YoutubeDL().download(["m39ydsOPSww"])
> 
>   Frankly, I'd prefer - in the long run - to use youtube_dl (the
>   module).
> 
>   But, when I do as you have suggested (and have tried previously) I
>   get the following:
> 
>   youtube_dl.utils.DownloadError: ERROR: no suitable InfoExtractor
> 
    It looks as if the developers are constantly upgrading. I just
	upgraded youtube_dl

	sudo pip install --upgrade youtube_dl

	And ran the code which is provided under the topic 
	"EMBEDDING YOUTUBE-DL"
	at 
	https://github.com/rg3/youtube-dl/blob/master/README.md

	At I got a successful download, AFAICS
-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From shriphanip at gmail.com  Tue Nov 10 20:09:37 2015
From: shriphanip at gmail.com (shriphanip at gmail.com)
Date: Tue, 10 Nov 2015 17:09:37 -0800 (PST)
Subject: Swig + Numpy.i with a const int16_t pointer
Message-ID: <05ae95fa-68f0-43ca-8b36-04a827c5d878@googlegroups.com>

I am trying to wrap the following function with SWIG so I can call it from Python. The signature is:

```
int WebRtcVad_Process(VadInst* handle, int fs, const int16_t* audio_frame, size_t frame_length);
```

I have the following SWIG file: https://gist.github.com/shriphani/92c587ea4c32bafc9d97

At the end of this, I get the following error: webrtc_vad.i:22: Warning 453: Can't apply (int16_t const *IN_ARRAY1,unsigned int DIM1). No typemaps are defined.

If I drop the unsigned bit in the signature, then it compiles fine but the function signature is carried as-is (i.e. the function expects an int pointer and all that business).

Does anyone have a solution?

Regards,
Shriphani


From steve at pearwood.info  Tue Nov 10 20:10:56 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 11 Nov 2015 12:10:56 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <854mgufkqm.fsf@benfinney.id.au>
 <201511101033.tAAAXYZP001340@fido.openend.se>
 <mailman.207.1447157674.16136.python-list@python.org>
Message-ID: <564295a3$0$1585$c3e8da3$5496439d@news.astraweb.com>

On Tue, 10 Nov 2015 11:14 pm, Ben Finney wrote:

>> Python -- yes, even CPython -- has a runtime compiler. When you import
>> a module, it is compiled (if needed) just before the import. Likewise,
>> when you call the `compile`, `eval` or `exec` built-ins, the compiler
>> operates.
>>
>> I'm not calling this a JIT compiler, because the simple-minded
>> compilation performed by `compile` etc doesn't use any run-time
>> information. It just statically compiles the code to byte-code.
> 
> That's what I though. I'm aware of JIT compilers, and was pretty sure
> Python doesn't have them. 

What do you think PyPy is then?

CPython is intentionally a pretty simple-minded compiler. Even no-brainer
constant folding is mildly controversial among some Python devs. But
CPython isn't "Python", it is just the reference implementation. Nuitka
aims to be an optimized AOT (Ahead Of Time) Python compiler, and PyPy is
already a state of the art (if not cutting edge) JIT Python compiler.

And if Victor Skinner's experimental FAT Python works out, even CPython
itself will gain some simple JIT techniques, rather similar to what Psycho
was doing ten years ago.


> What's more, if it operates at a whole-module 
> level, and not later than when the module is imported.

Now you're getting into implementation details of the JIT compiler. Can it
track entities across modules? How exactly does it operate?

PyPy is a "tracing JIT", which (if I have understood correctly) means it
actually analyses the code as it runs, using knowledge gained at runtime to
dynamically decide what to compile. This means that PyPy is best suited to
code that has long-running loops, and not well suited to scripts that don't
run for a long time. But another (hypothetical) JIT compiler might be more
like Psycho.


> Under those conditions, I maintain my objection to the proposed
> optimisation.
> 
> The proposal is explicitly for optimisations made by the Python
> compiler. As proposed, it only seems to be worthwhile once Python no
> longer has a distinct ?compiler? and ?interpreter? is dissolved. Until
> then, it seems pointless.

Python has not had a distinct "compiler" and "interpreter" since about
version 0.1. The execution module of Python as a dynamic byte-code
compiled, interpreted language with eval and exec *depends* on the compiler
being available during the execution phase, i.e. at runtime.

Some of the things I've suggested already exist, and have proven that they
work: Psycho and PyPy, to say nothing of similar technologies for other
equally dynamic languages such as Javascript and Smalltalk. Others are
state of the art compiler techniques -- they might not have been applied to
*Python* but that's only because nobody has got around to it, not because
it can't be done.

I daresay that there are implementation challenges to making Python faster
than it is without compromising on the semantics of the language, but there
is nothing fundamentally impossible about the idea.

Ben, I know that the IT crowd is rather conservative, and the Python
community even more so, but at the point where you are denying the
possibility of technologies which *already exist* I think that things have
got a bit out of hand. It's a bit like somebody getting on Twitter to
tweet "A globally interconnected communication network allowing computers
all over the world to communicate? Impossible! And even if it were
possible, nobody would use it."

;-)

 

-- 
Steven



From orgnut at yahoo.com  Tue Nov 10 22:53:18 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Tue, 10 Nov 2015 19:53:18 -0800
Subject: using binary in python
In-Reply-To: <mailman.214.1447186467.16136.python-list@python.org>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.214.1447186467.16136.python-list@python.org>
Message-ID: <Gq2dne_GjoQtJt_LnZ2dnUU7-e-dnZ2d@giganews.com>

On 11/10/2015 12:14 PM, Dennis Lee Bieber wrote:
> On Mon, 9 Nov 2015 22:20:25 -0800, Larry Hudson via Python-list
> <python-list at python.org> declaimed the following:
>
>> Of course it can.  The only difference a text file and a binary file is the way it's opened.
>> Text files are opened with 'r' or 'w', while binary files are opened with 'rb' or 'wb'.  Being
>> different modes, the reading/writing is handled differently.  One obvious difference, the lines
>> of a text file are marked by ending them with a newline character, so it's easy to read/write
>> the text line-by-line.  But the data in a binary file is completely arbitrary and is much
>
> 	To be strict -- a text file has <some> system defined means of marking
> line endings. UNIX/Linux uses just a <LF> character; Windows uses the pair
> <CR><LF>. TRS-DOS used just <CR> for end of line. Some operating systems
> may have used count-delimited formats (and then there is the VMS FORTRAN
> segmented records with start and end segment bits).
>
The main purpose of my message was to get across the idea of separating the actual data (as 
binary values) and the way this data is displayed (to the user/programmer).  They are two 
entirely different concepts, and the OP was obviously confused about this.  But of course, 
you're right -- I was careless/imprecise in some of my descriptions.

      -=- Larry -=-



From steve+comp.lang.python at pearwood.info  Wed Nov 11 02:18:59 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 11 Nov 2015 18:18:59 +1100
Subject: Keeping context-manager object alive through function calls
References: <mailman.221.1447194972.16136.python-list@python.org>
Message-ID: <5642ebe7$0$1516$c3e8da3$5496439d@news.astraweb.com>

On Wednesday 11 November 2015 09:36, Pablo Lucena wrote:

> I am running into a bit of an issue with keeping a context manager open
> through function calls. Here is what I mean:
[...]
> In order to keep the SSH session open and not have to re-establish it
> across function calls, I would like to do add an argument to "do_stuff"
> which can optionally return the SSH session along with the data returned
> from the SSH session, as follows:

That won't work. The whole point of the "with" statement is to automatically 
close the context manager when you leave the with statement. If you don't 
want it automatically closed, *don't use with*.

There's nothing wrong with manually opening and closing the connection, if 
that's what you need. Open the ssh connection, pass it to your various 
functions, and close it only when you are done with it.

Or, and this might be a better solution, move the with block up a level. 
Instead of putting it in "do_stuff" and the assorted other functions, open 
the connection *before* you call these functions:


def main():
    setup()
    with manager(device) as conn:
        do_stuff(conn)
        do_more_stuff(conn)
        do_even_more_stuff(conn)
    # Now we're finally done.
    sys.exit(0)



[...]
> I have tried converting "do_stuff" into a generator, such that its state
> is suspended and perhaps causing the context-manager to stay open:
[...]
> However this approach does not seem to be working in my case, as the
> context-manager gets closed, and I get back a closed socket.
> 
> Is there a better way to approach this problem? Maybe my generator needs
> some more work...I think using a generator to hold state is the most
> "obvious" way that comes to mind, but overall should I be looking into
> another way of keeping the session open across function calls?

You might be able to get some awful hack using generators working, but it 
will be ugly, confusing and fragile. This is a sign you are abusing the 
context manager and using it in a way that goes against the design of the 
feature. Consider some future maintainer (perhaps even yourself, in six 
months or a year), reading the code, and completely puzzled why the SSH 
connection isn't closed when the with block is exited.



-- 
Steve



From steve+comp.lang.python at pearwood.info  Wed Nov 11 02:38:30 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Wed, 11 Nov 2015 18:38:30 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net>
 <n1nb0f$atn$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
 <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
 <n1sr6n$d6f$1@dont-email.me>
Message-ID: <5642f079$0$1527$c3e8da3$5496439d@news.astraweb.com>

On Wednesday 11 November 2015 00:26, BartC wrote:

> Does the Python language specify how it is to be compiled and executed?

Not in so many words, but there are limitations on what you can do based on 
the specified semantics of Python.

But so long as you meet those semantics, you can implement them any 
reasonable way you like:

- CPython uses one specific implementation written in C;

- PyPy uses a powerful tracing JIT compiler written in an intermediate 
language RPython;

- IronPython uses the .Net CLR virtual machine;

- Jython uses the Java virtual machine;

- there was an experimental version of Python using the Parrot virtual 
machine;

etc. Those implementations will naturally perform differently. For example, 
I believe that IronPython *generally* is faster than CPython, with some 
exceptions.


> If not, then you can use any interpretation you like, provided the
> program gives the expected results.

Precisely.

> That includes using a static compilation pass that generates byte-code,
> even if it is only done immediately before running the main module, or
> just before performing an import operation on another.

That's what CPython already does.


> Anything is possible. But the chances are that if you are running
> CPython, then it will probably include a discrete byte-code compiler.

Since compile, eval and exec are Python built-ins, if it doesn't include a 
byte-code compiler, it isn't Python. It's just a subset of Python.



>> execute this Python snippet:
>>
>> result = x + 2
[...]
>> But a JIT compiler gets to compile code right before that line is due to
>> execute. By the time the JIT compiler gets to see that line of code, it
>> can already know whether or not name "x" exists, and if so, which
>> namespace it is in. It knows what value "x" has.
> 
> How does it do that? How is the 'x+1' even stored in the machine?

That depends entirely on the implementation of the compiler.


> Suppose the preceding lines are:
> 
>     if random+bit()==1:
>        x=920.5
>     else:
>        x=[8,5,4,9,1,7,6,3,2]
> 
> or:
> 
>     if some_condition: del x
> 
> it will probably know as much about x as the static compiler does!

Not at all. The difference is, having called rand_bit() and tested whether 
it is 1, the compiler takes a branch:

- it binds 920.5 to x

- or it binds [8, 5, 4, ...] to x

The compiler knows which branch it just took, *because it just took it*. If 
it doesn't know which branch it just took, it isn't a JIT compiler! It's 
just a classic, old-fashioned interpreter with no smarts.

So, having just bound some value to x, the compiler knows that x is a float 
(or a list), and can optimize the next instruction, which is "x + 1".

CPython can't do that, because it doesn't have the infrastructure to perform 
the necessary book-keeping. And it probably never will do that, because 
Guido likes the fact that CPython is simple enough for him to understand. 
He's happy for PyPy and other third-party implementations to do the clever 
stuff.



-- 
Steven



From marko at pacujo.net  Wed Nov 11 03:30:41 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 11 Nov 2015 10:30:41 +0200
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
 <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
 <n1sr6n$d6f$1@dont-email.me>
 <5642f079$0$1527$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87wptpey4u.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> Since compile, eval and exec are Python built-ins, if it doesn't
> include a byte-code compiler, it isn't Python. It's just a subset of
> Python.

compile() can be implemented trivially, or in any other manner. It
simply needs to return a "code object." I suspect even a string might
work as a code object.


Marko


From marko at pacujo.net  Wed Nov 11 03:30:41 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 11 Nov 2015 10:30:41 +0200
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me>
 <mailman.135.1446998410.16136.python-list@python.org>
 <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
 <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
 <n1sr6n$d6f$1@dont-email.me>
 <5642f079$0$1527$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87wptpey4u.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> Since compile, eval and exec are Python built-ins, if it doesn't
> include a byte-code compiler, it isn't Python. It's just a subset of
> Python.

compile() can be implemented trivially, or in any other manner. It
simply needs to return a "code object." I suspect even a string might
work as a code object.


Marko


From kwpolska at gmail.com  Wed Nov 11 04:48:03 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Wed, 11 Nov 2015 10:48:03 +0100
Subject: Using subprocess to capture a progress line
In-Reply-To: <20151110224756.GA1944@mail.akwebsoft.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
Message-ID: <CAMw+j7LZH44RnPXgP4XVDiv62uJ_iFmsEm17QpsmNBSDr=uvJw@mail.gmail.com>

On 10 November 2015 at 23:47, Tim Johnson <tim at akwebsoft.com> wrote:
> Using python 2.7.6 on ubuntu 14.04
> The application in question is run with bash and gnome-terminal :
>
> I've written a command-line "wrapper" for youtube-dl, executing
> youtube-dl as a subprocess.
>
> ------------------------------------------------------------------
> youtube-dl reports download progress on one line. I.E. the line is
> overwritten numerous times with no carriage return until the
> downloading is finished.
> ------------------------------------------------------------------
>
> The following code runs the youtube-dl command and reports each line
> as output by youtube-dl
> ###########
>     p = subprocess.Popen(list(args), stderr=subprocess.STDOUT,
>                          stdout=subprocess.PIPE)
>     while True:
>         line = p.stdout.readline()
>         if not line:
>             break
>         tmp = line.strip()
>         print tmp
> ###########
>
> However this method not does show the download progress _until_ the
> download is complete.

There is no \n character at the end ? which means that
p.stdout.readline() cannot return. In fact, if you printed repr() of
the line you read, you would get this:

b'\r[download]  54.9% of 2.73MiB at 26.73KiB/s ETA 00:47\r[download]
55.0% of 2.73MiB at 79.33KiB/s ETA 00:15\r?snip?\r[download] 100% of
2.73MiB in 00:01\n'

The download line is implemented using \r, which is the carriage
return character (return to the first character), and then by
overwriting characters that were already printed.

The solution? There are numerous. I?ll help you by obscuring the worst one.

(1) [recommended] figure out how to make youtube_dl work as a library,
read its main file to figure out the problem. Don?t mess with
subprocess.
(2) [don?t do it] do you need to intercept the lines? If you don?t set
stderr= and stdout=, things will print just fine.
(3) [DON?T DO IT] .ernq() punenpgre ol punenpgre naq znxr n zrff.

PS. Thank you for setting a sensible Reply-To header on your messages.
Which is something the list should be doing.

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From steve at pearwood.info  Wed Nov 11 06:20:26 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 11 Nov 2015 22:20:26 +1100
Subject: Question about math.pi is mutable
References: <n1kshk$brb$1@dont-email.me> <n1o25a$3s3$1@dont-email.me>
 <mailman.142.1447005691.16136.python-list@python.org>
 <n1o5sl$joc$1@dont-email.me>
 <mailman.152.1447024427.16136.python-list@python.org>
 <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au>
 <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com>
 <85y4e8ggrj.fsf@benfinney.id.au>
 <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
 <85twowgfm6.fsf@benfinney.id.au>
 <CAPTjJmq--XE006MzxNe_3d_rmOP9GYxM_AxMF7Nh3d3RQbBx4g@mail.gmail.com>
 <mailman.160.1447031104.16136.python-list@python.org>
 <564081e7$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.186.1447098364.16136.python-list@python.org>
 <56415873$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.198.1447135830.16136.python-list@python.org>
 <5641d63a$0$1603$c3e8da3$5496439d@news.astraweb.com>
 <n1sr6n$d6f$1@dont-email.me>
 <5642f079$0$1527$c3e8da3$5496439d@news.astraweb.com>
 <87wptpey4u.fsf@elektro.pacujo.net>
Message-ID: <5643247b$0$1598$c3e8da3$5496439d@news.astraweb.com>

On Wed, 11 Nov 2015 07:30 pm, Marko Rauhamaa wrote:

> Steven D'Aprano <steve+comp.lang.python at pearwood.info>:
> 
>> Since compile, eval and exec are Python built-ins, if it doesn't
>> include a byte-code compiler, it isn't Python. It's just a subset of
>> Python.
> 
> compile() can be implemented trivially, or in any other manner. It
> simply needs to return a "code object." I suspect even a string might
> work as a code object.

Sure. That's just quality of implementation. In principle, a Python
interpreter might even operate without any byte-code at all, parsing each
line of code before executing it.

Nevertheless, whatever quality of implementation compile/eval/exec offer,
they *must* be available at runtime, otherwise the language is just a
subset of Python.



-- 
Steven



From leonardmesiera at gmail.com  Wed Nov 11 07:38:02 2015
From: leonardmesiera at gmail.com (Leonard Andrew Mesiera)
Date: Wed, 11 Nov 2015 20:38:02 +0800
Subject: Guide in Deskop Application Development in Python for newbies
In-Reply-To: <CAMw+j7JLN2PNU4rsK7122WZTAiPUxTac-1fHNvymQ=4Ec3s6Nw@mail.gmail.com>
References: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
 <563E1C95.7030609@gmail.com>
 <CAJ4+4aqbUbHx1vH2ypotXBd_G7LUHG2vjuGH2_Teg1rC6a1M6g@mail.gmail.com>
 <563EAA68.6080906@gmail.com>
 <CAMw+j7JLN2PNU4rsK7122WZTAiPUxTac-1fHNvymQ=4Ec3s6Nw@mail.gmail.com>
Message-ID: <CAJL51tJ_1bpdOXsYDpahnzDD5vd6RMc4ME5Hob+TE9nrNZmMSw@mail.gmail.com>

Thank you sir @Chris Warrick for your great suggestion, even though I
really got overwhelmed by the things that I need to study to get this
project done. I'm really new to programming  so I havent heard or even
tried DJANGO, but on your suggestion, if thats what I need to get my
project done, that would I do. It would really take alot of time for me to
finish this project, but thank you man, I really appreciate your help

On Sun, Nov 8, 2015 at 5:22 PM, Chris Warrick <kwpolska at gmail.com> wrote:

> On 7 November 2015 at 15:44,  <leonardmesiera at gmail.com> wrote:
> > How do you start building a desktop application in python? I mean where
> do I start? Besides installing python on your windows what else do I need,
> and any suggestion on how do I accomplish this project.
> >
> > Right now I really want to finish this beauty pageant judging system
> which requires to have a client and a server, client would be for the
> judges and a server that computes the scores from all the categories, (i do
> hope you get I want mean by that project). I just finished reading
> Headfirst Python and I really loving this language, so any help from all
> the great programmers here would be so great.
> > --
> > https://mail.python.org/mailman/listinfo/python-list
>
> This project requires two very different components, or one monolithic
> server.
>
> The first one is the server. It basically needs to talk to clients
> (via HTTP) and to a database. This is a trivial app to write in your
> favorite web framework, eg. Django [0]. Come up with a good database
> structure (read the excellent tutorial and documentation, should get
> you there), write some models. But you can?t write your views just
> yet. Because the views you write depend strictly on the client.
>
> For the client, you basically have two choices:
> (a) write a web application in Django;
> (b) use a GUI framework and make a standalone desktop application.
>
> If you choose option (a), you need to learn HTML/CSS and write the
> views for your Django application (or use a ready-made front-end
> framework, eg. Bootstrap [1]). This is the simplest choice, and it
> takes a lot of work away from you. Your users will use their favorite
> web browser to access the voting system, log in, and make their votes,
> and there is no special setup for them (apart from giving them
> credentials to access your app). Your Django views will use the
> built-in Django templating, forms, and is relatively simple to do
> (might even be doable in a weekend).
>
> Route (b) is much more complicated. To follow this route, you need to
> pick a GUI framework. There are also multiple options, I personally
> recommend PySide, but you could also try wxWidgets, pygobject or kivy.
> The web app side of things will require serializing data to JSON and
> writing a RESTful API, but there are ready-made solutions for many web
> frameworks [2].
> But most of those come with a catch: they usually make you produce
> ugly code, because they are wrappers around ugly C++ APIs. And then
> you need to write code to talk to your HTTP server. You can?t use the
> beautiful requests library, because it will block ? so there?s more
> work ahead, unless you want your app to be unresponsive every time you
> talk to the server. For example, in Qt, you would need to use Qt
> networking capabilities (which work asynchronously within the event
> loop), or some other implementation that you can use asynchronously
> (eg. Twisted, but then you lock yourself to Python 2, which is bad, or
> threading, which has its limitations?)
> And then you need to distribute your app to your users. Which is
> already hard, because you need to coordinate Python, your GUI
> framework, and your app. Are your users on Windows, Linux, or OS X? If
> you have at least one person on a platform, you will need some sort of
> testing environment?
>
> And no matter which route you choose, you can?t do much without a
> Linux server, so there?s more learning to do.
>
> Sadly, developing big things is hard and requires a lot of knowledge ?
> especially if you?re a one-man-band.
> Here?s a short list of skills you need, with a subjectively suggested
> implementation and ease of implementation:
>
> * understanding of the HTTP protocol (*)
> * web application development (Django *)
> * database schema writing (planning out the structure + Django ORM **)
> * app server setup (uWSGI + nginx + Linux ***)
> * database setup (PostgreSQL *** or something simpler[3])
> * Route A:
>   * HTML/CSS skills; a front-end framework (Bootstrap **)
> * Route B:
>   * RESTful APIs (Django REST Framework ***/***** if you use OAuth)
>   * GUI framework (PyQt ****)
>   * talking to your server from within the framework (****/*****)
>
> [0]: https://www.djangoproject.com/
> [1]: http://getbootstrap.com/
> [2]: http://www.django-rest-framework.org/
> [3]: If this is going to be VERY small, you could go with a sqlite
> database, which requires zero setup, but which is not suited for
> anything more serious.
>
> Other learning materials:
>
>
> https://uwsgi-docs.readthedocs.org/en/latest/tutorials/Django_and_nginx.html
> http://www.fullstackpython.com/
> http://deploypython.com/
>
> On 8 November 2015 at 02:50, Michael Torrie <torriem at gmail.com> wrote:
> > On 11/07/2015 12:15 PM, paul.hermeneutic at gmail.com wrote:
> >> Where would you say that web2py <http://www.web2py.com/> fits into
> this mix
> >> of tools?
> >
> > I am not familiar with it but I know it's supposed to be a lightweight
> > framework for developing web-based sites and applications.  Could be an
> > excellent tool for the OP to use to build his user interface.
> >
> > --
> > https://mail.python.org/mailman/listinfo/python-list
>
> web2py is weird, Django is more fun.
>
> --
> Chris Warrick <https://chriswarrick.com/>
> PGP: 5EAAEA16
>


From leonardmesiera at gmail.com  Wed Nov 11 07:39:40 2015
From: leonardmesiera at gmail.com (Leonard Andrew Mesiera)
Date: Wed, 11 Nov 2015 20:39:40 +0800
Subject: Guide in Deskop Application Development in Python for newbies
In-Reply-To: <CAJL51tJ_1bpdOXsYDpahnzDD5vd6RMc4ME5Hob+TE9nrNZmMSw@mail.gmail.com>
References: <436bfe7e-ece3-454d-b0c7-81de0fe82acb@googlegroups.com>
 <563E1C95.7030609@gmail.com>
 <CAJ4+4aqbUbHx1vH2ypotXBd_G7LUHG2vjuGH2_Teg1rC6a1M6g@mail.gmail.com>
 <563EAA68.6080906@gmail.com>
 <CAMw+j7JLN2PNU4rsK7122WZTAiPUxTac-1fHNvymQ=4Ec3s6Nw@mail.gmail.com>
 <CAJL51tJ_1bpdOXsYDpahnzDD5vd6RMc4ME5Hob+TE9nrNZmMSw@mail.gmail.com>
Message-ID: <CAJL51t+NqHvvTmXtYREovvn9V24txMPdvzXtZcZ3_Fa7OFzLCw@mail.gmail.com>

Thank you sir @Chris Warrick for your great suggestion, even though I
really got overwhelmed by the things that I need to study to get this
project done. I'm really new to programming  so I havent heard or even
tried DJANGO, but on your suggestion, if thats what I need to get my
project done, that would I do. It would really take alot of time for me to
finish this project, but thank you man, I really appreciate your help

On Wed, Nov 11, 2015 at 8:38 PM, Leonard Andrew Mesiera <
leonardmesiera at gmail.com> wrote:

> Thank you sir @Chris Warrick for your great suggestion, even though I
> really got overwhelmed by the things that I need to study to get this
> project done. I'm really new to programming  so I havent heard or even
> tried DJANGO, but on your suggestion, if thats what I need to get my
> project done, that would I do. It would really take alot of time for me to
> finish this project, but thank you man, I really appreciate your help
>
>
> On Sun, Nov 8, 2015 at 5:22 PM, Chris Warrick <kwpolska at gmail.com> wrote:
>
>> On 7 November 2015 at 15:44,  <leonardmesiera at gmail.com> wrote:
>> > How do you start building a desktop application in python? I mean where
>> do I start? Besides installing python on your windows what else do I need,
>> and any suggestion on how do I accomplish this project.
>> >
>> > Right now I really want to finish this beauty pageant judging system
>> which requires to have a client and a server, client would be for the
>> judges and a server that computes the scores from all the categories, (i do
>> hope you get I want mean by that project). I just finished reading
>> Headfirst Python and I really loving this language, so any help from all
>> the great programmers here would be so great.
>> > --
>> > https://mail.python.org/mailman/listinfo/python-list
>>
>> This project requires two very different components, or one monolithic
>> server.
>>
>> The first one is the server. It basically needs to talk to clients
>> (via HTTP) and to a database. This is a trivial app to write in your
>> favorite web framework, eg. Django [0]. Come up with a good database
>> structure (read the excellent tutorial and documentation, should get
>> you there), write some models. But you can?t write your views just
>> yet. Because the views you write depend strictly on the client.
>>
>> For the client, you basically have two choices:
>> (a) write a web application in Django;
>> (b) use a GUI framework and make a standalone desktop application.
>>
>> If you choose option (a), you need to learn HTML/CSS and write the
>> views for your Django application (or use a ready-made front-end
>> framework, eg. Bootstrap [1]). This is the simplest choice, and it
>> takes a lot of work away from you. Your users will use their favorite
>> web browser to access the voting system, log in, and make their votes,
>> and there is no special setup for them (apart from giving them
>> credentials to access your app). Your Django views will use the
>> built-in Django templating, forms, and is relatively simple to do
>> (might even be doable in a weekend).
>>
>> Route (b) is much more complicated. To follow this route, you need to
>> pick a GUI framework. There are also multiple options, I personally
>> recommend PySide, but you could also try wxWidgets, pygobject or kivy.
>> The web app side of things will require serializing data to JSON and
>> writing a RESTful API, but there are ready-made solutions for many web
>> frameworks [2].
>> But most of those come with a catch: they usually make you produce
>> ugly code, because they are wrappers around ugly C++ APIs. And then
>> you need to write code to talk to your HTTP server. You can?t use the
>> beautiful requests library, because it will block ? so there?s more
>> work ahead, unless you want your app to be unresponsive every time you
>> talk to the server. For example, in Qt, you would need to use Qt
>> networking capabilities (which work asynchronously within the event
>> loop), or some other implementation that you can use asynchronously
>> (eg. Twisted, but then you lock yourself to Python 2, which is bad, or
>> threading, which has its limitations?)
>> And then you need to distribute your app to your users. Which is
>> already hard, because you need to coordinate Python, your GUI
>> framework, and your app. Are your users on Windows, Linux, or OS X? If
>> you have at least one person on a platform, you will need some sort of
>> testing environment?
>>
>> And no matter which route you choose, you can?t do much without a
>> Linux server, so there?s more learning to do.
>>
>> Sadly, developing big things is hard and requires a lot of knowledge ?
>> especially if you?re a one-man-band.
>> Here?s a short list of skills you need, with a subjectively suggested
>> implementation and ease of implementation:
>>
>> * understanding of the HTTP protocol (*)
>> * web application development (Django *)
>> * database schema writing (planning out the structure + Django ORM **)
>> * app server setup (uWSGI + nginx + Linux ***)
>> * database setup (PostgreSQL *** or something simpler[3])
>> * Route A:
>>   * HTML/CSS skills; a front-end framework (Bootstrap **)
>> * Route B:
>>   * RESTful APIs (Django REST Framework ***/***** if you use OAuth)
>>   * GUI framework (PyQt ****)
>>   * talking to your server from within the framework (****/*****)
>>
>> [0]: https://www.djangoproject.com/
>> [1]: http://getbootstrap.com/
>> [2]: http://www.django-rest-framework.org/
>> [3]: If this is going to be VERY small, you could go with a sqlite
>> database, which requires zero setup, but which is not suited for
>> anything more serious.
>>
>> Other learning materials:
>>
>>
>> https://uwsgi-docs.readthedocs.org/en/latest/tutorials/Django_and_nginx.html
>> http://www.fullstackpython.com/
>> http://deploypython.com/
>>
>> On 8 November 2015 at 02:50, Michael Torrie <torriem at gmail.com> wrote:
>> > On 11/07/2015 12:15 PM, paul.hermeneutic at gmail.com wrote:
>> >> Where would you say that web2py <http://www.web2py.com/> fits into
>> this mix
>> >> of tools?
>> >
>> > I am not familiar with it but I know it's supposed to be a lightweight
>> > framework for developing web-based sites and applications.  Could be an
>> > excellent tool for the OP to use to build his user interface.
>> >
>> > --
>> > https://mail.python.org/mailman/listinfo/python-list
>>
>> web2py is weird, Django is more fun.
>>
>> --
>> Chris Warrick <https://chriswarrick.com/>
>> PGP: 5EAAEA16
>>
>
>


From rosuav at gmail.com  Wed Nov 11 08:13:29 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 12 Nov 2015 00:13:29 +1100
Subject: Python.exe is not a valid Win32 application error message
In-Reply-To: <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
Message-ID: <CAPTjJmpOYrpHzsFmBigF=wHEmVGp=SOpk9LsSF11=C-c4KH+6g@mail.gmail.com>

On Tue, Nov 10, 2015 at 11:34 AM, M. Kamisato via Python-list
<python-list at python.org> wrote:
> I am running python on Windows XP SP3 and download version 3.5xx.  I got the above error message and could not run the program.
> I have downloaded Python version 2.7xx and it runs fine.
> Is there any way I can get version 3.5xx to run on my computer?
> Mel KamisatoBuena Park, CA

You can't get 3.5 to run on XP, no; your options are:

1) Install Python 3.4, which does support XP
2) Upgrade to a newer version of Windows (anything from Vista onward
will run 3.5; to save having to do this in future, jump straight to 7
or 10)
3) Make the jump to Linux or FreeBSD or some other OS.

When 3.5.1 is released (currently scheduled for early December),
you'll get a clear and simple error when you try to install, rather
than strange issues about it not being a valid program. That won't
change the platform support, but at least it won't be as confusing.

ChrisA


From torriem at gmail.com  Wed Nov 11 10:28:11 2015
From: torriem at gmail.com (Michael Torrie)
Date: Wed, 11 Nov 2015 08:28:11 -0700
Subject: Python.exe is not a valid Win32 application error message
In-Reply-To: <CAPTjJmpOYrpHzsFmBigF=wHEmVGp=SOpk9LsSF11=C-c4KH+6g@mail.gmail.com>
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
 <CAPTjJmpOYrpHzsFmBigF=wHEmVGp=SOpk9LsSF11=C-c4KH+6g@mail.gmail.com>
Message-ID: <56435E8B.10103@gmail.com>

On 11/11/2015 06:13 AM, Chris Angelico wrote:
> On Tue, Nov 10, 2015 at 11:34 AM, M. Kamisato via Python-list
> <python-list at python.org> wrote:
>> I am running python on Windows XP SP3 and download version 3.5xx.  I got the above error message and could not run the program.
>> I have downloaded Python version 2.7xx and it runs fine.
>> Is there any way I can get version 3.5xx to run on my computer?
>> Mel KamisatoBuena Park, CA
> 
> You can't get 3.5 to run on XP, no; your options are:
> 
> 1) Install Python 3.4, which does support XP
> 2) Upgrade to a newer version of Windows (anything from Vista onward
> will run 3.5; to save having to do this in future, jump straight to 7
> or 10)
> 3) Make the jump to Linux or FreeBSD or some other OS.
> 
> When 3.5.1 is released (currently scheduled for early December),
> you'll get a clear and simple error when you try to install, rather
> than strange issues about it not being a valid program. That won't
> change the platform support, but at least it won't be as confusing.

The Python website is looking very professional and polished these days.
 But we still don't have a simple message on the download page telling
people Windows XP is no longer supported.  Given the number of people
posting lately (several each week), I would think even with the limited
time and resources of the python.org webmaster a little warning message
would be in order.  Even when the installer is fixed, it would still be
nice to have basic OS requirements listed before the download is ever
clicked.


From framstag at rus.uni-stuttgart.de  Wed Nov 11 11:16:35 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 11 Nov 2015 16:16:35 +0000 (UTC)
Subject: cross platform alternative for signal.SIGALRM?
Message-ID: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>

I am rewriting a Perl program into Python (2.7).
It must run on Linux and Windows.
With Linux I have no problems, but Windows... :-(

The current show stopper is signal.SIGALRM which is not available on
Windows:

  File "fexit.py", line 674, in formdata_post
    signal.signal(signal.SIGALRM,timeout_handler)
  AttributeError: 'module' object has no attribute 'SIGALRM'


  https://docs.python.org/2/library/signal.html

  signal.alarm(time) (...) Availability: Unix.

Perl for Windows has had SIGALRM support (or some kind of emulation).

Ok, I have to redesign this part of my code:

  def timeout_handler(sig,frame): 
    raise ValueError("timeout!")
    
  signal.signal(signal.SIGALRM,timeout_handler)

  while True:
    chunk = fileo.read(bs)
    sock.sendall(chunk)
    (...)


What is the best practise for a cross platform timeout handler?




-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From tim at akwebsoft.com  Wed Nov 11 11:16:57 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Wed, 11 Nov 2015 07:16:57 -0900
Subject: Using subprocess to capture a progress line
In-Reply-To: <CAMw+j7LZH44RnPXgP4XVDiv62uJ_iFmsEm17QpsmNBSDr=uvJw@mail.gmail.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAMw+j7LZH44RnPXgP4XVDiv62uJ_iFmsEm17QpsmNBSDr=uvJw@mail.gmail.com>
Message-ID: <20151111161657.GE1944@mail.akwebsoft.com>

* Chris Warrick <kwpolska at gmail.com> [151111 00:55]:
> On 10 November 2015 at 23:47, Tim Johnson <tim at akwebsoft.com> wrote:
> > Using python 2.7.6 on ubuntu 14.04
<..> 
> There is no \n character at the end ? which means that
> p.stdout.readline() cannot return. In fact, if you printed repr() of
> the line you read, you would get this:
> 
> b'\r[download]  54.9% of 2.73MiB at 26.73KiB/s ETA 00:47\r[download]
> 55.0% of 2.73MiB at 79.33KiB/s ETA 00:15\r?snip?\r[download] 100% of
> 2.73MiB in 00:01\n'
> 
> The download line is implemented using \r, which is the carriage
> return character (return to the first character), and then by
> overwriting characters that were already printed.
> 
> The solution? There are numerous. I?ll help you by obscuring the worst one.
> 
> (1) [recommended] figure out how to make youtube_dl work as a library,
> read its main file to figure out the problem. Don?t mess with
> subprocess.
  Was my first goal, had some problems, but I have solved them in
  part by finding the good documentation of the developers.

  I.E., the subprocess method _is_ going away and I will be using
  the youtube_dl module.

> (2) [don?t do it] do you need to intercept the lines? If you don?t set
> stderr= and stdout=, things will print just fine.
  Got to try that before using the module, just for edification.

> (3) [DON?T DO IT] .ernq() punenpgre ol punenpgre naq znxr n zrff.
> 
> PS. Thank you for setting a sensible Reply-To header on your messages.
> Which is something the list should be doing.
  LOL! Glad to help :)
  Thanks for the reply and the further education. 
  Cheers
-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From marko at pacujo.net  Wed Nov 11 11:30:23 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 11 Nov 2015 18:30:23 +0200
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
Message-ID: <87si4cts68.fsf@elektro.pacujo.net>

Ulli Horlacher <framstag at rus.uni-stuttgart.de>:

> What is the best practise for a cross platform timeout handler?

Here's the simplest answer:

   https://docs.python.org/3/library/threading.html#threading.Timer

(Also available in Python 2.)


Marko


From anas.belemlih at gmail.com  Wed Nov 11 11:34:30 2015
From: anas.belemlih at gmail.com (Anas Belemlih)
Date: Wed, 11 Nov 2015 08:34:30 -0800 (PST)
Subject: new to python, help please !!
Message-ID: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>

i am  a beginning programmer,  i am trying to write a simple code to compare two character sets in 2 seperate files. ( 2 hash value files basically)
idea is:
 open both files, measure the length of the  loop on.

if the length doesn't match, ==  files do not  match

if length matchs, loop  while comparing each character from each file if they match. 
 please tell me what i am doing wrong ?  i am using python 2.7

**********************************
hash1= open ("file1.md5", "r")
line1 =hash1.read()
hash2 = open("file2.md5","r")
line2= hash2.read()

number1 = len(line1)
number2 = len(line2)

#**************************
i=0
s1=line1[i]
s2=line2[i]
count = 0

if number1 != number2:
	print " hash table not the same size"
else:
    while count < number1:
	if s1 == s2:
		print " character", line1[i]," matchs"
		i=i+1
	count=count+1
	else
		print "Hash values corrupt"


From kwpolska at gmail.com  Wed Nov 11 11:48:56 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Wed, 11 Nov 2015 17:48:56 +0100
Subject: Using subprocess to capture a progress line
In-Reply-To: <20151111161657.GE1944@mail.akwebsoft.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAMw+j7LZH44RnPXgP4XVDiv62uJ_iFmsEm17QpsmNBSDr=uvJw@mail.gmail.com>
 <20151111161657.GE1944@mail.akwebsoft.com>
Message-ID: <CAMw+j7K2V3xQX-cncfgJgxf9CsODe-Y2hS_A6ZTy7m45P6MVcw@mail.gmail.com>

On 11 November 2015 at 17:16, Tim Johnson <tim at akwebsoft.com> wrote:
>> (2) [don?t do it] do you need to intercept the lines? If you don?t set
>> stderr= and stdout=, things will print just fine.
>   Got to try that before using the module, just for edification.

At which point your initial code sample will become:
###########
    p = subprocess.Popen(list(args))
###########

(is list(args) really necessary? Wouldn?t plain Popen(args) just work?)

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From gordon at panix.com  Wed Nov 11 11:58:22 2015
From: gordon at panix.com (John Gordon)
Date: Wed, 11 Nov 2015 16:58:22 +0000 (UTC)
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
Message-ID: <n1vs3e$6ih$1@reader1.panix.com>

In <93aef8e5-3d6f-41f4-a625-cd3c2007686e at googlegroups.com> Anas Belemlih <anas.belemlih at gmail.com> writes:

> i=0
> s1=line1[i]
> s2=line2[i]
> count = 0

> if number1 != number2:
> 	print " hash table not the same size"
> else:
>     while count < number1:
> 	if s1 == s2:
> 		print " character", line1[i]," matchs"
> 		i=i+1
> 	count=count+1
> 	else
> 		print "Hash values corrupt"

It looks like you're expecting s1 and s2 to automatically update their
values when i gets incremented, but it doesn't work like that.  When you
increment i, you also have to reassign s1 and s2.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From framstag at rus.uni-stuttgart.de  Wed Nov 11 12:06:46 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 11 Nov 2015 17:06:46 +0000 (UTC)
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <87si4cts68.fsf@elektro.pacujo.net>
Message-ID: <n1vsj6$ijf$1@news2.informatik.uni-stuttgart.de>

Marko Rauhamaa <marko at pacujo.net> wrote:
> Ulli Horlacher <framstag at rus.uni-stuttgart.de>:
> 
> > What is the best practise for a cross platform timeout handler?
> 
> Here's the simplest answer:
> 
>    https://docs.python.org/3/library/threading.html#threading.Timer
> 
> (Also available in Python 2.)

Hmmm... not so simple for me. My test code:

from time import *
import threading
import sys

def hello(): 
raise ValueError("hello!!!")

t = threading.Timer(3.0,hello)
t.start()
try:
  print "start"
  sleep(5)
  print "end"
except ValueError as e:
  print e.args[0]
  sys.exit(1)


gives:


start
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 759, in run
    self.function(*self.args, **self.kwargs)
  File "x.py", line 7, in hello
    def hello(): raise ValueError("hello!!!")
ValueError: hello!!!

end



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From python.list at tim.thechases.com  Wed Nov 11 12:06:55 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Wed, 11 Nov 2015 11:06:55 -0600
Subject: new to python, help please !!
In-Reply-To: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
Message-ID: <20151111110655.7293d3b7@bigbox.christie.dr>

On 2015-11-11 08:34, Anas Belemlih wrote:
> i am  a beginning programmer,  i am trying to write a simple code
> to compare two character sets in 2 seperate files. ( 2 hash value
> files basically) idea is: open both files, measure the length of
> the  loop on.
> 
> if the length doesn't match, ==  files do not  match
> 
> if length matchs, loop  while comparing each character from each
> file if they match. please tell me what i am doing wrong ?  i am
> using python 2.7
> 
> **********************************
> hash1= open ("file1.md5", "r")
> line1 =hash1.read()
> hash2 = open("file2.md5","r")
> line2= hash2.read()
> 
> number1 = len(line1)
> number2 = len(line2)
> 
> #**************************
> i=0
> s1=line1[i]
> s2=line2[i]
> count = 0
> 
> if number1 != number2:
> 	print " hash table not the same size"
> else:
>     while count < number1:
> 	if s1 == s2:
> 		print " character", line1[i]," matchs"
> 		i=i+1
> 	count=count+1
> 	else
> 		print "Hash values corrupt"

Well, the immediate answer is that you don't update s1 or s2 inside
your loop.  Also, the indent on "count=count+1" is wrong.  Finally,
if the hashes don't match, you don't break out of your while loop.
That said, the pythonesque way of writing this would likely look
something much more like

  with open("file1.md5") as a, open("file2.md5") as b:
    for s1, s2 in zip(a, b):
      if s1 != s2:
        print("Files differ")

You can compare the strings to get the actual offset if you want, or
check the lengths if you really want a more verbatim translation of
your code:

  with open("file1.md5") as a, open("file2.md5") as b:
    for s1, s2 in zip(a, b):
      if len(s1) != len(s2):
        print("not the same size")
      else:
        for i, (c1, c2) in enumerate(zip(s1, s2)):
          if c1 == c2:
            print(" character %s matches" %  c1)
          else:
            print(" %r and %r differ at position %i" % (s1, s2, i))

-tkc





From ben+python at benfinney.id.au  Wed Nov 11 12:16:21 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 12 Nov 2015 04:16:21 +1100
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
Message-ID: <85pozge9sq.fsf@benfinney.id.au>

Anas Belemlih <anas.belemlih at gmail.com> writes:

> i am  a beginning programmer,  i am trying to write a simple code to
> compare two character sets in 2 seperate files. ( 2 hash value files
> basically)

Welcome, and congratulations on arriving at Python for your programming!

As a beginning programmer, you will benefit from joining the ?tutor?
forum <URL:https://mail.python.org/mailman/listinfo/tutor>, which is
much better suited to collaborative teaching of newcomers.

-- 
 \     ?As scarce as truth is, the supply has always been in excess of |
  `\                                       the demand.? ?Josh Billings |
_o__)                                                                  |
Ben Finney



From torriem at gmail.com  Wed Nov 11 12:31:06 2015
From: torriem at gmail.com (Michael Torrie)
Date: Wed, 11 Nov 2015 10:31:06 -0700
Subject: Python.exe is not a valid Win32 application error message
In-Reply-To: <sOK0y.222868$6i2.161614@fx35.am4>
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <mailman.237.1447247021.16136.python-list@python.org>
 <sOK0y.222868$6i2.161614@fx35.am4>
Message-ID: <56437B5A.6080802@gmail.com>

On 11/11/2015 10:21 AM, Quivis wrote:
> On Tue, 10 Nov 2015 00:34:23 +0000, M. Kamisato wrote:
> 
>> I am running python on Windows XP SP3 and download version 3.5xx.  I got
>> the above error message and could not run the program.
>> I have downloaded Python version 2.7xx and it runs fine.
>> Is there any way I can get version 3.5xx to run on my computer?
>> Mel KamisatoBuena Park, CA
> 
> 
> Did you DL the 64-bit version...?

In this case, it would not matter; Windows XP is simply too old to run
Python 3.5, but the web page neglects to mention that, and the installer
does not yet warn the user, though it will in the next minor version
release.



From cameron.houliston at hotmail.com  Wed Nov 11 12:35:45 2015
From: cameron.houliston at hotmail.com (Cameron Houliston)
Date: Wed, 11 Nov 2015 17:35:45 +0000
Subject: Hi
Message-ID: <SNT406-EAS1698A9EEF273B68B87176EFE9130@phx.gbl>

Can I have a link to use python

Sent from Mail for Windows 10


From marko at pacujo.net  Wed Nov 11 13:03:12 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 11 Nov 2015 20:03:12 +0200
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <87si4cts68.fsf@elektro.pacujo.net>
 <n1vsj6$ijf$1@news2.informatik.uni-stuttgart.de>
Message-ID: <87oaf0tnvj.fsf@elektro.pacujo.net>

Ulli Horlacher <framstag at rus.uni-stuttgart.de>:

> Hmmm... not so simple for me. My test code:
>
> from time import *
> import threading
> import sys
>
> def hello(): 
> raise ValueError("hello!!!")
>
> t = threading.Timer(3.0,hello)
> t.start()
> try:
>   print "start"
>   sleep(5)
>   print "end"
> except ValueError as e:
>   print e.args[0]
>   sys.exit(1)

Correct. The timer callback function (hello) would be called in a
separate thread. An exception raised in one thread cannot be caught in
the main thread. In general, there is no way for a thread to interrupt a
sibling thread that is in a blocking function call.


Marko


From tim at akwebsoft.com  Wed Nov 11 13:52:19 2015
From: tim at akwebsoft.com (Tim Johnson)
Date: Wed, 11 Nov 2015 09:52:19 -0900
Subject: Using subprocess to capture a progress line
In-Reply-To: <CAMw+j7K2V3xQX-cncfgJgxf9CsODe-Y2hS_A6ZTy7m45P6MVcw@mail.gmail.com>
References: <20151110224756.GA1944@mail.akwebsoft.com>
 <CAMw+j7LZH44RnPXgP4XVDiv62uJ_iFmsEm17QpsmNBSDr=uvJw@mail.gmail.com>
 <20151111161657.GE1944@mail.akwebsoft.com>
 <CAMw+j7K2V3xQX-cncfgJgxf9CsODe-Y2hS_A6ZTy7m45P6MVcw@mail.gmail.com>
Message-ID: <20151111185219.GF1944@mail.akwebsoft.com>

* Chris Warrick <kwpolska at gmail.com> [151111 07:54]:
> On 11 November 2015 at 17:16, Tim Johnson <tim at akwebsoft.com> wrote:
> >> (2) [don?t do it] do you need to intercept the lines? If you don?t set
> >> stderr= and stdout=, things will print just fine.
> >   Got to try that before using the module, just for edification.
> 
> At which point your initial code sample will become:
> ###########
>     p = subprocess.Popen(list(args))
> ###########
> 
  Yeah, 'list is redundant.
  Progress is now showing, but I forgot to say that I've lost the
  original intent, and that was to examine each line so that I could
  pull out the title.

  No matter. I'm on the way to make the youtube_dl module working.
  cheers

-- 
Tim 
http://www.akwebsoft.com, http://www.tj49.com


From kaifmahmood2000 at hotmail.co.uk  Wed Nov 11 15:01:46 2015
From: kaifmahmood2000 at hotmail.co.uk (Kaif Mahmood)
Date: Wed, 11 Nov 2015 20:01:46 +0000
Subject: =?utf-8?Q?Python_Trouble?=
Message-ID: <DUB405-EAS254A6E4B3C370A303ECF884F8130@phx.gbl>

I downloaded the recent version of Python and after it downloaded I tried IDLE. But when I tried to load it, it didn?t load and just acted as if nothing happened. All of the other features work fine, it?s just IDLE not working. I tried different versions but I encounter the same problem. The only way I managed to load it was by right clicking on previous files and clicking edit with IDLE; IDLE loaded but when I clicked run, it just froze and closed. Please help.






Sent from Windows Mail

From auriocus at gmx.de  Wed Nov 11 16:32:18 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 11 Nov 2015 22:32:18 +0100
Subject: using binary in python
In-Reply-To: <mailman.218.1447190949.16136.python-list@python.org>
References: <mailman.164.1447060794.16136.python-list@python.org>
 <HbGdndTOtKc3EdzLnZ2dnUU7-YnOydjZ@giganews.com>
 <mailman.218.1447190949.16136.python-list@python.org>
Message-ID: <n20c0p$c0o$1@dont-email.me>

Am 10.11.15 um 22:29 schrieb kent nyberg:
> On Mon, Nov 09, 2015 at 10:20:25PM -0800, Larry Hudson via Python-list wrote:
>> Your questions are somewhat difficult to answer because you misunderstand
>> binary.  The key is that EVERYTHING in a computer is binary.  There are NO
>> EXCEPTIONS, it's all binary ALL the time.  The difference comes about in how
>> this binary data is displayed and manipulated.  I want to emphasize, ALL the
>> DATA is binary.
>>
>
> Thanks alot for taking the time.
> I get it now. I sort of, but not fully, misunderstood the conecpt of binary files.
> The thing I was after; and the thing Im playing with now after a more succesfull time with google,
> is writing more specific things to a file than just strings.
> English is not my native language so please forgive me, but
> I wanted to write specifc 16bit codes, and read them. And later play with bitwise operations on them. Sort of.
> It might not make sense at all, but hey..  it doesnt have to

I think I understand what you want. Look at the struct module:

https://docs.python.org/2/library/struct.html

You can write/read binary data from files with standard means. Using 
struct, you can interpret or format integer values into a specific 
binary format. That would allow to create a reader or writer for a given 
binary format in Python.

	Christian




From framstag at rus.uni-stuttgart.de  Wed Nov 11 17:42:28 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 11 Nov 2015 22:42:28 +0000 (UTC)
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <87si4cts68.fsf@elektro.pacujo.net>
 <n1vsj6$ijf$1@news2.informatik.uni-stuttgart.de>
 <87oaf0tnvj.fsf@elektro.pacujo.net>
Message-ID: <n20g8k$o9h$1@news2.informatik.uni-stuttgart.de>

Marko Rauhamaa <marko at pacujo.net> wrote:

> Correct. The timer callback function (hello) would be called in a
> separate thread. An exception raised in one thread cannot be caught in
> the main thread. In general, there is no way for a thread to interrupt a
> sibling thread that is in a blocking function call.

Then threading.Timer is not a solution for my problem.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From tjreedy at udel.edu  Wed Nov 11 20:37:34 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 11 Nov 2015 20:37:34 -0500
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n20qh1$alv$1@ger.gmane.org>

On 11/11/2015 11:16 AM, Ulli Horlacher wrote:
> I am rewriting a Perl program into Python (2.7).

I recommend using 3.4+ if you possibly can.

> It must run on Linux and Windows.
> With Linux I have no problems, but Windows... :-(
>
> The current show stopper is signal.SIGALRM which is not available on
> Windows:

> Perl for Windows has had SIGALRM support (or some kind of emulation).
>
> Ok, I have to redesign this part of my code:
>
>    def timeout_handler(sig,frame):
>      raise ValueError("timeout!")
>
>    signal.signal(signal.SIGALRM,timeout_handler)
>
>    while True:
>      chunk = fileo.read(bs)
>      sock.sendall(chunk)
>      (...)
>
> What is the best practise for a cross platform timeout handler?

The cross-platform 3.4 asyncio module has some functions with timeouts.
(3.5 has new 'async' syntac which supposedly makes it easier to use.  I 
have not looked at this yet.)

For instance: coroutine asyncio.wait(futures, *, loop=None, 
timeout=None, return_when=ALL_COMPLETED)
     Wait for the Futures and coroutine objects given by the sequence 
futures to complete. Coroutines will be wrapped in Tasks. Returns two 
sets of Future: (done, pending).
...
Usage:
   done, pending = yield from asyncio.wait(fs)

I believe the backport on pypi.python.org, called tulip, works on 2.7.

In the example above, the read/send would be a task.  Wait on the task, 
and when it returns, cancel the task if in pending.


-- 
Terry Jan Reedy



From tundraBOGUS at tundraware.com  Wed Nov 11 20:52:38 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Wed, 11 Nov 2015 19:52:38 -0600
Subject: More tkinter Madness
Message-ID: <708dhc-3pf1.ln1@oceanview.tundraware.com>

I am the author of twander (https://www.tundraware.com/Software/twander).
This code has run flawlessly for years on FreeBSD, Linux, MacOS and
Windows.  Some months ago, I put it on a couple of VPS servers (FreeBSD
and Linux) and BOOM, it doesn't run.  I asked around here and got some
suggestions and then did some homework.

I see the error being thrown by using the trace module, but it's not 
terribly meaningful to me.  Any ideas of what this means - again,
I emphasize this is only happening on VPS hosts:

 --- modulename: Tkinter, funcname: _cnfmerge
Tkinter.py(76):     if type(cnfs) is DictionaryType:
Tkinter.py(77):         return cnfs
Tkinter.py(1046):         res = ()
Tkinter.py(1047):         for k, v in cnf.items():
Tkinter.py(1048):             if v is not None:
Tkinter.py(1049):                 if k[-1] == '_': k = k[:-1]
Tkinter.py(1050):                 if callable(v):
Tkinter.py(1052):                 elif isinstance(v, (tuple, list)):
Tkinter.py(1064):                 res = res + ('-'+k, v)
Tkinter.py(1047):         for k, v in cnf.items():
Tkinter.py(1048):             if v is not None:
Tkinter.py(1049):                 if k[-1] == '_': k = k[:-1]
Tkinter.py(1050):                 if callable(v):
Tkinter.py(1052):                 elif isinstance(v, (tuple, list)):
Tkinter.py(1064):                 res = res + ('-'+k, v)
Tkinter.py(1047):         for k, v in cnf.items():
Tkinter.py(1048):             if v is not None:
Tkinter.py(1049):                 if k[-1] == '_': k = k[:-1]
Tkinter.py(1050):                 if callable(v):
Tkinter.py(1052):                 elif isinstance(v, (tuple, list)):
Tkinter.py(1064):                 res = res + ('-'+k, v)
Tkinter.py(1047):         for k, v in cnf.items():
Tkinter.py(1065):         return res
Traceback (most recent call last):
  File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib64/python2.6/runpy.py", line 34, in _run_code
    exec code in run_globals
  File "/usr/lib64/python2.6/trace.py", line 823, in <module>
    main()
  File "/usr/lib64/python2.6/trace.py", line 811, in main
    t.runctx(code, globs, globs)
  File "/usr/lib64/python2.6/trace.py", line 512, in runctx
    exec cmd in globals, locals
  File "/local/TundraWare/bin/twander.py", line 5464, in <module>
    UI = twanderUI(UIroot)
  File "/local/TundraWare/bin/twander.py", line 2152, in __init__
    self.CmdBtn = Menubutton(self.mBar, text=COMMANDMENU, underline=0, state=DISABLED)
  File "/usr/lib64/python2.6/lib-tk/Tkinter.py", line 2710, in __init__
    Widget.__init__(self, master, 'menubutton', cnf, kw)
  File "/usr/lib64/python2.6/lib-tk/Tkinter.py", line 1932, in __init__
    (widgetName, self._w) + extra + self._options(cnf))
_tkinter.TclError


From no.email at nospam.invalid  Wed Nov 11 21:12:42 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Wed, 11 Nov 2015 18:12:42 -0800
Subject: More tkinter Madness
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
Message-ID: <87oaf0q82t.fsf@nightsong.com>

Tim Daneliuk <tundraBOGUS at tundraware.com> writes:
> Some months ago, I put it on a couple of VPS servers (FreeBSD
> and Linux) and BOOM, it doesn't run.  I asked around here and got some
> suggestions and then did some homework.

I'd expect a VPS server to have no display--is it an X client forward to
your workstation?  Are all the proper X libraries installed?  Note that
X port forwarding over the internet is generally unusable even if your
internet connection is pretty fast.  It's kind of ok over a LAN.


From rosuav at gmail.com  Wed Nov 11 21:25:56 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 12 Nov 2015 13:25:56 +1100
Subject: More tkinter Madness
In-Reply-To: <708dhc-3pf1.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
Message-ID: <CAPTjJmoQtBw-K8kF-KOYp8VovmOVQ=Ta_9wRHQ3B+OKXghgsvw@mail.gmail.com>

On Thu, Nov 12, 2015 at 12:52 PM, Tim Daneliuk
<tundraBOGUS at tundraware.com> wrote:
> I am the author of twander (https://www.tundraware.com/Software/twander).
> This code has run flawlessly for years on FreeBSD, Linux, MacOS and
> Windows.  Some months ago, I put it on a couple of VPS servers (FreeBSD
> and Linux) and BOOM, it doesn't run.  I asked around here and got some
> suggestions and then did some homework.
>
> Traceback (most recent call last):
>   File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main

It's running here under Python 2.6. Sorry if this is a question you've
already been asked, but were you successfully running under 2.6
elsewhere? Might be a versioning issue.

ChrisA


From steve+comp.lang.python at pearwood.info  Wed Nov 11 21:58:35 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Thu, 12 Nov 2015 13:58:35 +1100
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <obL0y.222880$6i2.63495@fx35.am4>
Message-ID: <5644005e$0$2932$c3e8da3$76491128@news.astraweb.com>

On Thursday 12 November 2015 04:48, Quivis wrote:

> On Wed, 11 Nov 2015 08:34:30 -0800, Anas Belemlih wrote:
> 
>> md5
> 
> If those are md5 values stored inside files, wouldn't it be easier to
> just hash them?
> 
> import hashlib
> 
> m1 = hashlib.sha224(open('f1').read()).hexdigest()
> m2 = hashlib.sha224(open('f2').read()).hexdigest()

I presume that the purpose of the exercise is to learn basic Python skills 
like looping.

Also, using sha224 when all you want is a simple "different"/"equal" is 
horribly inefficient. Sha224 needs to read the entire file, every single 
byte, *and* perform a bunch of expensive cryptographic operations. Consider 
reading two five GB files, the first starting with byte \x30 and the second 
starting with byte \x60. The two bytes are different, so we know the files 
differ, but sha224 still needs to do a massive amount of work.



-- 
Steve



From rxjwg98 at gmail.com  Wed Nov 11 22:04:36 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 11 Nov 2015 19:04:36 -0800 (PST)
Subject: How to get 'od' run?
Message-ID: <24ed2ddb-aaea-455e-bf45-10e1cd8e8376@googlegroups.com>

Hi,

I am learning python. I see a previous post has such code:





   >>> data = '"bin??ridataa"\n'.encode('utf-8') 
   >>> f = open('roska.txt', 'wb') 
   >>> f.write(data) 
   17 
   >>> f.close() 

The .encode methods produced a bytestring, which Python likes to display 
as ASCII characters where it can and in hexadecimal where it cannot: 

   >>> data 
   b'"bin\xc3\xa4\xc3\xa4ridataa"\n' 

An "octal dump" in characters (where ASCII, otherwise apparently octal) 
and the corresponding hexadecimal shows that it is, indeed, these bytes 
that ended up in the file: 

$ od -t cx1 roska.txt 


When I run the above line with python 2.7, it does not recognize 'od'.

Is it from a package? Or some internal function?

Thanks,


From torriem at gmail.com  Wed Nov 11 22:21:08 2015
From: torriem at gmail.com (Michael Torrie)
Date: Wed, 11 Nov 2015 20:21:08 -0700
Subject: How to get 'od' run?
In-Reply-To: <24ed2ddb-aaea-455e-bf45-10e1cd8e8376@googlegroups.com>
References: <24ed2ddb-aaea-455e-bf45-10e1cd8e8376@googlegroups.com>
Message-ID: <564405A4.2060300@gmail.com>

On 11/11/2015 08:04 PM, fl wrote:
> Hi,
> 
> I am learning python. I see a previous post has such code:
> 
> 
> 
> 
> 
>    >>> data = '"bin??ridataa"\n'.encode('utf-8') 
>    >>> f = open('roska.txt', 'wb') 
>    >>> f.write(data) 
>    17 
>    >>> f.close() 
> 
> The .encode methods produced a bytestring, which Python likes to display 
> as ASCII characters where it can and in hexadecimal where it cannot: 
> 
>    >>> data 
>    b'"bin\xc3\xa4\xc3\xa4ridataa"\n' 
> 
> An "octal dump" in characters (where ASCII, otherwise apparently octal) 
> and the corresponding hexadecimal shows that it is, indeed, these bytes 
> that ended up in the file: 
> 
> $ od -t cx1 roska.txt 
 ^^^
This is most likely a bash prompt. Therefore "od" is a program on your
computer.  Nothing to do with Python at all.

To get Python to display \x## hex codes for non-ascii characters in a
byte stream, you can print out the repr() of the byte string.  For example:

print (repr(my_unicode_string.encode('utf-8')))




From torriem at gmail.com  Wed Nov 11 22:34:49 2015
From: torriem at gmail.com (Michael Torrie)
Date: Wed, 11 Nov 2015 20:34:49 -0700
Subject: How to get 'od' run?
In-Reply-To: <564405A4.2060300@gmail.com>
References: <24ed2ddb-aaea-455e-bf45-10e1cd8e8376@googlegroups.com>
 <564405A4.2060300@gmail.com>
Message-ID: <564408D9.5040303@gmail.com>

On 11/11/2015 08:21 PM, Michael Torrie wrote:
> On 11/11/2015 08:04 PM, fl wrote:
>> Hi,
>>
>> I am learning python. I see a previous post has such code:
>>
>>
>>
>>
>>
>>    >>> data = '"bin??ridataa"\n'.encode('utf-8') 
>>    >>> f = open('roska.txt', 'wb') 
>>    >>> f.write(data) 
>>    17 
>>    >>> f.close() 
>>
>> The .encode methods produced a bytestring, which Python likes to display 
>> as ASCII characters where it can and in hexadecimal where it cannot: 
>>
>>    >>> data 
>>    b'"bin\xc3\xa4\xc3\xa4ridataa"\n' 
>>
>> An "octal dump" in characters (where ASCII, otherwise apparently octal) 
>> and the corresponding hexadecimal shows that it is, indeed, these bytes 
>> that ended up in the file: 
>>
>> $ od -t cx1 roska.txt 
>  ^^^
> This is most likely a bash prompt. Therefore "od" is a program on your
> computer.  Nothing to do with Python at all.
> 
> To get Python to display \x## hex codes for non-ascii characters in a
> byte stream, you can print out the repr() of the byte string.  For example:
> 
> print (repr(my_unicode_string.encode('utf-8')))

Also there are numerous recipes for doing standard hex dumps out there.
 For example,

http://code.activestate.com/recipes/142812-hex-dumper/


From hayesstw at telkomsa.net  Wed Nov 11 23:43:44 2015
From: hayesstw at telkomsa.net (Steve Hayes)
Date: Thu, 12 Nov 2015 06:43:44 +0200
Subject: Python.exe is not a valid Win32 application error message
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
 <mailman.241.1447247613.16136.python-list@python.org>
Message-ID: <53684bd0ecp0krft87qlerlkobh8kjp575@4ax.com>

On Thu, 12 Nov 2015 00:13:29 +1100, Chris Angelico <rosuav at gmail.com>
wrote:

>On Tue, Nov 10, 2015 at 11:34 AM, M. Kamisato via Python-list
><python-list at python.org> wrote:
>> I am running python on Windows XP SP3 and download version 3.5xx.  I got the above error message and could not run the program.
>> I have downloaded Python version 2.7xx and it runs fine.
>> Is there any way I can get version 3.5xx to run on my computer?
>> Mel KamisatoBuena Park, CA
>
>You can't get 3.5 to run on XP, no; your options are:
>
>1) Install Python 3.4, which does support XP
>2) Upgrade to a newer version of Windows (anything from Vista onward
>will run 3.5; to save having to do this in future, jump straight to 7
>or 10)
>3) Make the jump to Linux or FreeBSD or some other OS.

That is useful to know. 

I get messages (from Glary Utilities) that some of my programs
(including Python) need to be updated, but when I've downloaded and
updated them, the update hasn't worked. 


-- 
Steve Hayes from Tshwane, South Africa
Web:  http://www.khanya.org.za/stevesig.htm
Blog: http://khanya.wordpress.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk


From hayesstw at telkomsa.net  Wed Nov 11 23:44:38 2015
From: hayesstw at telkomsa.net (Steve Hayes)
Date: Thu, 12 Nov 2015 06:44:38 +0200
Subject: Python.exe is not a valid Win32 application error message
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
 <mailman.242.1447249173.16136.python-list@python.org>
Message-ID: <d8684b11krrlglrtisrjdq75djc7bi2qb5@4ax.com>

On Wed, 11 Nov 2015 08:39:21 -0500, Dennis Lee Bieber
<wlfraed at ix.netcom.com> wrote:

>On Tue, 10 Nov 2015 00:34:23 +0000 (UTC), "M. Kamisato via Python-list"
><python-list at python.org> declaimed the following:
>
>>I am running python on Windows XP SP3 and download version 3.5xx. ?I got the above error message and could not run the program.
>>I have downloaded Python version 2.7xx and it runs fine.
>>Is there any way I can get version 3.5xx to run on my computer?
>>Mel KamisatoBuena Park, CA
>
>	Install Windows Vista, 7, 8.1, or 10.
>
>	Windows XP is not a supported OS for Python 3.5+

Or revert to an earlier version of Python that does work. 


-- 
Steve Hayes from Tshwane, South Africa
Web:  http://www.khanya.org.za/stevesig.htm
Blog: http://khanya.wordpress.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk


From cs at zip.com.au  Thu Nov 12 00:20:46 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Thu, 12 Nov 2015 16:20:46 +1100
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
Message-ID: <20151112052046.GA35372@cskk.homeip.net>

On 11Nov2015 16:16, Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
>I am rewriting a Perl program into Python (2.7).
>It must run on Linux and Windows.
>With Linux I have no problems, but Windows... :-(
>
>The current show stopper is signal.SIGALRM which is not available on
>Windows:
>
>  File "fexit.py", line 674, in formdata_post
>    signal.signal(signal.SIGALRM,timeout_handler)
>  AttributeError: 'module' object has no attribute 'SIGALRM'
>
>  https://docs.python.org/2/library/signal.html
>
>  signal.alarm(time) (...) Availability: Unix.
>
>Perl for Windows has had SIGALRM support (or some kind of emulation).
>
>Ok, I have to redesign this part of my code:
>
>  def timeout_handler(sig,frame):
>    raise ValueError("timeout!")
>
>  signal.signal(signal.SIGALRM,timeout_handler)
>
>  while True:
>    chunk = fileo.read(bs)
>    sock.sendall(chunk)
>    (...)
>
>What is the best practise for a cross platform timeout handler?

I suggest you look at the socket.settimeout function. Avoid SIGALRM altogether.  
Then (untested):

  import socket
  ...
  socket.settimeout(timeout_in_seconds)
  ...
  while True:
    ...
    chunk = fileo.read(bs)
    try:
      sock.sendall(chunk)
    except socket.timeout as e:
      ... complain about timeout, reciting "e" in the message ...

Cheers,
Cameron Simpson <cs at zip.com.au>

I think you're confusing "recognizing" and "understanding" with "caring".
The net is cruel, sometimes, but always fair.
        - Rick Gordon <rickg at crl.com>


From marko at pacujo.net  Thu Nov 12 01:14:48 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 12 Nov 2015 08:14:48 +0200
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
Message-ID: <877flnu4kn.fsf@elektro.pacujo.net>

Terry Reedy <tjreedy at udel.edu>:

> The cross-platform 3.4 asyncio module has some functions with
> timeouts.

Even that doesn't forcefully interrupt an obnoxious blocking function
call like

   time.sleep(10000)

The original question claimed signal.alarm() would do the trick in
Linux. However, even that cannot be relied on as "man alarm" states:

   sleep(3) may be implemented using SIGALRM; mixing calls to alarm()
   and sleep(3) is a bad idea.

I'm thinking the only portable way is to run a watchdog process with
subprocess or multiprocessing.


Marko


From marko at pacujo.net  Thu Nov 12 01:21:14 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 12 Nov 2015 08:21:14 +0200
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <obL0y.222880$6i2.63495@fx35.am4>
 <5644005e$0$2932$c3e8da3$76491128@news.astraweb.com>
Message-ID: <8737wbu49x.fsf@elektro.pacujo.net>

Steven D'Aprano <steve+comp.lang.python at pearwood.info>:

> On Thursday 12 November 2015 04:48, Quivis wrote:
>
>> On Wed, 11 Nov 2015 08:34:30 -0800, Anas Belemlih wrote:
>> 
>>> md5
>> 
>> If those are md5 values stored inside files, wouldn't it be easier to
>> just hash them?
>> 
>> import hashlib
>> 
>> m1 = hashlib.sha224(open('f1').read()).hexdigest()
>> m2 = hashlib.sha224(open('f2').read()).hexdigest()
>
> I presume that the purpose of the exercise is to learn basic Python
> skills like looping.

And if you really wanted to compare two files that are known to contain
MD5 checksums, the simplest way is:

   with open('f1.md5') as f1, open('f2.md5') as f2:
       if f1.read() == f2.read():
           ...
       else:
           ...


Marko


From auriocus at gmx.de  Thu Nov 12 01:43:57 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 12 Nov 2015 07:43:57 +0100
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <877flnu4kn.fsf@elektro.pacujo.net>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net>
Message-ID: <n21cb4$agq$1@dont-email.me>

Am 12.11.15 um 07:14 schrieb Marko Rauhamaa:
> Terry Reedy <tjreedy at udel.edu>:
>
>> The cross-platform 3.4 asyncio module has some functions with
>> timeouts.
>
> Even that doesn't forcefully interrupt an obnoxious blocking function
> call like
>
>     time.sleep(10000)

A blocking call - granted. But what happens in a blocking loop, i.e.

for i in range(10000000000000000000000000):
	pass

?

My understanding of async is that it creates an event loop. In which 
case the loop has no chance to run within a block of code that computes 
anything, is that correct? Or does it hook into the interpreter and is 
able to interrupt the program between bytecodes?

> I'm thinking the only portable way is to run a watchdog process with
> subprocess or multiprocessing.

What about a thread which calls exit() after the timeout? Does that 
forcefully kill the whole process?

	Christian


From framstag at rus.uni-stuttgart.de  Thu Nov 12 01:58:33 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 12 Nov 2015 06:58:33 +0000 (UTC)
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
Message-ID: <n21dap$ae$1@news2.informatik.uni-stuttgart.de>

Terry Reedy <tjreedy at udel.edu> wrote:
> On 11/11/2015 11:16 AM, Ulli Horlacher wrote:
> > I am rewriting a Perl program into Python (2.7).
> 
> I recommend using 3.4+ if you possibly can.

It is not possible.
The main target platform offers only python 2.7

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From framstag at rus.uni-stuttgart.de  Thu Nov 12 02:22:18 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 12 Nov 2015 07:22:18 +0000 (UTC)
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net>
Message-ID: <n21ena$f8$1@news2.informatik.uni-stuttgart.de>

Marko Rauhamaa <marko at pacujo.net> wrote:

> I'm thinking the only portable way is to run a watchdog process with
> subprocess or multiprocessing.

How can a subprocess interrupt a function in another process?

For example: waiting for user input with a timeout.

raw_input("Hit ENTER to continue or wait 10 s")



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rosuav at gmail.com  Thu Nov 12 02:37:02 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 12 Nov 2015 18:37:02 +1100
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <n21cb4$agq$1@dont-email.me>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net> <n21cb4$agq$1@dont-email.me>
Message-ID: <CAPTjJmrjujycyc5hbL7SY4D0H0r+bKnCxj_fY9--rg5k9wgn5A@mail.gmail.com>

On Thu, Nov 12, 2015 at 5:43 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> My understanding of async is that it creates an event loop. In which case
> the loop has no chance to run within a block of code that computes anything,
> is that correct?

This is correct. At its simplest, asynchronous code is an abstraction
over the select() call, which basically says "Hey system, tell me when
(a) I can read from here, (b) I can write to here, or (c) I've been
waiting this long". The most common use is sockets; a web server has
its main listening socket (it becomes readable when someone connects),
any clients that haven't finished sending their requests yet (they
become readable when more data arrives), any clients that you're still
sending to (they become writeable when there's room in their output
buffers), and maybe some sort of periodic checks ("every hour, do
maintenance"). Whenever you finish a bit of processing (reading from a
client, sending to a client, whatever), you return to the "event
loop", which in this case would be select().

An async library makes all this look a lot cleaner in your code, but
ultimately, it's not preemptive. You still have to make sure the
processing doesn't take too long.

ChrisA


From 18518281186 at 126.com  Thu Nov 12 03:05:09 2015
From: 18518281186 at 126.com (Xiang Zhang)
Date: Thu, 12 Nov 2015 16:05:09 +0800
Subject: What is the meaning of Py_INCREF a static PyTypeObject?
Message-ID: <56444835.5020803@126.com>

Recently I am learning Python C API.

When I read the tutorial 
<https://docs.python.org/3/extending/newtypes.html#the-basics>, defining 
new types, I feel confused. After PyType_Ready(&noddy_NoddyType) comes 
Py_INCREF(&noddy_NoddyType). Actually noddy_NoddyType is a static struct 
so I don't understand why I need to Py_INCREF it. Since it's 
Py_INCREFed, does it mean sometimes we also need to Py_DECREF it? But 
then it seems that type_dealloc will be invoked and it will fail 
assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);

I haven't read the typeobject.c source code totally so I think I must 
have missed something. But I am quite confused. Hope someone can give me 
some hints. Thanks in advance.


From marko at pacujo.net  Thu Nov 12 03:15:48 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 12 Nov 2015 10:15:48 +0200
Subject: cross platform alternative for signal.SIGALRM?
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net>
 <n21ena$f8$1@news2.informatik.uni-stuttgart.de>
Message-ID: <87vb97skej.fsf@elektro.pacujo.net>

Ulli Horlacher <framstag at rus.uni-stuttgart.de>:

> Marko Rauhamaa <marko at pacujo.net> wrote:
>
>> I'm thinking the only portable way is to run a watchdog process with
>> subprocess or multiprocessing.
>
> How can a subprocess interrupt a function in another process?
>
> For example: waiting for user input with a timeout.
>
> raw_input("Hit ENTER to continue or wait 10 s")

By sending the parent a signal with os.kill().

Now, signal handling in Python is brittle so you must be careful:

  There is no way to ?block? signals temporarily from critical sections
  <URL: https://docs.python.org/2/library/signal.html>


Marko


From auriocus at gmx.de  Thu Nov 12 03:46:10 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 12 Nov 2015 09:46:10 +0100
Subject: Swig + Numpy.i with a const int16_t pointer
In-Reply-To: <05ae95fa-68f0-43ca-8b36-04a827c5d878@googlegroups.com>
References: <05ae95fa-68f0-43ca-8b36-04a827c5d878@googlegroups.com>
Message-ID: <n21jga$vea$1@dont-email.me>

Am 11.11.15 um 02:09 schrieb shriphanip at gmail.com:
> I am trying to wrap the following function with SWIG so I can call it from Python. The signature is:
>
> ```
> int WebRtcVad_Process(VadInst* handle, int fs, const int16_t* audio_frame, size_t frame_length);
> ```

This is thing is an array of 16 bit unsigned integers for input. The 
closest object in Python is a numpy array. There is a numpy.i available 
for Python, I'm not sure if it handles this case correctly. If you are 
unlucky, you need to write your own typemap.

	Christian




From auriocus at gmx.de  Thu Nov 12 04:16:35 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 12 Nov 2015 10:16:35 +0100
Subject: Swig + Numpy.i with a const int16_t pointer
In-Reply-To: <n21jga$vea$1@dont-email.me>
References: <05ae95fa-68f0-43ca-8b36-04a827c5d878@googlegroups.com>
 <n21jga$vea$1@dont-email.me>
Message-ID: <n21l9b$4vf$1@dont-email.me>

Am 12.11.15 um 09:46 schrieb Christian Gollwitzer:
> Am 11.11.15 um 02:09 schrieb shriphanip at gmail.com:
>> I am trying to wrap the following function with SWIG so I can call it
>> from Python. The signature is:
>>
>> ```
>> int WebRtcVad_Process(VadInst* handle, int fs, const int16_t*
>> audio_frame, size_t frame_length);
>> ```
>
> This is thing is an array of 16 bit unsigned integers for input. The
> closest object in Python is a numpy array. There is a numpy.i available
> for Python, I'm not sure if it handles this case correctly. If you are
> unlucky, you need to write your own typemap.

http://docs.scipy.org/doc/numpy/reference/swig.interface-file.html

It seems that you can create your own typemap easily using the macros 
provided by numpy.i; something like

%numpy_typemaps(int16_t, NPY_UINT16, int)

should be sufficient.

	Christian


From auriocus at gmx.de  Thu Nov 12 04:17:38 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 12 Nov 2015 10:17:38 +0100
Subject: Swig + Numpy.i with a const int16_t pointer
In-Reply-To: <n21l9b$4vf$1@dont-email.me>
References: <05ae95fa-68f0-43ca-8b36-04a827c5d878@googlegroups.com>
 <n21jga$vea$1@dont-email.me> <n21l9b$4vf$1@dont-email.me>
Message-ID: <n21lba$4vf$2@dont-email.me>

Am 12.11.15 um 10:16 schrieb Christian Gollwitzer:
> Am 12.11.15 um 09:46 schrieb Christian Gollwitzer:
>> Am 11.11.15 um 02:09 schrieb shriphanip at gmail.com:
>>> I am trying to wrap the following function with SWIG so I can call it
>>> from Python. The signature is:
>>>
>>> ```
>>> int WebRtcVad_Process(VadInst* handle, int fs, const int16_t*
>>> audio_frame, size_t frame_length);
>>> ```
>>
>> This is thing is an array of 16 bit unsigned integers for input. The
>> closest object in Python is a numpy array. There is a numpy.i available
>> for Python, I'm not sure if it handles this case correctly. If you are
>> unlucky, you need to write your own typemap.
>
> http://docs.scipy.org/doc/numpy/reference/swig.interface-file.html
>
> It seems that you can create your own typemap easily using the macros
> provided by numpy.i; something like
>
> %numpy_typemaps(int16_t, NPY_UINT16, int)
>
> should be sufficient.

That should be

  %numpy_typemaps(int16_t, NPY_INT16, int)

of course.
	


From breamoreboy at yahoo.co.uk  Thu Nov 12 04:32:22 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 12 Nov 2015 09:32:22 +0000
Subject: Hi
In-Reply-To: <SNT406-EAS1698A9EEF273B68B87176EFE9130@phx.gbl>
References: <SNT406-EAS1698A9EEF273B68B87176EFE9130@phx.gbl>
Message-ID: <n21mbj$bv8$1@ger.gmane.org>

On 11/11/2015 17:35, Cameron Houliston wrote:
> Can I have a link to use python
>
> Sent from Mail for Windows 10
>

I usually start with www.google.co.uk.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From lac at openend.se  Thu Nov 12 04:50:25 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 12 Nov 2015 10:50:25 +0100
Subject: Python.exe is not a valid Win32 application error message
In-Reply-To: <56435E8B.10103@gmail.com>
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
 <CAPTjJmpOYrpHzsFmBigF=wHEmVGp=SOpk9LsSF11=C-c4KH+6g@mail.gmail.com>
 <56435E8B.10103@gmail.com>
Message-ID: <201511120950.tAC9oP4c026463@fido.openend.se>

In a message of Wed, 11 Nov 2015 08:28:11 -0700, Michael Torrie writes:
>The Python website is looking very professional and polished these days.
> But we still don't have a simple message on the download page telling
>people Windows XP is no longer supported.  Given the number of people
>posting lately (several each week), I would think even with the limited
>time and resources of the python.org webmaster a little warning message
>would be in order.  Even when the installer is fixed, it would still be
>nice to have basic OS requirements listed before the download is ever
>clicked.

It's not webmaster, who is receiving as many of these requests
as python-list, but the pydotorg team.  There is a request in to
get this changed, it just hasn?t happened yet.

Laura



From tjreedy at udel.edu  Thu Nov 12 05:10:18 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 12 Nov 2015 05:10:18 -0500
Subject: Python Trouble
In-Reply-To: <DUB405-EAS254A6E4B3C370A303ECF884F8130@phx.gbl>
References: <DUB405-EAS254A6E4B3C370A303ECF884F8130@phx.gbl>
Message-ID: <n21oic$fvl$1@ger.gmane.org>

On 11/11/2015 3:01 PM, Kaif Mahmood wrote:
> I downloaded the recent version of Python and after it downloaded I tried IDLE. But when I tried to load it, it didn?t load and just acted as if nothing happened. All of the other features work fine, it?s just IDLE not working. I tried different versions but I encounter the same problem. The only way I managed to load it was by right clicking on previous files and clicking edit with IDLE; IDLE loaded but when I clicked run, it just froze and closed. Please help.

At a command line enter 'python -m idlelib' or 'python3 ...' on *nix. 
You should see some error message.

-- 
Terry Jan Reedy




From lac at openend.se  Thu Nov 12 05:14:56 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 12 Nov 2015 11:14:56 +0100
Subject: =?utf-8?Q?Python_Trouble?=
In-Reply-To: <DUB405-EAS254A6E4B3C370A303ECF884F8130@phx.gbl>
References: <DUB405-EAS254A6E4B3C370A303ECF884F8130@phx.gbl>
Message-ID: <201511121014.tACAEuxb029629@fido.openend.se>

In a message of Wed, 11 Nov 2015 20:01:46 +0000, Kaif Mahmood writes:

>I downloaded the recent version of Python and after it downloaded I
 tried IDLE. But when I tried to load it, it didn?t load and just
 acted as if nothing happened. All of the other features work fine,
 it?s just IDLE not working. I tried different versions but I
 encounter the same problem. The only way I managed to load it was by
 right clicking on previous files and clicking edit with IDLE; IDLE
 loaded but when I clicked run, it just froze and closed. Please help.

At the command line, run

python -m idlelib.idle

or

python3 -m idlelib.idle

and then reply here with that information.  Also what version of
Python you are trying to run on what OS.  (i.e 3.5 on Windows Vista)

Laura



From tjreedy at udel.edu  Thu Nov 12 05:15:52 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 12 Nov 2015 05:15:52 -0500
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <CAPTjJmrjujycyc5hbL7SY4D0H0r+bKnCxj_fY9--rg5k9wgn5A@mail.gmail.com>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net> <n21cb4$agq$1@dont-email.me>
 <CAPTjJmrjujycyc5hbL7SY4D0H0r+bKnCxj_fY9--rg5k9wgn5A@mail.gmail.com>
Message-ID: <n21osr$mp8$1@ger.gmane.org>

On 11/12/2015 2:37 AM, Chris Angelico wrote:
> On Thu, Nov 12, 2015 at 5:43 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
>> My understanding of async is that it creates an event loop. In which case
>> the loop has no chance to run within a block of code that computes anything,
>> is that correct?
>
> This is correct. At its simplest, asynchronous code is an abstraction
> over the select() call,

True on Unix-derived systems, where 'select' includes the various 
derivatives.  It is also an abstraction over the Windows completion 
calls, which are quite different.  The latter is why one must generally 
use a different event loop on Windows.  The point is that asyncio 
provides an *abstraction* such that after choosing the event loop, the 
rest of one's code is os-agnostic.

-- 
Terry Jan Reedy



From jongiddy at gmail.com  Thu Nov 12 06:03:51 2015
From: jongiddy at gmail.com (jongiddy)
Date: Thu, 12 Nov 2015 03:03:51 -0800 (PST)
Subject: Classic OOP in Python
In-Reply-To: <01adfef5-7edf-447c-9397-853c4fd65e53@googlegroups.com>
References: <23b2fae3-91d5-486b-9898-78b34bee486f@googlegroups.com>
 <16dc8c92-50e3-4fc8-ae25-cbc5b13e8971@googlegroups.com>
 <01adfef5-7edf-447c-9397-853c4fd65e53@googlegroups.com>
Message-ID: <6b0d08b3-5599-4952-85d2-a43c72ee71b2@googlegroups.com>

On Thursday, 18 June 2015 12:21:29 UTC+1, Jason P.  wrote:
> 
> I'm aware of duck typing. The point in using interfaces is to be explicit about the boundaries of a system.
> 
> Quite a red "Growing Object-Oriented Software, Guided by Tests", by the way. In fact interfaces are key components in the style of building software they propose, in good company with TDD.
> 
> Thx!


Late to the party, but I have added a package `jute` to PyPI which provides interface checking closer to the model used in Java (and other compiled OO languages). See https://github.com/jongiddy/jute


From rosuav at gmail.com  Thu Nov 12 06:38:49 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 12 Nov 2015 22:38:49 +1100
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <n21osr$mp8$1@ger.gmane.org>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net> <n21cb4$agq$1@dont-email.me>
 <CAPTjJmrjujycyc5hbL7SY4D0H0r+bKnCxj_fY9--rg5k9wgn5A@mail.gmail.com>
 <n21osr$mp8$1@ger.gmane.org>
Message-ID: <CAPTjJmopR2yEEdn_DKB7KdszSJWvySGm=eGStUQ--xMV6R_1gg@mail.gmail.com>

On Thu, Nov 12, 2015 at 9:15 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> On 11/12/2015 2:37 AM, Chris Angelico wrote:
>>
>> On Thu, Nov 12, 2015 at 5:43 PM, Christian Gollwitzer <auriocus at gmx.de>
>> wrote:
>>>
>>> My understanding of async is that it creates an event loop. In which case
>>> the loop has no chance to run within a block of code that computes
>>> anything,
>>> is that correct?
>>
>>
>> This is correct. At its simplest, asynchronous code is an abstraction
>> over the select() call,
>
>
> True on Unix-derived systems, where 'select' includes the various
> derivatives.  It is also an abstraction over the Windows completion calls,
> which are quite different.  The latter is why one must generally use a
> different event loop on Windows.  The point is that asyncio provides an
> *abstraction* such that after choosing the event loop, the rest of one's
> code is os-agnostic.

I've never done that kind of thing on Windows, so I'm not sure how it
works; it's still broadly based on I/O availability, right? And
ultimately, it comes down to "go back to the event loop so others can
run".

ChrisA


From python.list at tim.thechases.com  Thu Nov 12 06:48:12 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 12 Nov 2015 05:48:12 -0600
Subject: new to python, help please !!
In-Reply-To: <8737wbu49x.fsf@elektro.pacujo.net>
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <obL0y.222880$6i2.63495@fx35.am4>
 <5644005e$0$2932$c3e8da3$76491128@news.astraweb.com>
 <8737wbu49x.fsf@elektro.pacujo.net>
Message-ID: <20151112054812.3603d4de@bigbox.christie.dr>

On 2015-11-12 08:21, Marko Rauhamaa wrote:
> And if you really wanted to compare two files that are known to
> contain MD5 checksums, the simplest way is:
> 
>    with open('f1.md5') as f1, open('f2.md5') as f2:
>        if f1.read() == f2.read():
>            ...
>        else:
>            ...

Though that suffers if the files are large.  Might try

  CHUNK_SIZE = 4 * 1024 # read 4k chunks
  # chunk_offset = 0
  with open('f1.md5') as f1, open('f2.md5') as f2:
    while True:
      c1 = f1.read(CHUNK_SIZE)
      c2 = f2.read(CHUNK_SIZE)
      if c1 or c2:
        # chunk_offset += 1
        if c1 != c2:
          not_the_same(c1, c2)
          # not_the_same(chunk_offset * CHUNK_SIZE, c1, c2)
          break
      else: # EOF
        the_same()
        break

which should perform better if the files are huge

-tkc





From rxjwg98 at gmail.com  Thu Nov 12 08:57:53 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 12 Nov 2015 05:57:53 -0800 (PST)
Subject: What is wrong in this example code?
Message-ID: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>

Hi,

I run a code snippet from link:
http://www.python-course.eu/inheritance_example.php

It is found that there is an error in this loop:

for i in xrange(10000):
    x.tick()
print(x)
SyntaxError: invalid syntax


I have modified it to:
for i in x range(10000):
    x.tick()
print(x)
SyntaxError: invalid syntax

it still has an error. What could be wrong?

Thanks,


....
class Clock(object):

    def __init__(self,hours=0, minutes=0, seconds=0):
        self.__hours = hours
        self.__minutes = minutes
        self.__seconds = seconds

    def set(self,hours, minutes, seconds=0):
        self.__hours = hours
        self.__minutes = minutes
        self.__seconds = seconds

    def tick(self):
        """ Time will be advanced by one second """
        if self.__seconds == 59:
            self.__seconds = 0
            if (self.__minutes == 59):
                self.__minutes = 0
                self.__hours = 0 if self.__hours==23  else self.__hours+1
	    else:
		self.__minutes += 1;
	else:
            self.__seconds += 1;

    def display(self):
        print("%d:%d:%d" % (self.__hours, self.__minutes, self.__seconds))

    def __str__(self):
        return "%2d:%2d:%2d" % (self.__hours, self.__minutes, self.__seconds)

x = Clock()
print(x)
for i in xrange(10000):
    x.tick()
print(x)


From tjreedy at udel.edu  Thu Nov 12 09:01:40 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 12 Nov 2015 09:01:40 -0500
Subject: cross platform alternative for signal.SIGALRM?
In-Reply-To: <CAPTjJmopR2yEEdn_DKB7KdszSJWvySGm=eGStUQ--xMV6R_1gg@mail.gmail.com>
References: <n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>
 <mailman.251.1447292269.16136.python-list@python.org>
 <877flnu4kn.fsf@elektro.pacujo.net> <n21cb4$agq$1@dont-email.me>
 <CAPTjJmrjujycyc5hbL7SY4D0H0r+bKnCxj_fY9--rg5k9wgn5A@mail.gmail.com>
 <n21osr$mp8$1@ger.gmane.org>
 <CAPTjJmopR2yEEdn_DKB7KdszSJWvySGm=eGStUQ--xMV6R_1gg@mail.gmail.com>
Message-ID: <n22647$nks$1@ger.gmane.org>

On 11/12/2015 6:38 AM, Chris Angelico wrote:
> On Thu, Nov 12, 2015 at 9:15 PM, Terry Reedy <tjreedy at udel.edu> wrote:
>> On 11/12/2015 2:37 AM, Chris Angelico wrote:
>>>
>>> On Thu, Nov 12, 2015 at 5:43 PM, Christian Gollwitzer <auriocus at gmx.de>
>>> wrote:
>>>>
>>>> My understanding of async is that it creates an event loop. In which case
>>>> the loop has no chance to run within a block of code that computes
>>>> anything,
>>>> is that correct?
>>>
>>>
>>> This is correct. At its simplest, asynchronous code is an abstraction
>>> over the select() call,
>>
>>
>> True on Unix-derived systems, where 'select' includes the various
>> derivatives.  It is also an abstraction over the Windows completion calls,
>> which are quite different.  The latter is why one must generally use a
>> different event loop on Windows.  The point is that asyncio provides an
>> *abstraction* such that after choosing the event loop, the rest of one's
>> code is os-agnostic.
>
> I've never done that kind of thing on Windows, so I'm not sure how it
> works; it's still broadly based on I/O availability, right?

That is the general abstraction.  But there was something in the design 
discussion about a difference between 'edge' versus 'level' triggering 
that made it a challenge to get something more detailed that covers both 
implementations.

> ultimately, it comes down to "go back to the event loop so others can
> run".


-- 
Terry Jan Reedy



From rxjwg98 at gmail.com  Thu Nov 12 09:07:45 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 12 Nov 2015 06:07:45 -0800 (PST)
Subject: What is wrong in this example code?
In-Reply-To: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>
References: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>
Message-ID: <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>

On Thursday, November 12, 2015 at 8:58:33 AM UTC-5, fl wrote:
> Hi,
> 
> I run a code snippet from link:
> http://www.python-course.eu/inheritance_example.php
> 
> It is found that there is an error in this loop:
> 
> for i in xrange(10000):
>     x.tick()
> print(x)
> SyntaxError: invalid syntax
> 
> 
> I have modified it to:
> for i in x range(10000):
>     x.tick()
> print(x)
> SyntaxError: invalid syntax
> 
> it still has an error. What could be wrong?
> 
> Thanks,
> 
> 
> ....
> class Clock(object):
> 
>     def __init__(self,hours=0, minutes=0, seconds=0):
>         self.__hours = hours
>         self.__minutes = minutes
>         self.__seconds = seconds
> 
>     def set(self,hours, minutes, seconds=0):
>         self.__hours = hours
>         self.__minutes = minutes
>         self.__seconds = seconds
> 
>     def tick(self):
>         """ Time will be advanced by one second """
>         if self.__seconds == 59:
>             self.__seconds = 0
>             if (self.__minutes == 59):
>                 self.__minutes = 0
>                 self.__hours = 0 if self.__hours==23  else self.__hours+1
> 	    else:
> 		self.__minutes += 1;
> 	else:
>             self.__seconds += 1;
> 
>     def display(self):
>         print("%d:%d:%d" % (self.__hours, self.__minutes, self.__seconds))
> 
>     def __str__(self):
>         return "%2d:%2d:%2d" % (self.__hours, self.__minutes, self.__seconds)
> 
> x = Clock()
> print(x)
> for i in xrange(10000):
>     x.tick()
> print(x)

Solved it by this:
print(x)
for i in range(1, 10000):
         x.tick()
print(x)

Thanks,


From paul.hermeneutic at gmail.com  Thu Nov 12 09:27:29 2015
From: paul.hermeneutic at gmail.com (paul.hermeneutic at gmail.com)
Date: Thu, 12 Nov 2015 07:27:29 -0700
Subject: new to python, help please !!
In-Reply-To: <20151112054812.3603d4de@bigbox.christie.dr>
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <obL0y.222880$6i2.63495@fx35.am4>
 <5644005e$0$2932$c3e8da3$76491128@news.astraweb.com>
 <8737wbu49x.fsf@elektro.pacujo.net>
 <20151112054812.3603d4de@bigbox.christie.dr>
Message-ID: <CAJ4+4ap09dtvr1vB41mBPJ8Y6jg=yE30W47ejUa57UYy+tC1tw@mail.gmail.com>

Would some form of subprocess.Popen() on cmp or fc /b be easier?
On Nov 12, 2015 7:13 AM, "Tim Chase" <python.list at tim.thechases.com> wrote:

> On 2015-11-12 08:21, Marko Rauhamaa wrote:
> > And if you really wanted to compare two files that are known to
> > contain MD5 checksums, the simplest way is:
> >
> >    with open('f1.md5') as f1, open('f2.md5') as f2:
> >        if f1.read() == f2.read():
> >            ...
> >        else:
> >            ...
>
> Though that suffers if the files are large.  Might try
>
>   CHUNK_SIZE = 4 * 1024 # read 4k chunks
>   # chunk_offset = 0
>   with open('f1.md5') as f1, open('f2.md5') as f2:
>     while True:
>       c1 = f1.read(CHUNK_SIZE)
>       c2 = f2.read(CHUNK_SIZE)
>       if c1 or c2:
>         # chunk_offset += 1
>         if c1 != c2:
>           not_the_same(c1, c2)
>           # not_the_same(chunk_offset * CHUNK_SIZE, c1, c2)
>           break
>       else: # EOF
>         the_same()
>         break
>
> which should perform better if the files are huge
>
> -tkc
>
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From __peter__ at web.de  Thu Nov 12 09:56:40 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 12 Nov 2015 15:56:40 +0100
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <20151111110655.7293d3b7@bigbox.christie.dr>
Message-ID: <n229b9$hh9$1@ger.gmane.org>

Tim Chase wrote:

>   with open("file1.md5") as a, open("file2.md5") as b:
>     for s1, s2 in zip(a, b):
>       if s1 != s2:
>         print("Files differ")

Note that this will not detect extra lines in one of the files.
I recommend that you use itertools.zip_longest (izip_longest in Python 2) 
instead of the built-in zip().



From python.list at tim.thechases.com  Thu Nov 12 10:00:58 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 12 Nov 2015 09:00:58 -0600
Subject: new to python, help please !!
In-Reply-To: <n229b9$hh9$1@ger.gmane.org>
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <20151111110655.7293d3b7@bigbox.christie.dr>
 <n229b9$hh9$1@ger.gmane.org>
Message-ID: <20151112090058.0834a645@bigbox.christie.dr>

On 2015-11-12 15:56, Peter Otten wrote:
> Tim Chase wrote:
> 
> >   with open("file1.md5") as a, open("file2.md5") as b:
> >     for s1, s2 in zip(a, b):
> >       if s1 != s2:
> >         print("Files differ")
> 
> Note that this will not detect extra lines in one of the files.
> I recommend that you use itertools.zip_longest (izip_longest in
> Python 2) instead of the built-in zip().

Yeah, I noticed that after pushing <send> but then posted a later
version that just read chunks of the file which should catch that
file-size difference.  Or, as in that other message, prefix it with
an fstat() check to compare file-sizes so that you don't even have to
open the files if the sizes differ.

-tkc




From gokoproject at gmail.com  Thu Nov 12 10:10:06 2015
From: gokoproject at gmail.com (John Wong)
Date: Thu, 12 Nov 2015 10:10:06 -0500
Subject: What is wrong in this example code?
In-Reply-To: <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>
References: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>
 <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>
Message-ID: <CACCLA56ZnhkNq==_S9-NpNwQN4TNxsm921fqN5TwiXsPMMLyYQ@mail.gmail.com>

If you are using Python 3 you will need to change xrange to range, but the
error shouldn't be invalid syntax. I remember it should just name name not
found/not defined. So if you are not using Python 3, range and xrange do
still in Python 2 and they have different use case.

So i am really curious how you fixed it. It sounds more like some issue
with space rather, but still glad you solved it somehow.

On Thu, Nov 12, 2015 at 9:07 AM, fl <rxjwg98 at gmail.com> wrote:

> On Thursday, November 12, 2015 at 8:58:33 AM UTC-5, fl wrote:
> > Hi,
> >
> > I run a code snippet from link:
> > http://www.python-course.eu/inheritance_example.php
> >
> > It is found that there is an error in this loop:
> >
> > for i in xrange(10000):
> >     x.tick()
> > print(x)
> > SyntaxError: invalid syntax
> >
> >
> > I have modified it to:
> > for i in x range(10000):
> >     x.tick()
> > print(x)
> > SyntaxError: invalid syntax
> >
> > it still has an error. What could be wrong?
> >
> > Thanks,
> >
> >
> > ....
> > class Clock(object):
> >
> >     def __init__(self,hours=0, minutes=0, seconds=0):
> >         self.__hours = hours
> >         self.__minutes = minutes
> >         self.__seconds = seconds
> >
> >     def set(self,hours, minutes, seconds=0):
> >         self.__hours = hours
> >         self.__minutes = minutes
> >         self.__seconds = seconds
> >
> >     def tick(self):
> >         """ Time will be advanced by one second """
> >         if self.__seconds == 59:
> >             self.__seconds = 0
> >             if (self.__minutes == 59):
> >                 self.__minutes = 0
> >                 self.__hours = 0 if self.__hours==23  else self.__hours+1
> >           else:
> >               self.__minutes += 1;
> >       else:
> >             self.__seconds += 1;
> >
> >     def display(self):
> >         print("%d:%d:%d" % (self.__hours, self.__minutes,
> self.__seconds))
> >
> >     def __str__(self):
> >         return "%2d:%2d:%2d" % (self.__hours, self.__minutes,
> self.__seconds)
> >
> > x = Clock()
> > print(x)
> > for i in xrange(10000):
> >     x.tick()
> > print(x)
>
> Solved it by this:
> print(x)
> for i in range(1, 10000):
>          x.tick()
> print(x)
>
> Thanks,
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From __peter__ at web.de  Thu Nov 12 10:41:33 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 12 Nov 2015 16:41:33 +0100
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <20151111110655.7293d3b7@bigbox.christie.dr> <n229b9$hh9$1@ger.gmane.org>
 <20151112090058.0834a645@bigbox.christie.dr>
Message-ID: <n22bve$sou$1@ger.gmane.org>

Tim Chase wrote:

> On 2015-11-12 15:56, Peter Otten wrote:
>> Tim Chase wrote:
>> 
>> >   with open("file1.md5") as a, open("file2.md5") as b:
>> >     for s1, s2 in zip(a, b):
>> >       if s1 != s2:
>> >         print("Files differ")
>> 
>> Note that this will not detect extra lines in one of the files.
>> I recommend that you use itertools.zip_longest (izip_longest in
>> Python 2) instead of the built-in zip().
> 
> Yeah, I noticed that after pushing <send> but then posted a later
> version that just read chunks of the file which should catch that
> file-size difference.  Or, as in that other message, prefix it with
> an fstat() check to compare file-sizes so that you don't even have to
> open the files if the sizes differ.
> 
> -tkc

>>> os.path.getsize("file1.md5")
10
>>> os.path.getsize("file2.md5")
10
>>> with open("file1.md5") as a, open("file2.md5") as b:
...     for s, t in zip(a, b):
...         if s != t: print("different")
... 
>>> from itertools import zip_longest
>>> with open("file1.md5") as a, open("file2.md5") as b:
...     for s, t in zip_longest(a, b):
...         if s != t: print("different")
... 
different

I admit I cheated and used Python 3 ;)




From johnzzhao at gmail.com  Thu Nov 12 10:47:55 2015
From: johnzzhao at gmail.com (John Zhao)
Date: Thu, 12 Nov 2015 07:47:55 -0800 (PST)
Subject: can ConfigParser deal with repeating section header?
Message-ID: <95dc81c4-31eb-4f45-8b9c-20a03b2f0caa@googlegroups.com>

I have a configuration file with repeating sections, for example, 

[INSTANCE]
Name=a

[INSTANCE]
Name=b


I hope I can use ConfigParser to read the file and store the configuration settings in arrays.  

Is that possible?

Thanks a lot.

John


From mjoerg.phone at gmail.com  Thu Nov 12 10:57:51 2015
From: mjoerg.phone at gmail.com (PythonDude)
Date: Thu, 12 Nov 2015 07:57:51 -0800 (PST)
Subject: don't understand matrix-multiplication should be reversed in python?
Message-ID: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>

Hi all,

I've come around a webpage with python-tutorial/description for obtaining something and I'll solve this:

R = p^T w

where R is a vector and p^T is the transpose of another vector.

...
p is a Nx1 column vector, so p^T turns into a 1xN row vector which can be multiplied with the
Nx1 weight (column) vector w to give a scalar result. This is equivalent to the dot
product used in the code. Keep in mind that Python has a reversed definition of
rows and columns and the accurate NumPy version of the previous equation would
be R = w * p.T
...

(source: http://blog.quantopian.com/markowitz-portfolio-optimization-2/ )

I don't understand this: "Keep in mind that Python has a reversed definition of
rows and columns and the accurate NumPy version of the previous equation would
be R = w * p.T"

Not true for numpy, is it? This page: http://mathesaurus.sourceforge.net/matlab-numpy.html says it python and matlab looks quite similar...

Anyone could please explain or elaborate on exactly this (quote): "Keep in mind that Python has a reversed definition of rows and columns"???

That I don't understand - thank you for any hints/guidance/explanations/ideas/suggestions etc!



From python.list at tim.thechases.com  Thu Nov 12 10:59:54 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Thu, 12 Nov 2015 09:59:54 -0600
Subject: can ConfigParser deal with repeating section header?
In-Reply-To: <95dc81c4-31eb-4f45-8b9c-20a03b2f0caa@googlegroups.com>
References: <95dc81c4-31eb-4f45-8b9c-20a03b2f0caa@googlegroups.com>
Message-ID: <20151112095954.4438eb5b@bigbox.christie.dr>

On 2015-11-12 07:47, John Zhao wrote:
> I have a configuration file with repeating sections, for example, 
> 
> [INSTANCE]
> Name=a
> 
> [INSTANCE]
> Name=b
> 
> I hope I can use ConfigParser to read the file and store the
> configuration settings in arrays.  
> 
> Is that possible?

Not with the standard library's ConfigParser:

  >>> from cStringIO import StringIO
  >>> from ConfigParser import ConfigParser
  >>> ini = StringIO("""[INSTANCE]
  ... Name=a
  ...
  ... [INSTANCE]
  ... Name=b
  ... """)
  >>> cp = ConfigParser()
  >>> cp.readfp(ini)
  >>> cp.sections() # note: only one section
  ['INSTANCE']
  >>> cp.get("INSTANCE", "Name") # note: only the last value
  'b'

It also fails to catch multiple values with the same key:

  [INSTANCE]
  Name=a
  Name=b

doesn't give you

  cp.get("INSTANCE", "Name") == ["a", "b"]


-tkc






From ian.g.kelly at gmail.com  Thu Nov 12 11:34:33 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 12 Nov 2015 09:34:33 -0700
Subject: don't understand matrix-multiplication should be reversed in
 python?
In-Reply-To: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
Message-ID: <CALwzidnaymY2X=R3s8fuoEcS4NDx=rSn5w5N7=-EhqV+sZPs0Q@mail.gmail.com>

On Thu, Nov 12, 2015 at 8:57 AM, PythonDude <mjoerg.phone at gmail.com> wrote:
> Hi all,
>
> I've come around a webpage with python-tutorial/description for obtaining something and I'll solve this:
>
> R = p^T w
>
> where R is a vector and p^T is the transpose of another vector.
>
> ...
> p is a Nx1 column vector, so p^T turns into a 1xN row vector which can be multiplied with the
> Nx1 weight (column) vector w to give a scalar result. This is equivalent to the dot
> product used in the code. Keep in mind that Python has a reversed definition of
> rows and columns and the accurate NumPy version of the previous equation would
> be R = w * p.T
> ...
>
> (source: http://blog.quantopian.com/markowitz-portfolio-optimization-2/ )
>
> I don't understand this: "Keep in mind that Python has a reversed definition of
> rows and columns and the accurate NumPy version of the previous equation would
> be R = w * p.T"
>
> Not true for numpy, is it? This page: http://mathesaurus.sourceforge.net/matlab-numpy.html says it python and matlab looks quite similar...
>
> Anyone could please explain or elaborate on exactly this (quote): "Keep in mind that Python has a reversed definition of rows and columns"???
>
> That I don't understand - thank you for any hints/guidance/explanations/ideas/suggestions etc!

py> import numpy
py> p = numpy.reshape(range(5), (5,1))
py> p
array([[0],
       [1],
       [2],
       [3],
       [4]])
py> p.T
array([[0, 1, 2, 3, 4]])
py> p.dot(p.T)
array([[ 0,  0,  0,  0,  0],
       [ 0,  1,  2,  3,  4],
       [ 0,  2,  4,  6,  8],
       [ 0,  3,  6,  9, 12],
       [ 0,  4,  8, 12, 16]])
py> p.T.dot(p)
array([[30]])
py> m = numpy.asmatrix(p)
py> m
matrix([[0],
        [1],
        [2],
        [3],
        [4]])
py> m.T
matrix([[0, 1, 2, 3, 4]])
py> m * m.T
matrix([[ 0,  0,  0,  0,  0],
        [ 0,  1,  2,  3,  4],
        [ 0,  2,  4,  6,  8],
        [ 0,  3,  6,  9, 12],
        [ 0,  4,  8, 12, 16]])
py> m.T * m
matrix([[30]])

Yeah, I don't know what that person is talking about either. It looks
correct to me.


From torriem at gmail.com  Thu Nov 12 11:47:56 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 12 Nov 2015 09:47:56 -0700
Subject: Python.exe is not a valid Win32 application error message
In-Reply-To: <53684bd0ecp0krft87qlerlkobh8kjp575@4ax.com>
References: <1913826683.1878058.1447115663273.JavaMail.yahoo.ref@mail.yahoo.com>
 <1913826683.1878058.1447115663273.JavaMail.yahoo@mail.yahoo.com>
 <mailman.241.1447247613.16136.python-list@python.org>
 <53684bd0ecp0krft87qlerlkobh8kjp575@4ax.com>
Message-ID: <5644C2BC.8010809@gmail.com>

On 11/11/2015 09:43 PM, Steve Hayes wrote:
> That is useful to know.
> 
> I get messages (from Glary Utilities) that some of my programs 
> (including Python) need to be updated, but when I've downloaded and 
> updated them, the update hasn't worked.

Such utilities seem to cause more trouble than they're worth.


From rxjwg98 at gmail.com  Thu Nov 12 12:20:02 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 12 Nov 2015 09:20:02 -0800 (PST)
Subject: Why does 'as' not recognized?
Message-ID: <8ddbc8fd-ebdb-4cd2-8e3b-b0e1f5142e76@googlegroups.com>

Hi,

When I try the following, python does not know 'as'. Why doesn't it?
Thanks,



>>> cats = ['Tom', 'Snappy', 'Kitty', 'Jessie', 'Chester']
>>> 
>>> type(cats)
<type 'list'>
>>> cats[2]
'Kitty'
>>> as=cats[2]
SyntaxError: invalid syntax
>>> as=cats
SyntaxError: invalid syntax
>>> as
SyntaxError: invalid syntax


From gordon at panix.com  Thu Nov 12 12:24:32 2015
From: gordon at panix.com (John Gordon)
Date: Thu, 12 Nov 2015 17:24:32 +0000 (UTC)
Subject: Why does 'as' not recognized?
References: <8ddbc8fd-ebdb-4cd2-8e3b-b0e1f5142e76@googlegroups.com>
Message-ID: <n22i0g$nlg$1@reader1.panix.com>

In <8ddbc8fd-ebdb-4cd2-8e3b-b0e1f5142e76 at googlegroups.com> fl <rxjwg98 at gmail.com> writes:

> >>> cats = ['Tom', 'Snappy', 'Kitty', 'Jessie', 'Chester']
> >>> 
> >>> type(cats)
> <type 'list'>
> >>> cats[2]
> 'Kitty'
> >>> as=cats[2]
> SyntaxError: invalid syntax
> >>> as=cats
> SyntaxError: invalid syntax
> >>> as
> SyntaxError: invalid syntax

'as' is a python language keyword, and cannot be used for variable names.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From jason.swails at gmail.com  Thu Nov 12 13:52:10 2015
From: jason.swails at gmail.com (Jason Swails)
Date: Thu, 12 Nov 2015 13:52:10 -0500
Subject: What is the meaning of Py_INCREF a static PyTypeObject?
In-Reply-To: <56444835.5020803@126.com>
References: <56444835.5020803@126.com>
Message-ID: <CAEk9e3pP6H=6P68p6r0iNiPYh0HF9kGemTFTnPbyLf2Acx1wgg@mail.gmail.com>

On Thu, Nov 12, 2015 at 3:05 AM, Xiang Zhang <18518281186 at 126.com> wrote:

> Recently I am learning Python C API.
>
> When I read the tutorial <
> https://docs.python.org/3/extending/newtypes.html#the-basics>, defining
> new types, I feel confused. After PyType_Ready(&noddy_NoddyType) comes
> Py_INCREF(&noddy_NoddyType). Actually noddy_NoddyType is a static struct so
> I don't understand why I need to Py_INCREF it. Since it's Py_INCREFed, does
> it mean sometimes we also need to Py_DECREF it? But then it seems that
> type_dealloc will be invoked and it will fail assert(type->tp_flags &
> Py_TPFLAGS_HEAPTYPE);
>

?It is a module attribute, so when the module is imported it has to have a
single reference (the reference *in* the module).  If you don't INCREF it,
then it will have a refcount of 0, and immediately be ready for garbage
collection.  So if you try to use the type from the module, you could get a
segfault because it's trying to use an object (type definition) that was
already destroyed.

Note that you don't *always* have to INCREF objects after you create them
in C.  Some macros and function do that for you.  And in some cases, all
you want or need is a borrowed reference.  In those cases, Py_INCREF is
unnecessary.

The DECREF will be done when it's normally done in Python.  If you do
something like

import noddy
del noddy.NoddyType

?All that's really doing is removing NoddyType from the noddy namespace and
Py_DECREFing it.  Alternatively, doing

import noddy
noddy.NoddyType = 10 # rebind the name

Then the original object NoddyType was pointing to will be DECREFed and
NoddyType will point to an object taking the value of 10.

HTH,
Jason


From amorawski at magna-power.com  Thu Nov 12 14:38:14 2015
From: amorawski at magna-power.com (amorawski at magna-power.com)
Date: Thu, 12 Nov 2015 11:38:14 -0800 (PST)
Subject: can ConfigParser deal with repeating section header?
In-Reply-To: <95dc81c4-31eb-4f45-8b9c-20a03b2f0caa@googlegroups.com>
References: <95dc81c4-31eb-4f45-8b9c-20a03b2f0caa@googlegroups.com>
Message-ID: <d6f0cc21-dfcc-4572-85aa-777daf59112b@googlegroups.com>

On Thursday, November 12, 2015 at 10:48:11 AM UTC-5, John Zhao wrote:
> I have a configuration file with repeating sections, for example, 
> 
> [INSTANCE]
> Name=a
> 
> [INSTANCE]
> Name=b
> 
> 
> I hope I can use ConfigParser to read the file and store the configuration settings in arrays.  
> 
> Is that possible?
> 
> Thanks a lot.
> 
> John

Here is one of possible solutions:
http://stackoverflow.com/questions/9876059/parsing-configure-file-with-same-section-name-in-python


From denismfmcmahon at gmail.com  Thu Nov 12 14:49:54 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Thu, 12 Nov 2015 19:49:54 -0000 (UTC)
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
 <obL0y.222880$6i2.63495@fx35.am4>
 <5644005e$0$2932$c3e8da3$76491128@news.astraweb.com>
 <po41y.186836$wR.71600@fx43.am4>
Message-ID: <n22qh2$m26$1@dont-email.me>

On Thu, 12 Nov 2015 17:55:33 +0000, Quivis wrote:

> On Thu, 12 Nov 2015 13:58:35 +1100, Steven D'Aprano wrote:
> 
>> horribly inefficient
> 
> Assuming it was md5 values, who cares? Those are small.

A file of 160 million md5 hashes as 32 character hex strings is a huge 
file. Your method calculates the hash over both files to test whether the 
contents are different. If the input files are both lists of 160 million 
md5 hashes, you're calculating the hash of two 5 gigabyte files.

In your method the size of the lines of data is irrelevant to the 
execution time, the execution time varies with the size of the datafiles.
-- 
Denis McMahon, denismfmcmahon at gmail.com


From PointedEars at web.de  Thu Nov 12 15:40:12 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Thu, 12 Nov 2015 21:40:12 +0100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
Message-ID: <10882952.phYABH7ckh@PointedEars.de>

Chris Angelico wrote:

> [?] Ben Finney [?] wrote:
>> I recommend you ignore that request; ?Bartc? is fine as a name here,
>> IMO.
> 
> Given that LARTC means Linux Advanced Routing and Traffic Control, I'm
> guessing Bartc is all about *BSD networking? :)

I thought LART were the Luser Attitude Readjustment Tool ;-)

And on GABELNs [1] it is considered polite to post using your real name.  
Lack of politeness towards the people whom would otherwise be willing to 
help you may cause you to be ignored by them instead.  You have been warned.

BTW, it?s attribution *line*, _not_ attribution novel.

[1] {Group Area Board Echo List Newsgroup}s

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From torriem at gmail.com  Thu Nov 12 15:40:22 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 12 Nov 2015 13:40:22 -0700
Subject: Hi
In-Reply-To: <n21mbj$bv8$1@ger.gmane.org>
References: <SNT406-EAS1698A9EEF273B68B87176EFE9130@phx.gbl>
 <n21mbj$bv8$1@ger.gmane.org>
Message-ID: <5644F936.8040402@gmail.com>

On 11/12/2015 02:32 AM, Mark Lawrence wrote:
> On 11/11/2015 17:35, Cameron Houliston wrote:
>> Can I have a link to use python
>>
>> Sent from Mail for Windows 10
>>
> 
> I usually start with www.google.co.uk.

I think Windows 10 blocks Google. :)

And of course the official home of Python is https://www.python.org/



From denismfmcmahon at gmail.com  Thu Nov 12 16:24:17 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Thu, 12 Nov 2015 21:24:17 -0000 (UTC)
Subject: new to python, help please !!
References: <93aef8e5-3d6f-41f4-a625-cd3c2007686e@googlegroups.com>
Message-ID: <n23020$m26$2@dont-email.me>

On Wed, 11 Nov 2015 08:34:30 -0800, Anas Belemlih wrote:

> i am  a beginning programmer,  i am trying to write a simple code to
> compare two character sets in 2 seperate files. ( 2 hash value files
> basically)

Why? If you simply wish to compare two files, most operating systems 
provide executable tools at the OS level which are more efficient than 
anything you will write in a scripting language.

Lesson 1 of computing. Use the right tool for the job. Writing a new 
program is not always the right tool.
-- 
Denis McMahon, denismfmcmahon at gmail.com


From rxjwg98 at gmail.com  Thu Nov 12 16:34:58 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 12 Nov 2015 13:34:58 -0800 (PST)
Subject: Is it useful for re.M in this example?
Message-ID: <fc8a4061-5156-41c8-bfd7-d9a8da462418@googlegroups.com>

Hi,

I follow a web site on learning Python re. I have read the function
 description of re.m, as below.


re.M	Makes $ match the end of a line (not just the end of the string) and
 makes ^ match the start of any line (not just the start of the string).

But I don't see the reason to put re.M in the example project:



#!/usr/bin/python
import re

line = "Cats are smarter than dogs";

matchObj = re.match( r'dogs', line, re.M|re.I)
if matchObj:
   print "match --> matchObj.group() : ", matchObj.group()
else:
   print "No match!!"


The tutorial (http://www.tutorialspoint.com/python/python_reg_expressions.htm)
is for a beginner as I. Is there something I don't see in the example?

Thanks,


From robert.kern at gmail.com  Thu Nov 12 16:56:51 2015
From: robert.kern at gmail.com (Robert Kern)
Date: Thu, 12 Nov 2015 21:56:51 +0000
Subject: don't understand matrix-multiplication should be reversed in
 python?
In-Reply-To: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
Message-ID: <n231v2$5hg$1@ger.gmane.org>

On 2015-11-12 15:57, PythonDude wrote:
> Hi all,
>
> I've come around a webpage with python-tutorial/description for obtaining something and I'll solve this:
>
> R = p^T w
>
> where R is a vector and p^T is the transpose of another vector.
>
> ...
> p is a Nx1 column vector, so p^T turns into a 1xN row vector which can be multiplied with the
> Nx1 weight (column) vector w to give a scalar result. This is equivalent to the dot
> product used in the code. Keep in mind that Python has a reversed definition of
> rows and columns and the accurate NumPy version of the previous equation would
> be R = w * p.T
> ...
>
> (source: http://blog.quantopian.com/markowitz-portfolio-optimization-2/ )
>
> I don't understand this: "Keep in mind that Python has a reversed definition of
> rows and columns and the accurate NumPy version of the previous equation would
> be R = w * p.T"
>
> Not true for numpy, is it? This page: http://mathesaurus.sourceforge.net/matlab-numpy.html says it python and matlab looks quite similar...
>
> Anyone could please explain or elaborate on exactly this (quote): "Keep in mind that Python has a reversed definition of rows and columns"???

He's wrong, simply put. There is no "reversed definition of rows and columns". 
He simply instantiated the two vectors as row-vectors instead of column-vectors, 
which he could have easily done, so he had to flip the matrix expression.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco



From gordon at panix.com  Thu Nov 12 17:00:32 2015
From: gordon at panix.com (John Gordon)
Date: Thu, 12 Nov 2015 22:00:32 +0000 (UTC)
Subject: Is it useful for re.M in this example?
References: <fc8a4061-5156-41c8-bfd7-d9a8da462418@googlegroups.com>
Message-ID: <n23260$kkj$2@reader1.panix.com>

In <fc8a4061-5156-41c8-bfd7-d9a8da462418 at googlegroups.com> fl <rxjwg98 at gmail.com> writes:

> re.M	Makes $ match the end of a line (not just the end of the string) and
>  makes ^ match the start of any line (not just the start of the string).

> But I don't see the reason to put re.M in the example project:

That's because your sample string does not contain newline characters.
If it did, you would see the effect of re.M.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From steve at pearwood.info  Thu Nov 12 17:04:54 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 13 Nov 2015 09:04:54 +1100
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
 <10882952.phYABH7ckh@PointedEars.de>
Message-ID: <56450d07$0$1584$c3e8da3$5496439d@news.astraweb.com>

On Fri, 13 Nov 2015 07:40 am, Thomas 'PointedEars' Lahn wrote:

> And on GABELNs [1] it is considered polite to post using your real name.

Falsehoods programmers believe about names:

http://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/


> You have been warned.

And you should consider the irony, and hypocrisy, of somebody who signs his
posts "PointedEars" bitching about supposed "real names".

How do you propose to tell the difference between "real" names and "fake"
names? If BartC signed his posts "Engelbert Humperdinck", "Cher", "Thomas
Lahn" or "Bartholomew Roberts" how would you decide whether it was "real"
or "fake"?

Petty bigotry over "real" names is no better than any other sort of bigotry.



-- 
Steven



From bc at freeuk.com  Thu Nov 12 17:19:59 2015
From: bc at freeuk.com (BartC)
Date: Thu, 12 Nov 2015 22:19:59 +0000
Subject: Question about math.pi is mutable
In-Reply-To: <10882952.phYABH7ckh@PointedEars.de>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
 <10882952.phYABH7ckh@PointedEars.de>
Message-ID: <n2336a$vq5$1@dont-email.me>

On 12/11/2015 20:40, Thomas 'PointedEars' Lahn wrote:
> Chris Angelico wrote:
>
>> [?] Ben Finney [?] wrote:
>>> I recommend you ignore that request; ?Bartc? is fine as a name here,
>>> IMO.
>>
>> Given that LARTC means Linux Advanced Routing and Traffic Control, I'm
>> guessing Bartc is all about *BSD networking? :)
>
> I thought LART were the Luser Attitude Readjustment Tool ;-)
>
> And on GABELNs [1] it is considered polite to post using your real name.
> Lack of politeness towards the people whom would otherwise be willing to
> help you may cause you to be ignored by them instead.  You have been warned.

I'm reading this 'list' on usenet. No-one else in many thousands of 
posts has ever complained before about my user-name.

But I guess you haven't been on that many forums. Few people use their 
full names or anything that looks like a real name. Partly, so they 
don't have someone who violently disagrees with them causing problems 
(like discovering their address and coming round).

Mostly people use names that are wacky, funny, or just meaningless.

(FWIW, my real first name is Bart and C is the initial of my last name. 
Very dull I know.)

-- 
bart c



From rosuav at gmail.com  Thu Nov 12 17:52:16 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 13 Nov 2015 09:52:16 +1100
Subject: Question about math.pi is mutable
In-Reply-To: <n2336a$vq5$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
 <10882952.phYABH7ckh@PointedEars.de> <n2336a$vq5$1@dont-email.me>
Message-ID: <CAPTjJmrravpeoD6stpc6ig5nDBEyo9HMjKezqT7zG8FExX+uHw@mail.gmail.com>

On Fri, Nov 13, 2015 at 9:19 AM, BartC <bc at freeuk.com> wrote:
> (FWIW, my real first name is Bart and C is the initial of my last name. Very
> dull I know.)

That's a common way of signing emails. I sign most of mine "ChrisA",
which (as you'll see from my headers) is constructed the same way. So
did the late Dave Angel (DaveA). Although I suppose I'm going to get
in trouble with PointedEars for not using my *full* name, but
abbreviating it to just "Chris".

ChrisA


From orgnut at yahoo.com  Thu Nov 12 18:59:33 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Thu, 12 Nov 2015 15:59:33 -0800
Subject: What is wrong in this example code?
In-Reply-To: <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>
References: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>
 <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>
Message-ID: <BJednVGxdfl7utjLnZ2dnUU7-K-dnZ2d@giganews.com>

On 11/12/2015 06:07 AM, fl wrote:
> On Thursday, November 12, 2015 at 8:58:33 AM UTC-5, fl wrote:
>> Hi,
>>
<snip>
>>      def tick(self):
>>          """ Time will be advanced by one second """
>>          if self.__seconds == 59:
>>              self.__seconds = 0
>>              if (self.__minutes == 59):
>>                  self.__minutes = 0
>>                  self.__hours = 0 if self.__hours==23  else self.__hours+1
>> 	    else:
>> 		self.__minutes += 1;
>> 	else:
>>              self.__seconds += 1;
<snip>

Nothing to do with your original question, just a trivial suggestion which you are free to 
ignore.  You can shorten this tick() method by using the divmod() function.  It does a division 
and returns both the quotient AND the remainder.  IOW, given divmod(x, y) it returns the tuple 
(x/y, x%y).  It is a very useful function.  Try this:

def tick(self):
     xtra, self._seconds = divmod(self._seconds + 1, 60)
     xtra, self._minutes = divmod(self._minutes + xtra, 60)
     self._hours += xtra

Explanation:  (to shorten this, I'm leaving off the leading "self._" from the actual code.)
The first divmod() sets xtra = (seconds+1) / 60, which is the 'overflow' if any, from the 
division by 60, and seconds is the updated seconds limited to 0-59 (the result of (seconds+1) % 
60).  The second divmod() does the same thing to update minutes (if xtra != 0) and xtra is set 
to the 'overflow' from that division, which is then added to hours.

More confusing perhaps, but definitely shorter.
As I said above, use it if you want or ignore it if it's too confusing.

      -=- Larry -=-



From nhilterbrand at gmail.com  Thu Nov 12 19:24:23 2015
From: nhilterbrand at gmail.com (Nathan Hilterbrand)
Date: Thu, 12 Nov 2015 19:24:23 -0500
Subject: What is wrong in this example code?
In-Reply-To: <BJednVGxdfl7utjLnZ2dnUU7-K-dnZ2d@giganews.com>
References: <1b204966-46c6-4890-a5a5-8addd20343a1@googlegroups.com>
 <383401eb-f8be-4f7a-bd63-3520eedc069e@googlegroups.com>
 <BJednVGxdfl7utjLnZ2dnUU7-K-dnZ2d@giganews.com>
Message-ID: <CADjZfm=kDYLRzVfwpk1mTvBFnXAe8VdPiXDEZ8CgfHL6bs3i2A@mail.gmail.com>

On Thu, Nov 12, 2015 at 6:59 PM, Larry Hudson via Python-list <
python-list at python.org> wrote:

Nothing to do with your original question, just a trivial suggestion which
> you are free to ignore.  You can shorten this tick() method by using the
> divmod() function.  It does a division and returns both the quotient AND
> the remainder.  IOW, given divmod(x, y) it returns the tuple (x/y, x%y).
> It is a very useful function.  Try this:
>
> def tick(self):
>     xtra, self._seconds = divmod(self._seconds + 1, 60)
>     xtra, self._minutes = divmod(self._minutes + xtra, 60)
>     self._hours += xtra
>
> Explanation:  (to shorten this, I'm leaving off the leading "self._" from
> the actual code.)
> The first divmod() sets xtra = (seconds+1) / 60, which is the 'overflow'
> if any, from the division by 60, and seconds is the updated seconds limited
> to 0-59 (the result of (seconds+1) % 60).  The second divmod() does the
> same thing to update minutes (if xtra != 0) and xtra is set to the
> 'overflow' from that division, which is then added to hours.
>
> More confusing perhaps, but definitely shorter.
> As I said above, use it if you want or ignore it if it's too confusing.
>
>      -=- Larry -=-
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>

Beat me to the punch.  I was about to suggest something similar, but I
thought that since one using this class would probably be "tick()-ing" more
than "str()-ing", It might also be better to store the value in seconds,
and convert to HH:MM:SS upon stringification; again using divmod:

class Clock(object):

    def __init__(self,hours=0,minutes=0,seconds=0):
        self.set(hours,minutes,seconds)

    def tick(self):
        self.__secs+=1

    def set(self,hours, minutes, seconds):
        self.__secs = seconds + (minutes*60) + (hours*60*60)

    def __str__(self):
        rest, seconds = divmod(self.__secs, 60)
        hours, minutes = divmod(rest, 60)

        return "%02d:%02d:%02d" % (hours, minutes, seconds)

    def display(self):
        print(str(self))


if __name__ == "__main__":

    x = Clock()
    print("Default construction, no parameters, Before ticks: {}".format(x))
    for i in range(10000):
        x.tick()
    print("After ticks: {}".format(x))

    x = Clock(hours=2, minutes=20, seconds=5)
    print("\nConstructor with hours=2, minutes=20, seconds=5: {}".format(x))

    print("Test of display() method: ",end=' ')
    x.display()


This is my first post here, and I am a Python n00b (coming from that
four-letter word language "p***"), so if I broke some top/bottom posting or
formatting rules, I apologize, and would appreciate any posting pointers

Nathan H.


From tundraBOGUS at tundraware.com  Thu Nov 12 19:25:35 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Thu, 12 Nov 2015 18:25:35 -0600
Subject: More tkinter Madness
In-Reply-To: <mailman.252.1447295160.16136.python-list@python.org>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
Message-ID: <v8nfhc-epd2.ln1@oceanview.tundraware.com>

On 11/11/2015 08:25 PM, Chris Angelico wrote:
> On Thu, Nov 12, 2015 at 12:52 PM, Tim Daneliuk
> <tundraBOGUS at tundraware.com> wrote:
>> I am the author of twander (https://www.tundraware.com/Software/twander).
>> This code has run flawlessly for years on FreeBSD, Linux, MacOS and
>> Windows.  Some months ago, I put it on a couple of VPS servers (FreeBSD
>> and Linux) and BOOM, it doesn't run.  I asked around here and got some
>> suggestions and then did some homework.
>>
>> Traceback (most recent call last):
>>   File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main
> 
> It's running here under Python 2.6. Sorry if this is a question you've
> already been asked, but were you successfully running under 2.6
> elsewhere? Might be a versioning issue.
> 
> ChrisA
> 

It always ran OK on every previous version of Python from about 2.4 forward
on VMs, physicals, *nix, OSX, Windows, etc.



From tundraBOGUS at tundraware.com  Thu Nov 12 19:26:42 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Thu, 12 Nov 2015 18:26:42 -0600
Subject: More tkinter Madness
In-Reply-To: <87oaf0q82t.fsf@nightsong.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <87oaf0q82t.fsf@nightsong.com>
Message-ID: <2bnfhc-epd2.ln1@oceanview.tundraware.com>

On 11/11/2015 08:12 PM, Paul Rubin wrote:
> Tim Daneliuk <tundraBOGUS at tundraware.com> writes:
>> Some months ago, I put it on a couple of VPS servers (FreeBSD
>> and Linux) and BOOM, it doesn't run.  I asked around here and got some
>> suggestions and then did some homework.
> 
> I'd expect a VPS server to have no display--is it an X client forward to
> your workstation?  Are all the proper X libraries installed?  Note that
> X port forwarding over the internet is generally unusable even if your
> internet connection is pretty fast.  It's kind of ok over a LAN.
> 

twander is a very, very ligthweight file browser with minimal GUI load.
It's always worked well even with X forwarded over an ssh session over the
open internet.

I will further investigate the X libs matter.


From abhishek.mallela at gmail.com  Thu Nov 12 20:54:28 2015
From: abhishek.mallela at gmail.com (Abhishek)
Date: Thu, 12 Nov 2015 17:54:28 -0800 (PST)
Subject: Matplotlib error: Value Error: x and y must have same first dimension
Message-ID: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>

I am trying to run some Python code for the last few hours. How can I achieve the effect of "dot divide" from Matlab, in the following code? I am having trouble working with list comprehension and numpy arrays and getting the following error:

    Traceback (most recent call last):
      File "Thurs.py", line 128, in <module>
        plt.plot(np.array(range(1,N/2+2)), Splot[alpha][iii,val]/utot[iii,val],color=cmap(iii/50))

    ValueError: x and y must have same first dimension

Code:

    import numpy as np
    import matplotlib as mpl
    import matplotlib.pyplot as plt
    from scipy.integrate import odeint
    
    N = 2
    K00 = np.logspace(3,5,101,10)
    len1 = len(K00)
    Qvec = np.logspace(-2,2,2,10)
    S10vec = np.logspace(2,6,2,10)
    len2 = len(Qvec)
    y0 = [0]*(3*N/2+3)
    Kplot = np.zeros((len1,len2))
    Pplot = np.zeros((len1,len2))
    S = [np.zeros((len1,len2)) for kkkk in range(N/2+1)]
    KS = [np.zeros((len1,len2)) for kkkk in range(N/2)]
    PS = [np.zeros((len1,len2)) for kkkk in range(N/2)]
    Splot = [np.zeros((len1,len2)) for kkkk in range(N/2+1)]
    KSplot = [np.zeros((len1,len2)) for kkkk in range(N/2)]
    PSplot = [np.zeros((len1,len2)) for kkkk in range(N/2)]
    
    for val in range(0,len2):
        for series in range(0,len1):
            K0 = K00[series]
            Q = Qvec[val]
            S10 = S10vec[val]
            r1 = 0.0001
            r2 = 0.001
            a = 0.001
            d = 0.001
            k = 0.999
            P0 = 1
            tfvec = [1e7, 1e10]
            tf = tfvec[val]
            time = np.linspace(0,tf,1001)
        
            def f(y,t):
                for alpha in range(0,(N/2+1)):
                    S[alpha] = y[alpha]
                for beta in range((N/2)+1,N+1):
                    KS[beta-N/2-1] = y[beta]
                for gamma in range(N+1,3*N/2+1):
                    PS[gamma-N-1] = y[gamma]
                K = y[3*N/2+1]
                P = y[3*N/2+2]
    
                ydot = np.zeros((3*N/2+3,1))
                B = range((N/2)+1,N+1)
                G = range(N+1,3*N/2+1)
                runsumPS = 0
                runsum1 = 0
                runsumKS = 0
                runsum2 = 0
    
                for m in range(0,N/2):
                    runsumPS = runsumPS + PS[m]
                    runsum1 = runsum1 + S[m+1]
                    runsumKS = runsumKS + KS[m]
                    runsum2 = runsum2 + S[m]
                    ydot[B[m]] = a*K*S[m]-(d+k+r1)*KS[m]
    
                for i in range(0,N/2-1):
                    ydot[G[i]] = a*P*S[i+1]-(d+k+r1)*PS[i]
    
                for p in range(1,N/2):
                    ydot[p] = -S[p]*(r1+a*K+a*P)+k*KS[p-1]+d*(PS[p-1]+KS[p])
    
                ydot[0] = Q-(r1+a*K)*S[0]+d*KS[0]+k*runsumPS
                ydot[N/2] = k*KS[N/2-1]-(r2+a*P)*S[N/2]+d*PS[N/2-1]
                ydot[G[N/2-1]] = a*P*S[N/2]-(d+k+r2)*PS[N/2-1]
                ydot[3*N/2+1] = (d+k+r1)*runsumKS-a*K*runsum2
                ydot[3*N/2+2] = (d+k+r1)*(runsumPS-PS[N/2-1])- \
                                a*P*runsum1+(d+k+r2)*PS[N/2-1]
    
                ydot_new = []
                for j in range(0,3*N/2+3):
                    ydot_new.extend(ydot[j])
                return ydot_new
            
            y0[0] = S10
            for i in range(1,3*N/2+1):
                y0[i] = 0
            y0[3*N/2+1] = K0
            y0[3*N/2+2] = P0
    
            soln = odeint(f,y0,time, mxstep = 5000)
            for alpha in range(0,(N/2+1)):
                S[alpha] = soln[:,alpha]
            for beta in range((N/2)+1,N+1):
                KS[beta-N/2-1] = soln[:,beta]
            for gamma in range(N+1,3*N/2+1):
                PS[gamma-N-1] = soln[:,gamma]
    
            for alpha in range(0,(N/2+1)):
                Splot[alpha][series,val] = soln[len(time)-1,alpha]
            for beta in range((N/2)+1,N+1):
                KSplot[beta-N/2-1][series,val] = soln[len(time)-1,beta]
            for gamma in range(N+1,3*N/2+1):
                PSplot[gamma-N-1][series,val] = soln[len(time)-1,gamma]
            
            u1 = 0
            u2 = 0
            u3 = 0
        
            for alpha in range(0,(N/2+1)):
                u1 = u1 + Splot[alpha]
            for beta in range((N/2)+1,N+1):
                u2 = u2 + KSplot[beta-N/2-1]
            for gamma in range(N+1,3*N/2+1):
                u3 = u3 + PSplot[gamma-N-1]
    
            K = soln[:,3*N/2+1]
            P = soln[:,3*N/2+2]
            Kplot[series] = soln[len1-1,3*N/2+1]
            Pplot[series] = soln[len1-1,3*N/2+2]
            utot = u1+u2+u3
    
        plt.figure(val)
        cmap = mpl.cm.autumn
        for iii in range(0,100,50):
            for alpha in range(0,(N/2+1)):
                plt.plot(np.array(range(1,N/2+2)), Splot[alpha][iii,val]/utot[iii,val],color=cmap(iii/50))
                plt.xlabel('i')
                plt.ylabel(r'$\frac{S_i}{S_{tot}}$ (nM)')
                plt.title('N = 20: Behavior at [S](0) = 10^' + str(log10(Qvec[val]) + 4) + '(nM)', fontsize=20)
        plt.show()

At the very least, can I extract the values that I need just for the plot?


From 18518281186 at 126.com  Thu Nov 12 22:08:27 2015
From: 18518281186 at 126.com (Xiang Zhang)
Date: Fri, 13 Nov 2015 11:08:27 +0800
Subject: What is the meaning of Py_INCREF a static PyTypeObject?
In-Reply-To: <CAEk9e3pP6H=6P68p6r0iNiPYh0HF9kGemTFTnPbyLf2Acx1wgg@mail.gmail.com>
References: <56444835.5020803@126.com>
 <CAEk9e3pP6H=6P68p6r0iNiPYh0HF9kGemTFTnPbyLf2Acx1wgg@mail.gmail.com>
Message-ID: <5645542B.9070602@126.com>

Thanks for your reply jason. Your reply does give me hints and then I 
read more code and find maybe you are wrong in some points.

I think the meaning of Py_INCREF a static type object is to prevent it 
from being deallocated when it is Py_DECREFed somehow later. Just as you 
said, it may be somehow deallocated when using.

NoddyType is a static struct so I don't think it lives on Python's heap 
and deallocating it is a wrong action. Just as I mentioned, type_dealloc 
seems to only deallocated HEAPTYPE. And by the way, when NoddyType is 
created, it has a reference count 1 with PyVarObject_HEAD_INIT. So if I 
don't Py_INCREF it, when it is somehow Py_DECREDed later, it will reach 
reference count 0 and fail the assert in type_dealloc. If it is 
Py_INCREFed, just like the module holds a reference to it, it will at 
least have a reference count 1 and never reach 0.

On 11/13/2015 02:52 AM, Jason Swails wrote:
>
>
> On Thu, Nov 12, 2015 at 3:05 AM, Xiang Zhang <18518281186 at 126.com 
> <mailto:18518281186 at 126.com>> wrote:
>
>     Recently I am learning Python C API.
>
>     When I read the tutorial
>     <https://docs.python.org/3/extending/newtypes.html#the-basics>,
>     defining new types, I feel confused. After
>     PyType_Ready(&noddy_NoddyType) comes Py_INCREF(&noddy_NoddyType).
>     Actually noddy_NoddyType is a static struct so I don't understand
>     why I need to Py_INCREF it. Since it's Py_INCREFed, does it mean
>     sometimes we also need to Py_DECREF it? But then it seems that
>     type_dealloc will be invoked and it will fail
>     assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);
>
>
> ?It is a module attribute, so when the module is imported it has to 
> have a single reference (the reference *in* the module).  If you don't 
> INCREF it, then it will have a refcount of 0, and immediately be ready 
> for garbage collection.  So if you try to use the type from the 
> module, you could get a segfault because it's trying to use an object 
> (type definition) that was already destroyed.
>
> Note that you don't *always* have to INCREF objects after you create 
> them in C.  Some macros and function do that for you. And in some 
> cases, all you want or need is a borrowed reference.  In those cases, 
> Py_INCREF is unnecessary.
>
> The DECREF will be done when it's normally done in Python.  If you do 
> something like
>
> import noddy
> del noddy.NoddyType
>
> ?All that's really doing is removing NoddyType from the noddy 
> namespace and Py_DECREFing it.  Alternatively, doing
>
> import noddy
> noddy.NoddyType = 10 # rebind the name
>
> Then the original object NoddyType was pointing to will be DECREFed 
> and NoddyType will point to an object taking the value of 10.
>
> HTH,
> Jason



From tjreedy at udel.edu  Thu Nov 12 22:32:35 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 12 Nov 2015 22:32:35 -0500
Subject: Is it useful for re.M in this example?
In-Reply-To: <fc8a4061-5156-41c8-bfd7-d9a8da462418@googlegroups.com>
References: <fc8a4061-5156-41c8-bfd7-d9a8da462418@googlegroups.com>
Message-ID: <n23lkm$fgl$1@ger.gmane.org>

On 11/12/2015 4:34 PM, fl wrote:

> I follow a web site on learning Python re. I have read the function
>   description of re.m, as below.

> re.M	Makes $ match the end of a line (not just the end of the string) and
>   makes ^ match the start of any line (not just the start of the string).
>
> But I don't see the reason to put re.M in the example project:
>
> #!/usr/bin/python
> import re
>
> line = "Cats are smarter than dogs";
>
> matchObj = re.match( r'dogs', line, re.M|re.I)
> if matchObj:
>     print "match --> matchObj.group() : ", matchObj.group()
> else:
>     print "No match!!"
>
> The tutorial (http://www.tutorialspoint.com/python/python_reg_expressions.htm)
> is for a beginner as I. Is there something I don't see in the example?

No. The use of re.M in the examples is doubly irrelevant since there is 
no \n in line and no $ in the pattern.  Re.I is also not relevant since 
there is no case-insensitive matchin.  It appears that the author 
routinely uses flags=re.M|re.I.  For a tutorial, I would have omitted 
either omitted them or explained them as routine boilerplate.

-- 
Terry Jan Reedy



From torriem at gmail.com  Thu Nov 12 23:46:18 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 12 Nov 2015 21:46:18 -0700
Subject: More tkinter Madness
In-Reply-To: <v8nfhc-epd2.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
Message-ID: <56456B1A.6080503@gmail.com>

On 11/12/2015 05:25 PM, Tim Daneliuk wrote:
> On 11/11/2015 08:25 PM, Chris Angelico wrote:
>> On Thu, Nov 12, 2015 at 12:52 PM, Tim Daneliuk
>> <tundraBOGUS at tundraware.com> wrote:
>>> I am the author of twander (https://www.tundraware.com/Software/twander).
>>> This code has run flawlessly for years on FreeBSD, Linux, MacOS and
>>> Windows.  Some months ago, I put it on a couple of VPS servers (FreeBSD
>>> and Linux) and BOOM, it doesn't run.  I asked around here and got some
>>> suggestions and then did some homework.
>>>
>>> Traceback (most recent call last):
>>>   File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main
>>
>> It's running here under Python 2.6. Sorry if this is a question you've
>> already been asked, but were you successfully running under 2.6
>> elsewhere? Might be a versioning issue.
>>
>> ChrisA
>>
> 
> It always ran OK on every previous version of Python from about 2.4 forward
> on VMs, physicals, *nix, OSX, Windows, etc.

And other X11 apps are working fine on the test VPS where your app
crashes? Other Tk apps?  Other Python Tk apps?

Your app runs fine on my VPS (Linode), running CentOS 7, Python 2.7.
Also runs fine on my CentOS 6 VM (also Linode), Python 2.6.6.

I also verified that if X11 forwarding is not working, Python reports an
exception "_tkinter.TclError: no display name and no $DISPLAY
environment variable" immediately, so that's definitely not your problem.





From karthik.sharma at gmail.com  Fri Nov 13 00:27:58 2015
From: karthik.sharma at gmail.com (Karthik Sharma)
Date: Thu, 12 Nov 2015 21:27:58 -0800 (PST)
Subject: Plotting timeseries from a csv file using matplotlib
Message-ID: <d52cd13c-25e4-4393-8eff-6910c7394f17@googlegroups.com>

I have some csv data in the following format.

Ln	Dr	Tag	 Lab	   0:01   0:02  0:03  0:04   0:05  0:06  0:07  0:08  0:09	
L0	St  	 vT	 4R	     0	       0	 0	  0	    0      0	     0	      0       0		
L2	Tx 	 st	 4R	     8	       8	 8	  8	    8	    8	     8	      8       8	
L2	Tx 	 ss	 4R	     1	       1	 9	  6	    1	    0	     0	      6       7	

I want to plot a timeseries graph using the columns (`Ln` , `Dr`, `Tg`,`Lab`) as the keys and the `0:0n ` field as values on a timeseries graph.I want all the timeseries to be plotted on a single timeseries? 

I have the following code.

    #!/usr/bin/env python

    import matplotlib.pyplot as plt 
    import datetime
    import numpy as np
    import csv 
    import sys 
    
    
    with open("test.csv", 'r', newline='') as fin:
        reader = csv.DictReader(fin)
        for row in reader:
              key = (row['Ln'], row['Dr'], row['Tg'],row['Lab'])
              #code to extract the values and plot a timeseries.                                                                                                                                                                             
    ~  

How do I extract all the values in columns `0:0n` without induviduall specifying each one of them. 
                            


From tundraBOGUS at tundraware.com  Fri Nov 13 00:42:38 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Thu, 12 Nov 2015 23:42:38 -0600
Subject: More tkinter Madness
In-Reply-To: <mailman.283.1447389990.16136.python-list@python.org>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
Message-ID: <fr9ghc-c5i2.ln1@oceanview.tundraware.com>

On 11/12/2015 10:46 PM, Michael Torrie wrote:
> On 11/12/2015 05:25 PM, Tim Daneliuk wrote:
>> On 11/11/2015 08:25 PM, Chris Angelico wrote:
>>> On Thu, Nov 12, 2015 at 12:52 PM, Tim Daneliuk
>>> <tundraBOGUS at tundraware.com> wrote:
>>>> I am the author of twander (https://www.tundraware.com/Software/twander).
>>>> This code has run flawlessly for years on FreeBSD, Linux, MacOS and
>>>> Windows.  Some months ago, I put it on a couple of VPS servers (FreeBSD
>>>> and Linux) and BOOM, it doesn't run.  I asked around here and got some
>>>> suggestions and then did some homework.
>>>>
>>>> Traceback (most recent call last):
>>>>   File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main
>>>
>>> It's running here under Python 2.6. Sorry if this is a question you've
>>> already been asked, but were you successfully running under 2.6
>>> elsewhere? Might be a versioning issue.
>>>
>>> ChrisA
>>>
>>
>> It always ran OK on every previous version of Python from about 2.4 forward
>> on VMs, physicals, *nix, OSX, Windows, etc.
> 
> And other X11 apps are working fine on the test VPS where your app
> crashes? Other Tk apps?  Other Python Tk apps?
> 
> Your app runs fine on my VPS (Linode), running CentOS 7, Python 2.7.
> Also runs fine on my CentOS 6 VM (also Linode), Python 2.6.6.
> 
> I also verified that if X11 forwarding is not working, Python reports an
> exception "_tkinter.TclError: no display name and no $DISPLAY
> environment variable" immediately, so that's definitely not your problem.
> 
> 
> 

Curioser and curioser.  Yes, xterm works fine.  Dunno about any other tk apps.
Hmmmm..


From auriocus at gmx.de  Fri Nov 13 01:32:08 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Fri, 13 Nov 2015 07:32:08 +0100
Subject: More tkinter Madness
In-Reply-To: <fr9ghc-c5i2.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com>
Message-ID: <n2400v$h96$1@dont-email.me>

Am 13.11.15 um 06:42 schrieb Tim Daneliuk:
>
> Curioser and curioser.  Yes, xterm works fine.  Dunno about any other tk apps.

Hello world Tk is like this:

Apfelkiste:Sources chris$ wish
% pack [button .b -text Hello -command exit]
% Apfelkiste:Sources chris$

Upon starting wish, an empty window should appear. The single line makes 
a button, which exits the program when pressed.

It is very strange in your Traceback, that the TclError is not 
accompanyied by an actual error. This indicates that something more 
fundamental is going wrong. It seems to crash upon "import tkinter"; can 
you try reinstalling all related packages?

	Christian


From lac at openend.se  Fri Nov 13 03:34:23 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 09:34:23 +0100
Subject: Matplotlib error: Value Error: x and y must have same first
 dimension
In-Reply-To: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>
References: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>
Message-ID: <201511130834.tAD8YNra005833@fido.openend.se>

In a message of Thu, 12 Nov 2015 17:54:28 -0800, Abhishek writes:
>I am trying to run some Python code for the last few hours. How can I achieve the effect of "dot divide" from Matlab, in the following code? I am having trouble working with list comprehension and numpy arrays and getting the following error:
>
>    Traceback (most recent call last):
>      File "Thurs.py", line 128, in <module>
>        plt.plot(np.array(range(1,N/2+2)), Splot[alpha][iii,val]/utot[iii,val],color=cmap(iii/50))
>
>    ValueError: x and y must have same first dimension

Splot is a list.  matplotlib wants 2 numpy arrays.  You have to cast
it with np.array() too.

no guarantees that the rest of the code works -- it is not plotting for
me -- but that gets rid of that error at any rate.

Laura


From mjoerg.phone at gmail.com  Fri Nov 13 03:56:03 2015
From: mjoerg.phone at gmail.com (PythonDude)
Date: Fri, 13 Nov 2015 00:56:03 -0800 (PST)
Subject: don't understand matrix-multiplication should be reversed in
 python?
In-Reply-To: <mailman.275.1447346115.16136.python-list@python.org>
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
 <mailman.275.1447346115.16136.python-list@python.org>
Message-ID: <e700b1b8-50fd-41a2-a96f-f0b2d7343c85@googlegroups.com>

On Thursday, 12 November 2015 17:35:39 UTC+1, Ian  wrote:
> On Thu, Nov 12, 2015 at 8:57 AM, PythonDude <xxx....com> wrote:
> > Hi all,
> > Anyone could please explain or elaborate on exactly this (quote): "Keep in mind that Python has a reversed definition of rows and columns"???
> >
> > That I don't understand - thank you for any hints/guidance/explanations/ideas/suggestions etc!
> 
> py> import numpy
> py> p = numpy.reshape(range(5), (5,1))
> py> p
> array([[0],
>        [1],
>        [2],
>        [3],
>        [4]])
> py> p.T
> array([[0, 1, 2, 3, 4]])
> py> p.dot(p.T)
> array([[ 0,  0,  0,  0,  0],
>        [ 0,  1,  2,  3,  4],
>        [ 0,  2,  4,  6,  8],
>        [ 0,  3,  6,  9, 12],
>        [ 0,  4,  8, 12, 16]])
> py> p.T.dot(p)
> array([[30]])
> py> m = numpy.asmatrix(p)
> py> m
> matrix([[0],
>         [1],
>         [2],
>         [3],
>         [4]])
> py> m.T
> matrix([[0, 1, 2, 3, 4]])
> py> m * m.T
> matrix([[ 0,  0,  0,  0,  0],
>         [ 0,  1,  2,  3,  4],
>         [ 0,  2,  4,  6,  8],
>         [ 0,  3,  6,  9, 12],
>         [ 0,  4,  8, 12, 16]])
> py> m.T * m
> matrix([[30]])
> 
> Yeah, I don't know what that person is talking about either. It looks
> correct to me.

Thank you very much, Ian - just had to be sure about this - I would also be very disappointed in Python, if this author was right about this non-intuitive interpretation of how to do matrix multiplication :-)


From mjoerg.phone at gmail.com  Fri Nov 13 03:57:06 2015
From: mjoerg.phone at gmail.com (PythonDude)
Date: Fri, 13 Nov 2015 00:57:06 -0800 (PST)
Subject: don't understand matrix-multiplication should be reversed in
 python?
In-Reply-To: <mailman.280.1447365421.16136.python-list@python.org>
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
 <mailman.280.1447365421.16136.python-list@python.org>
Message-ID: <11344ffd-f594-4059-8c41-6bacbdb66f10@googlegroups.com>

On Thursday, 12 November 2015 22:57:21 UTC+1, Robert Kern  wrote:
> On 2015-11-12 15:57, PythonDude wrote:
> > Hi all,
> >
> > I've come around a webpage with python-tutorial/description for obtaining something and I'll solve this:
> >
> > R = p^T w
> >
> > where R is a vector and p^T is the transpose of another vector.
> >
> > ...
> > p is a Nx1 column vector, so p^T turns into a 1xN row vector which can be multiplied with the
> > Nx1 weight (column) vector w to give a scalar result. This is equivalent to the dot
> > product used in the code. Keep in mind that Python has a reversed definition of
> > rows and columns and the accurate NumPy version of the previous equation would
> > be R = w * p.T
> > ...
> >
> > (source: http://blog.quantopian.com/markowitz-portfolio-optimization-2/ )
> >
> > I don't understand this: "Keep in mind that Python has a reversed definition of
> > rows and columns and the accurate NumPy version of the previous equation would
> > be R = w * p.T"
> >
> > Not true for numpy, is it? This page: http://mathesaurus.sourceforge.net/matlab-numpy.html says it python and matlab looks quite similar...
> >
> > Anyone could please explain or elaborate on exactly this (quote): "Keep in mind that Python has a reversed definition of rows and columns"???
> 
> He's wrong, simply put. There is no "reversed definition of rows and columns". 

Great, thank...

> He simply instantiated the two vectors as row-vectors instead of column-vectors, 
> which he could have easily done, so he had to flip the matrix expression.

Thank you very much Robert - I just had to be sure about it :-)


From animsri13 at gmail.com  Fri Nov 13 04:17:12 2015
From: animsri13 at gmail.com (Animesh Srivastava)
Date: Fri, 13 Nov 2015 14:47:12 +0530
Subject: No subject
Message-ID: <CAHJN_b1W-fypzV1xWmcsmE6nnQh3gZnwZLBT=+7sZE9YmgkzKg@mail.gmail.com>

Whenever i install python 3.5.0 compiler
It gives me error 0x000007b
Can u please resolve it


From denismfmcmahon at gmail.com  Fri Nov 13 04:19:32 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Fri, 13 Nov 2015 09:19:32 -0000 (UTC)
Subject: Question about math.pi is mutable
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
 <10882952.phYABH7ckh@PointedEars.de>
 <56450d07$0$1584$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n249v4$f8n$1@dont-email.me>

On Fri, 13 Nov 2015 09:04:54 +1100, Steven D'Aprano wrote:

> On Fri, 13 Nov 2015 07:40 am, Thomas 'PointedEars' Lahn wrote:

> > [crap I expect]

> And you should consider the irony, and hypocrisy, of somebody who signs
> his posts "PointedEars" bitching about supposed "real names".

TPEL has been trolling html, php and javascript newsgroups for years, 
recently he seems to have discovered python newsgroups. :(

-- 
Denis McMahon, denismfmcmahon at gmail.com


From chris at chrullrich.net  Fri Nov 13 05:52:01 2015
From: chris at chrullrich.net (Christian Ullrich)
Date: Fri, 13 Nov 2015 11:52:01 +0100
Subject: Running latest 32-bit Python on 64-bit system
Message-ID: <daltmhFas7qU1@mid.individual.net>

Hello,

I have a problem with using the (otherwise nice) Python launcher. How 
can I get it to run the highest 32-bit Python on my 64-bit system? This 
is on Windows, but I think it applies to other OSes as well.

My application runs (unmodified) with Python 3.[345], but only with the 
32-bit version because it loads a DLL that has no 64-bit version 
available. I would like to run it on any system that has *any* suitable 
Python installed.

However, with the shebang syntax supported by the launcher, I can only 
demand a 32-bit version if I also specify the Python minor version I 
want, and I don't necessarily know that in advance.

I can code around that, of course, but I don't want to. If Python can 
select the 64-bit version to run by itself, it should also be able to 
for the 32-bit version, right?

Thanks,

-- 
Christian


From fabien.maussion at gmail.com  Fri Nov 13 06:51:45 2015
From: fabien.maussion at gmail.com (Fabien)
Date: Fri, 13 Nov 2015 12:51:45 +0100
Subject: Plotting timeseries from a csv file using matplotlib
References: <d52cd13c-25e4-4393-8eff-6910c7394f17@googlegroups.com>
Message-ID: <n24isg$u08$1@speranza.aioe.org>

On 11/13/2015 06:27 AM, Karthik Sharma wrote:
> How do I extract all the values in columns

Have a look at pandas: 
http://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_csv.html


From vmt.eiz at gmail.com  Fri Nov 13 07:23:41 2015
From: vmt.eiz at gmail.com (Akshat Tripathi)
Date: Fri, 13 Nov 2015 04:23:41 -0800 (PST)
Subject: Unable to make http request to django server using
 twisted.web.client.AGENT
In-Reply-To: <ac674dfd-7da1-4f47-8a13-ba3c4128d89b@googlegroups.com>
References: <ac674dfd-7da1-4f47-8a13-ba3c4128d89b@googlegroups.com>
Message-ID: <64221fbe-7c1a-4994-843a-abc1a21c5dab@googlegroups.com>

On Thursday, 5 November 2015 13:06:13 UTC+5:30, Akshat Tripathi  wrote:
> I have written a basic tcp server factory, server client and a service using twisted. The tcp server acts as the middleware between a django server and an another program (let's call it client program).
> 
> What I want to achieve -
> 
> 1.client requests the middleware tcp server;
> 
> 2.it sends a string as the request body;
> 
> 3.the middleware tcp server deserializes information from the request.
> 
> 4.middleware furthers the serialized information to the django server.
> 
> 5.The django server then responds to the middleware server which furthers the response to the client after serializing the response.
> 
> I am able to reach till step 3, but am unable to make any http request to the django server.
> 
> 
> 
> 
> The following is my middleware.py
> 
> from twisted.internet.protocol import ServerFactory
> from twisted.internet.protocol import Protocol
> 
> from test_service import MyService
> 
> 
> class TCPServerProtocol(Protocol):
>     data = ''
> 
>     def connectionMade(self):
>         self.deferred = self.factory.service.deferred
>         self.deferred.addCallback(self.factory.service.s)
>         self.deferred.addCallback(self.transport.write)
>         self.deferred.addBoth(lambda r: self.transport.loseConnection)
> 
>     def dataReceived(self, data):
>         self.data += data
> 
>     def connectionLost(self, reason):
>         self.forward(self.data)
> 
>     def forward(self, data):
>         if self.deferred is not None:
>             d, self.deferred = self.deferred, None
>             d.callback(data)
> 
> class TCPServerFactory(ServerFactory):
> 
>     protocol = TCPServerProtocol
> 
>     def __init__(self, service):
>         self.service = service
> 
> def runserver(ip, port):
>     iface =  {'home': '192.168.0.104', 'work': '127.0.0.1'}
>     service = MyService()
>     factory = TCPServerFactory(service)
>     from twisted.internet import reactor
>     reactor.listenTCP(port=port, factory=factory, interface=iface[ip])
>     reactor.run()
> 
> if __name__ == '__main__':
>     import sys
>     ip = sys.argv[1]
>     port = int(sys.argv[2])
>     runserver(ip, port)
> 
> 
> 
> 
> The following is test_service.py
> 
> from twisted.internet.defer import Deferred
> 
> from test_http_client import HTTPClientFactory
> 
> class MyService(object):
>     def __init__(self):
>         self.deferred = Deferred()
> 
>     def s(self, data):
>         kwargs = {}
>         kwargs['url'] = b'http://127.0.0.1:8000/some/end/point'
>         kwargs['url'] = kwargs['url'].encode('latin-1')
>         kwargs['method'] = 'POST'
>         kwargs['data'] = data
> 
>         client = HTTPClientFactory(**kwargs)
>         d = client.deferred
>         return d
> 
> 
> The following is test_http_client.py
> 
> from StringIO import StringIO
> import json
> 
> from twisted.internet.protocol import Protocol
> from twisted.internet.defer import Deferred
> from twisted.web.client import Agent, FileBodyProducer
> from twisted.web.http_headers import Headers
> 
> 
> class HTTPClientProtocol(Protocol):
>     def __init__(self, finished):
>         self.finished = finished
>         self.data = ''
> 
>     def dataReceived(self, data):
>         print '----------Data Received by HTTPClientProtocol----------'
>         print data
>         self.data += data
> 
>     def connectionLost(self, reason):
>         print '----------HTTP Client connection Lost----------'
>         print reason.getErrorMessage()
>         if self.finished is not None:
>             print 'finished is not None'
>             f, self.finished = self.finished, None
>             f.callback(self.data)
> 
> class HTTPClientFactory(object):
> 
>     """
>     Class handling communication with HTTP server.
>     """
> 
>     def __init__(self, **kwargs):
>         data = kwargs['data'] 
>         try:
>             body = FileBodyProducer(StringIO(json.dumps(data)))
>             print '----------Request body object created----------'
>         except Exception as e:
>             print '----------Request body object creation FAILURE----------'
>             print e
>             return e  
>         url = kwargs.get('url', None)
>         method = kwargs.get('method', None)
> 
>         from twisted.internet import reactor
>         agent = Agent(reactor)
>         if not data:
>             body = None
> 
>         self.deferred = agent.request(method,
>                                     url,
>                                     Headers({'Content-Type': ['application/json']}),
>                                     bodyProducer=body)
> 
>         self.deferred.addCallback(self.get_response)
> 
>     def get_response(self, response):
>         print 'Response received'
>         finished = Deferred()
>         response.deliverBody(HTTPClientProtocol(finished))
>         return finished

Found the bug. Below is the corrected code.

class TCPServerProtocol(Protocol):

    # data = ''

    def connectionMade(self):
        self.deferred = self.factory.service.deferred
        self.deferred.addCallback(self.factory.service.s)
        self.deferred.addCallback(self.transport.write)
        self.deferred.addBoth(lambda r: self.transport.loseConnection)

    def dataReceived(self, data):
        self.data = data           # instead of self.data += data
        self.forward(self.data)    # this is the right place to call this method which in turn fires the callback through which the request is made to the server.

    def connectionLost(self, reason): pass
        # this will not be called until the connection from client is ended. 
        # self.forward(self.data)

    def forward(self, data):
        if self.deferred is not None:
            d, self.deferred = self.deferred, None
            d.callback(data)


From rosuav at gmail.com  Fri Nov 13 08:17:03 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 00:17:03 +1100
Subject: No subject
In-Reply-To: <CAHJN_b1W-fypzV1xWmcsmE6nnQh3gZnwZLBT=+7sZE9YmgkzKg@mail.gmail.com>
References: <CAHJN_b1W-fypzV1xWmcsmE6nnQh3gZnwZLBT=+7sZE9YmgkzKg@mail.gmail.com>
Message-ID: <CAPTjJmr3QDyPUxfkXErYyEJgHb6GFuuhzPj4ASuVOWusVDWq4w@mail.gmail.com>

On Fri, Nov 13, 2015 at 8:17 PM, Animesh Srivastava <animsri13 at gmail.com> wrote:
> Whenever i install python 3.5.0 compiler
> It gives me error 0x000007b
> Can u please resolve it

Is this Windows XP? You have three options:

1) Install Python 3.4 instead
2) Upgrade to a newer Windows
3) Upgrade to a better operating system

Is this not Windows XP? You have three options:

1) Read about newsgroup postings and subject lines
2) Resolve the issue yourself, with the skills you have
3) Tell us a *lot* more information about what's going on, what OS
you're using (including the version), the error message you're
getting, etc, etc.

In each case, the third option is the best by far, and is recommended.

ChrisA


From rxjwg98 at gmail.com  Fri Nov 13 08:50:19 2015
From: rxjwg98 at gmail.com (fl)
Date: Fri, 13 Nov 2015 05:50:19 -0800 (PST)
Subject: Can Canopy Express (Free) allow install a new package (PyBayes) to it?
Message-ID: <9d801f2d-06d3-41c7-9f56-d029567b912a@googlegroups.com>

I am using Canopy Express (Free) version. I want to install PyBayes package,
 but I don't see it in Package Manager of Canopy. Can I install PyBayes to
 Canopy?

Now, Canopy is the default Python on my Windows 7 PC. If Canopy does not allow
 to install PyBayes into it, can I install PyBayes to the plain Python 2.7
 (downloaded from Python website, which was installed before I installed
 Canopy), and use Python 2.7 IDLE with PyBayes? (I am concern about  Canopy
 makes the Windows Python 2.7 not the same way as before?

Thanks,


From oscar.j.benjamin at gmail.com  Fri Nov 13 09:04:01 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Fri, 13 Nov 2015 14:04:01 +0000
Subject: Matplotlib error: Value Error: x and y must have same first
 dimension
In-Reply-To: <201511130834.tAD8YNra005833@fido.openend.se>
References: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>
 <201511130834.tAD8YNra005833@fido.openend.se>
Message-ID: <CAHVvXxQVs7O8K7cCiya7=yovwxHAdPoPZh6CQV4hsMEFroBYLA@mail.gmail.com>

On 13 November 2015 at 08:34, Laura Creighton <lac at openend.se> wrote:
> In a message of Thu, 12 Nov 2015 17:54:28 -0800, Abhishek writes:
>>I am trying to run some Python code for the last few hours. How can I achieve the effect of "dot divide" from Matlab, in the following code? I am having trouble working with list comprehension and numpy arrays and getting the following error:
>>
>>    Traceback (most recent call last):
>>      File "Thurs.py", line 128, in <module>
>>        plt.plot(np.array(range(1,N/2+2)), Splot[alpha][iii,val]/utot[iii,val],color=cmap(iii/50))
>>
>>    ValueError: x and y must have same first dimension
>
> Splot is a list.  matplotlib wants 2 numpy arrays.  You have to cast
> it with np.array() too.

Actually the plot command is perfectly happy converting lists or lists
of lists etc. to arrays (by calling np.array internally) so you don't
need to convert any of your inputs. By the way: np.arange(1, N/2+2)
would be the usual way to create a numpy array that is a range.

The error here comes because (after both arguments are converted to
arrays) they have incompatible sizes. In other words:

    len(range(1,N/2+2)) != len(Splot[alpha][iii,val]/utot[iii,val])

I'm not sure what the solution is as the code is too complex for me to
spend time trying to guess what it's trying to do.

--
Oscar


From denismfmcmahon at gmail.com  Fri Nov 13 09:32:38 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Fri, 13 Nov 2015 14:32:38 -0000 (UTC)
Subject: Plotting timeseries from a csv file using matplotlib
References: <d52cd13c-25e4-4393-8eff-6910c7394f17@googlegroups.com>
Message-ID: <n24sa6$f8n$2@dont-email.me>

On Thu, 12 Nov 2015 21:27:58 -0800, Karthik Sharma wrote:

> I have some csv data in the following format. ......

Does the following idea help?

Create a key from the key fields, remove the key fields from the row dic 
(so now it's a dic of just the data fields), and save that in the 
plotdata dict keyed by the key.

import csv

keybits = ["Ln","Dr","Tag","Lab"]

plotdata = {}

with open("lab.csv", 'r') as fin:
    reader = csv.DictReader(fin)
    for row in reader:
        key = tuple([row[k] for k in keybits])
        for k in keybits:
            del row[k]
        plotdata[key] = row

This generates a dictionary (plotdata) keyed by the key tuples where the 
value for each key is a dictionary of 0:0n : value

-- 
Denis McMahon, denismfmcmahon at gmail.com


From oscar.j.benjamin at gmail.com  Fri Nov 13 09:59:41 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Fri, 13 Nov 2015 14:59:41 +0000
Subject: What is the meaning of Py_INCREF a static PyTypeObject?
In-Reply-To: <5645542B.9070602@126.com>
References: <56444835.5020803@126.com>
 <CAEk9e3pP6H=6P68p6r0iNiPYh0HF9kGemTFTnPbyLf2Acx1wgg@mail.gmail.com>
 <5645542B.9070602@126.com>
Message-ID: <CAHVvXxTxyG0V5rjKjaFH6X_KCYa0=WkzMU2Cpu17k5DxH44Wcw@mail.gmail.com>

On 13 November 2015 at 03:08, Xiang Zhang <18518281186 at 126.com> wrote:
> I think the meaning of Py_INCREF a static type object is to prevent it from
> being deallocated when it is Py_DECREFed somehow later. Just as you said, it
> may be somehow deallocated when using.
>
> NoddyType is a static struct so I don't think it lives on Python's heap and
> deallocating it is a wrong action. Just as I mentioned, type_dealloc seems
> to only deallocated HEAPTYPE. And by the way, when NoddyType is created, it
> has a reference count 1 with PyVarObject_HEAD_INIT. So if I don't Py_INCREF
> it, when it is somehow Py_DECREDed later, it will reach reference count 0
> and fail the assert in type_dealloc. If it is Py_INCREFed, just like the
> module holds a reference to it, it will at least have a reference count 1
> and never reach 0.

Other code shouldn't Py_DECREF it unless it owns a reference meaning
that it has first called Py_INCREF. The only exception I can think is
possibly that someone would do:

    >>> import noddy
    >>> del noddy.Noddy

For that to work properly I guess that Noddy needs a reference count
of 2: one for being a module attribute and an extra one to prevent it
from ever being deallocated.

--
Oscar


From mjoerg.phone at gmail.com  Fri Nov 13 10:37:55 2015
From: mjoerg.phone at gmail.com (PythonDude)
Date: Fri, 13 Nov 2015 07:37:55 -0800 (PST)
Subject: numpy column_stack - why does this work?
Message-ID: <0b4725a8-a040-4bfb-b046-81c2e529447a@googlegroups.com>

Hi all,

Just a quick question about this code-piece (it works, I've tested it):

means, stds = np.column_stack([
    getMuSigma_from_PF(return_vec) 
    for _ in xrange(n_portfolios) ])


1) I understand column_stack does this (assembles vectors vertically, side-by-side):

>>> a = np.array((1,2,3)) # NB: a is row-vector: {1 2 3}
>>> b = np.array((2,3,4)) # NB: b is also a row-vector...
>>> np.column_stack((a,b))
array([[1, 2],
       [2, 3],
       [3, 4]])

2) I understand the underscore is just a "dummy variable" in the last line "for _ in xrange(n_portfolios)" - this also looked a bit confusing to me, at first...

3) I DON'T understand why the code doesn't look like this:

means, stds = np.column_stack([
    for _ in xrange(n_portfolios):
      getMuSigma_from_PF(return_vec) ])

???

Any comments/advice/hints, I would appreciate from you, thank you!


From lac at openend.se  Fri Nov 13 10:40:02 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 16:40:02 +0100
Subject: No subject
In-Reply-To: <CAHJN_b1W-fypzV1xWmcsmE6nnQh3gZnwZLBT=+7sZE9YmgkzKg@mail.gmail.com>
References: <CAHJN_b1W-fypzV1xWmcsmE6nnQh3gZnwZLBT=+7sZE9YmgkzKg@mail.gmail.com>
Message-ID: <201511131540.tADFe2n2006181@fido.openend.se>

In a message of Fri, 13 Nov 2015 14:47:12 +0530, Animesh Srivastava writes:
>Whenever i install python 3.5.0 compiler
>It gives me error 0x000007b
>Can u please resolve it
>-- 
>https://mail.python.org/mailman/listinfo/python-list

Maybe this is your problem
http://www.bitdefender.com/support/how-to-solve-error-message-%22the-application-was-unable-to-start-correctly-%280x000007b%29-click-ok-to-close-the-application%22-1106.html

Laura


From lac at openend.se  Fri Nov 13 10:43:54 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 16:43:54 +0100
Subject: Matplotlib error: Value Error: x and y must have same first
 dimension
In-Reply-To: <CAHVvXxQVs7O8K7cCiya7=yovwxHAdPoPZh6CQV4hsMEFroBYLA@mail.gmail.com>
References: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>
 <201511130834.tAD8YNra005833@fido.openend.se>
 <CAHVvXxQVs7O8K7cCiya7=yovwxHAdPoPZh6CQV4hsMEFroBYLA@mail.gmail.com>
Message-ID: <201511131543.tADFhsvL006539@fido.openend.se>

In a message of Fri, 13 Nov 2015 14:04:01 +0000, Oscar Benjamin writes:
>On 13 November 2015 at 08:34, Laura Creighton <lac at openend.se> wrote:
>> In a message of Thu, 12 Nov 2015 17:54:28 -0800, Abhishek writes:
>>>I am trying to run some Python code for the last few hours. How can I achieve the effect of "dot divide" from Matlab, in the following code? I am having trouble working with list comprehension and numpy arrays and getting the following error:
>>>
>>>    Traceback (most recent call last):
>>>      File "Thurs.py", line 128, in <module>
>>>        plt.plot(np.array(range(1,N/2+2)), Splot[alpha][iii,val]/utot[iii,val],color=cmap(iii/50))
>>>
>>>    ValueError: x and y must have same first dimension
>>
>> Splot is a list.  matplotlib wants 2 numpy arrays.  You have to cast
>> it with np.array() too.
>
>Actually the plot command is perfectly happy converting lists or lists
>of lists etc. to arrays (by calling np.array internally) so you don't
>need to convert any of your inputs. By the way: np.arange(1, N/2+2)
>would be the usual way to create a numpy array that is a range.
>
>The error here comes because (after both arguments are converted to
>arrays) they have incompatible sizes. In other words:
>
>    len(range(1,N/2+2)) != len(Splot[alpha][iii,val]/utot[iii,val])
>
>I'm not sure what the solution is as the code is too complex for me to
>spend time trying to guess what it's trying to do.
>
>--
>Oscar

I am sorry for the bad information.  Thank you Oscar.

Laura


From Cecil at decebal.nl  Fri Nov 13 11:33:06 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Fri, 13 Nov 2015 17:33:06 +0100
Subject: Trying out Kivy
Message-ID: <871tbt3lml.fsf@Equus.decebal.nl>

I tried out the ?standard? Kivy application:
============================================================
from kivy.app import App
from kivy.uix.button import Button

class TestApp(App):
    def build(self):
        return Button(text='Hello World')

TestApp().run()
============================================================

When using python2 I see some exceptions and OSErrors, but it runs.

When using python3 I get:
    [CRITICAL          ] [Text        ] Unable to find any valuable Text provider at all!
    pygame - ImportError: No module named 'pygame'
      File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
        fromlist=[modulename], level=0)
      File "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pygame.py", line 12, in <module>
        import pygame

    pil - ImportError: No module named 'PIL'
      File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
        fromlist=[modulename], level=0)
      File "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pil.py", line 8, in <module>
        from PIL import Image, ImageFont, ImageDraw

    [CRITICAL          ] [App         ] Unable to get a Text provider, abort.

I tried to install pygame and PIL with pip3, but that did not find
anything. Is there another way to install those dependencies?

But more importantly: can I develop with python3 for the Android?
Because the primary reason to use Kivy is to develop applications for Android.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From df at see.replyto.invalid  Fri Nov 13 11:35:56 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Fri, 13 Nov 2015 16:35:56 +0000
Subject: don't understand matrix-multiplication should be reversed in
 python?
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
 <mailman.280.1447365421.16136.python-list@python.org>
 <11344ffd-f594-4059-8c41-6bacbdb66f10@googlegroups.com>
Message-ID: <mj2c4b55qf6cfcbsh96465lmah3908hjpv@4ax.com>

PythonDude <mjoerg.phone at gmail.com> wrote:

>On Thursday, 12 November 2015 22:57:21 UTC+1, Robert Kern  wrote:

>> He simply instantiated the two vectors as row-vectors instead of column-vectors, 
>> which he could have easily done, so he had to flip the matrix expression.
>
>Thank you very much Robert - I just had to be sure about it :-)

Yep, he's evidently used to the Matlab/Octave way of defining "vectors"
which is somewhat easier for a math-oriented interactive environment.

It's just a *bit* more laborious to append columns in numpy.

>>> from numpy import *
>>> v1=vstack([0,1,2])
>>> v2=vstack([3,4,5])
>>> c_[v1,v2]
array([[0, 3],
       [1, 4],
       [2, 5]])
>>> append(v1,v2,axis=1)
array([[0, 3],
       [1, 4],
       [2, 5]])
>>> v3=mat('4;5;6')
>>> v4=mat('7;8;9')
>>> c_[v3,v4]
matrix([[4, 7],
        [5, 8],
        [6, 9]])


From ian.g.kelly at gmail.com  Fri Nov 13 12:16:49 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 10:16:49 -0700
Subject: numpy column_stack - why does this work?
In-Reply-To: <0b4725a8-a040-4bfb-b046-81c2e529447a@googlegroups.com>
References: <0b4725a8-a040-4bfb-b046-81c2e529447a@googlegroups.com>
Message-ID: <CALwzidnQiy-pEH-iVNA0g6-u3Us2M077QftTq1q8MbFHCiHtVg@mail.gmail.com>

On Fri, Nov 13, 2015 at 8:37 AM, PythonDude <mjoerg.phone at gmail.com> wrote:
> Hi all,
>
> Just a quick question about this code-piece (it works, I've tested it):
>
> means, stds = np.column_stack([
>     getMuSigma_from_PF(return_vec)
>     for _ in xrange(n_portfolios) ])
>
>
> 1) I understand column_stack does this (assembles vectors vertically, side-by-side):
>
>>>> a = np.array((1,2,3)) # NB: a is row-vector: {1 2 3}
>>>> b = np.array((2,3,4)) # NB: b is also a row-vector...
>>>> np.column_stack((a,b))
> array([[1, 2],
>        [2, 3],
>        [3, 4]])
>
> 2) I understand the underscore is just a "dummy variable" in the last line "for _ in xrange(n_portfolios)" - this also looked a bit confusing to me, at first...
>
> 3) I DON'T understand why the code doesn't look like this:
>
> means, stds = np.column_stack([
>     for _ in xrange(n_portfolios):
>       getMuSigma_from_PF(return_vec) ])

Because that would be invalid syntax; you can't put a for loop inside
an expression like that. Your question is not about numpy.column_stack
at all, but about list comprehensions. I suggest you start by reading
this:

https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions

Then if you're still confused, come back and ask further questions.


From torriem at gmail.com  Fri Nov 13 12:21:33 2015
From: torriem at gmail.com (Michael Torrie)
Date: Fri, 13 Nov 2015 10:21:33 -0700
Subject: Trying out Kivy
In-Reply-To: <871tbt3lml.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
Message-ID: <56461C1D.9060903@gmail.com>

On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
> I tried to install pygame and PIL with pip3, but that did not find
> anything. 

The replacement for PIL is called Pillow.  I'm not sure if it's a
drop-in replacement or not.  If it's not, then you'd have to modify Kivy
to import from Pillow.  Pillow does support Python3.

> Is there another way to install those dependencies?

Did you do a search to find out a) if PyGame supports Python3 (it does)
and b) where to go to download the source code for it? (their home page)?

PyPi is nice, but it's not the only place you can get useful Python
modules from.

> But more importantly: can I develop with python3 for the Android?
> Because the primary reason to use Kivy is to develop applications for Android.

Again, did you do a quick Google search?


From tjreedy at udel.edu  Fri Nov 13 12:23:45 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 13 Nov 2015 12:23:45 -0500
Subject: Trying out Kivy
In-Reply-To: <871tbt3lml.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
Message-ID: <n256b4$of5$1@ger.gmane.org>

On 11/13/2015 11:33 AM, Cecil Westerhof wrote:
> I tried out the ?standard? Kivy application:
> ============================================================
> from kivy.app import App
> from kivy.uix.button import Button
>
> class TestApp(App):
>      def build(self):
>          return Button(text='Hello World')
>
> TestApp().run()
> ============================================================
>
> When using python2 I see some exceptions and OSErrors, but it runs.
>
> When using python3 I get:
>      [CRITICAL          ] [Text        ] Unable to find any valuable Text provider at all!
>      pygame - ImportError: No module named 'pygame'
>        File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
>          fromlist=[modulename], level=0)
>        File "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pygame.py", line 12, in <module>
>          import pygame
>
>      pil - ImportError: No module named 'PIL'
>        File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
>          fromlist=[modulename], level=0)
>        File "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pil.py", line 8, in <module>
>          from PIL import Image, ImageFont, ImageDraw
>
>      [CRITICAL          ] [App         ] Unable to get a Text provider, abort.
>
> I tried to install pygame and PIL with pip3, but that did not find

Use pillow rather than PIL.  API is same.  Don't know about rest of your 
question.

> anything. Is there another way to install those dependencies?
>
> But more importantly: can I develop with python3 for the Android?
> Because the primary reason to use Kivy is to develop applications for Android.
>


-- 
Terry Jan Reedy




From abhishek.mallela at gmail.com  Fri Nov 13 12:44:04 2015
From: abhishek.mallela at gmail.com (Abhishek Mallela)
Date: Fri, 13 Nov 2015 11:44:04 -0600
Subject: Matplotlib error: Value Error: x and y must have same first
 dimension
In-Reply-To: <201511131543.tADFhsvL006539@fido.openend.se>
References: <40964e99-cd31-4daa-8f5f-069b09816b3d@googlegroups.com>
 <201511130834.tAD8YNra005833@fido.openend.se>
 <CAHVvXxQVs7O8K7cCiya7=yovwxHAdPoPZh6CQV4hsMEFroBYLA@mail.gmail.com>
 <201511131543.tADFhsvL006539@fido.openend.se>
Message-ID: <CAEQM-itEv44CG9LRfKzhKoXWJDY1xZ9rT9GbAXNzR4SRZBnh5w@mail.gmail.com>

Thank you Laura and Oscar.

Abhishek


From wabayang at gmail.com  Fri Nov 13 12:50:52 2015
From: wabayang at gmail.com (bayang)
Date: Fri, 13 Nov 2015 18:50:52 +0100
Subject: Trying out Kivy
In-Reply-To: <n256b4$of5$1@ger.gmane.org>
References: <871tbt3lml.fsf@Equus.decebal.nl> <n256b4$of5$1@ger.gmane.org>
Message-ID: <564622FC.4020208@gmail.com>

Le 13/11/2015 18:23, Terry Reedy a ?crit :
> On 11/13/2015 11:33 AM, Cecil Westerhof wrote:
>> I tried out the ?standard? Kivy application:
>> ============================================================
>> from kivy.app import App
>> from kivy.uix.button import Button
>>
>> class TestApp(App):
>>      def build(self):
>>          return Button(text='Hello World')
>>
>> TestApp().run()
>> ============================================================
>>
>> When using python2 I see some exceptions and OSErrors, but it runs.
>>
>> When using python3 I get:
>>      [CRITICAL          ] [Text        ] Unable to find any valuable 
>> Text provider at all!
>>      pygame - ImportError: No module named 'pygame'
>>        File 
>> "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, 
>> in core_select_lib
>>          fromlist=[modulename], level=0)
>>        File 
>> "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pygame.py", 
>> line 12, in <module>
>>          import pygame
>>
>>      pil - ImportError: No module named 'PIL'
>>        File 
>> "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, 
>> in core_select_lib
>>          fromlist=[modulename], level=0)
>>        File 
>> "/usr/lib64/python3.4/site-packages/kivy/core/text/text_pil.py", line 
>> 8, in <module>
>>          from PIL import Image, ImageFont, ImageDraw
>>
>>      [CRITICAL          ] [App         ] Unable to get a Text 
>> provider, abort.
>>
>> I tried to install pygame and PIL with pip3, but that did not find
>
> Use pillow rather than PIL.  API is same.  Don't know about rest of 
> your question.
>
>> anything. Is there another way to install those dependencies?
>>
>> But more importantly: can I develop with python3 for the Android?
>> Because the primary reason to use Kivy is to develop applications for 
>> Android.
>>
>
>
Got the same issue a few days ago with python3.
Installed pygame dependencies, installed pygame, installed pillow and 
everything went fine (using pip in virtualenv)



From Cecil at decebal.nl  Fri Nov 13 13:30:00 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Fri, 13 Nov 2015 19:30:00 +0100
Subject: Trying out Kivy
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
Message-ID: <87pozd21nb.fsf@Equus.decebal.nl>

On Friday 13 Nov 2015 18:21 CET, Michael Torrie wrote:

> On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
>> I tried to install pygame and PIL with pip3, but that did not find
>> anything. 
>
> The replacement for PIL is called Pillow. I'm not sure if it's a
> drop-in replacement or not. If it's not, then you'd have to modify
> Kivy to import from Pillow. Pillow does support Python3.

After installing Pillow the error about PIL disappeared, but I got new
errors about bcm and x11.


>> Is there another way to install those dependencies?
>
> Did you do a search to find out a) if PyGame supports Python3 (it
> does) and b) where to go to download the source code for it? (their
> home page)?
>
> PyPi is nice, but it's not the only place you can get useful Python
> modules from.
>
>> But more importantly: can I develop with python3 for the Android?
>> Because the primary reason to use Kivy is to develop applications
>> for Android.
>
> Again, did you do a quick Google search?

I did. But I did not find specifics about the version of Python.

Well, maybe I should first play a bit with Kivy and if it is the way
to go, I delve into the python3 bit.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From tundraBOGUS at tundraware.com  Fri Nov 13 14:14:08 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Fri, 13 Nov 2015 13:14:08 -0600
Subject: More tkinter Madness
In-Reply-To: <n2400v$h96$1@dont-email.me>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
Message-ID: <0dphhc-ntf.ln1@oceanview.tundraware.com>

On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
> Apfelkiste:Sources chris$

Well, I get window and when I do this:

pack [button .b -text Hello -command exit]

Nothing appears.

tkinter appears borked

I have reinstalled once already, will try again




From kent at z-sverige.nu  Fri Nov 13 14:20:45 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Fri, 13 Nov 2015 14:20:45 -0500
Subject: Problems using struct pack/unpack in files, and reading them.
Message-ID: <20151113192045.GA9913@z-sverige.nu>

Hi there,
Im deeply sorry for yet another question to this list.  I have come across a problem to which google seems not 
to eager to supply the anwser.

The problem is the following.
First I do this:

def setup_drive():
    test = pack('>HH',  0b1000000000000000, 0b1000000100000001)
    file = open('drive.bin', 'wb')
    for x in range(640000):
        file.write(test)
    file.close()


I have a pack, which I fill the file with. The data is not of interrest right now.

This all works great.
Then I do this:


def LoadCommandAndReact(place_to_read):
    global RegisterAX
    
    tmp = place_to_read.read()[RegisterAX:calcsize('HH')]
    klar = unpack('>HH', tmp)

    if place_to_read.closed:
       print("Drive error. Drive closed.")
    else:
       pass

    if checkfirstbit(klar[RegisterAX]):
       print("First bit is set. Move Cmd.")
       if (klar[0] & 0b0111111111111111):
          print("Cmd ERROR: Multiple commands is set.")
          pass
       else:
          #Here something to do with mv command.
          print("Adress to read to, from the offset of the command")
          print(klar[RegisterAX+1])  #Variable is always Offset+1          
    else:
       print("First bit is not set.")
    #Change RegisterAX offset+2bytes, 
    RegisterAX=+2   #We read two bytes per cycle. Becaus command is first, and variables are second.    




This all works If I run the LoadCommand..  only once.
But when I  run it for the second time,  it complains:

Traceback (most recent call last):
  File "core.py", line 98, in <module>
    LoadCommandAndReact(readfile)
  File "core.py", line 30, in LoadCommandAndReact
    klar = unpack('>HH', tmp)
struct.error: unpack requires a string argument of length 4



Im having trouble understanding the error.   unpack requires a string argument of length 4.
I have filled the file with data that should be readable, and is readable by the function 
when I run it for the first time. And since the file is filled with duplicates; should it not be readable the second
time aswell? I change the RegisterAX =+2. The amount I add should not matter, Its just my "offset" of where to read in the file.
The problem seems that the second time, unpack doesnt get the size of '>HH' to read. But surely 
.read()[RegisterAX:calcsize('HH')]  should assure that its fed with correct data?

I have filled the file with data of size '>HH' and first command reads that.  So next read should read the next
duplicate of that data that has been written to the file?


I understand its hard to read, and a long email. So well, its just a cry out in the dark evening.  If some one can
share some light.. I would be much happy about it.

/Kent.


From ian.g.kelly at gmail.com  Fri Nov 13 14:36:22 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 12:36:22 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113192045.GA9913@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
Message-ID: <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>

On Fri, Nov 13, 2015 at 12:20 PM, kent nyberg <kent at z-sverige.nu> wrote:
> def LoadCommandAndReact(place_to_read):
>     global RegisterAX
>
>     tmp = place_to_read.read()[RegisterAX:calcsize('HH')]

It looks like you're trying to get a slice of length 4 here, starting
at the value of RegisterAX. What you're actually getting is a slice
starting at the value of RegisterAX and ending at 4. You probably want
this instead:

    tmp = place_to_read.read()[RegisterAX:RegisterAX + calcsize('HH')]


From ian.g.kelly at gmail.com  Fri Nov 13 14:45:42 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 12:45:42 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113192045.GA9913@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
Message-ID: <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>

As long as I'm replying to this, I see a few more issues to comment on:

On Fri, Nov 13, 2015 at 12:20 PM, kent nyberg <kent at z-sverige.nu> wrote:
>     if place_to_read.closed:
>        print("Drive error. Drive closed.")

You probably also want to break or return here. Even better: raise an
exception instead of printing.

That said, why would this ever be closed here, since you just read
from it two lines prior (which would have raised an exception if the
file were closed), and you haven't closed it in the meantime?

>     if checkfirstbit(klar[RegisterAX]):
>        print("First bit is set. Move Cmd.")
>        if (klar[0] & 0b0111111111111111):
>           print("Cmd ERROR: Multiple commands is set.")

Why do you pass the commands in a bit field if you're not going to
allow multiple commands to be set? Also, see above about
break/return/exception.

>           pass

Unnecessary.

>     #Change RegisterAX offset+2bytes,
>     RegisterAX=+2   #We read two bytes per cycle. Becaus command is first, and variables are second.

This sets RegisterAX to 2. Specifically, positive 2. If you want to
*add* 2, you probably meant to write:

    RegisterAX += 2

This also points out a good reason for using spaces around operators,
as "RegisterAX =+ 2" would have caused a SyntaxError and been more
easily detectable.


From torriem at gmail.com  Fri Nov 13 14:53:50 2015
From: torriem at gmail.com (Michael Torrie)
Date: Fri, 13 Nov 2015 12:53:50 -0700
Subject: Trying out Kivy
In-Reply-To: <87pozd21nb.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
Message-ID: <56463FCE.3030107@gmail.com>

On 11/13/2015 11:30 AM, Cecil Westerhof wrote:
> On Friday 13 Nov 2015 18:21 CET, Michael Torrie wrote:
> 
>> On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
>>> I tried to install pygame and PIL with pip3, but that did not find
>>> anything. 
>>
>> The replacement for PIL is called Pillow. I'm not sure if it's a
>> drop-in replacement or not. If it's not, then you'd have to modify
>> Kivy to import from Pillow. Pillow does support Python3.
> 
> After installing Pillow the error about PIL disappeared, but I got new
> errors about bcm and x11.

Traceback?



From lac at openend.se  Fri Nov 13 14:56:00 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 20:56:00 +0100
Subject: More tkinter Madness
In-Reply-To: <0dphhc-ntf.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com>
Message-ID: <201511131956.tADJu0fb026608@fido.openend.se>

In a message of Fri, 13 Nov 2015 13:14:08 -0600, Tim Daneliuk writes:
>On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>> Apfelkiste:Sources chris$
>
>Well, I get window and when I do this:
>
>pack [button .b -text Hello -command exit]
>
>Nothing appears.
>
>tkinter appears borked
>
>I have reinstalled once already, will try again

Next idea.

Try to run a basic Tk app and a basic Tcl one.  See if they work or not.

Laura



From torriem at gmail.com  Fri Nov 13 14:58:00 2015
From: torriem at gmail.com (Michael Torrie)
Date: Fri, 13 Nov 2015 12:58:00 -0700
Subject: More tkinter Madness
In-Reply-To: <0dphhc-ntf.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com>
Message-ID: <564640C8.1090608@gmail.com>

On 11/13/2015 12:14 PM, Tim Daneliuk wrote:
> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>> Apfelkiste:Sources chris$
> 
> Well, I get window and when I do this:
> 
> pack [button .b -text Hello -command exit]
> 
> Nothing appears.
> 
> tkinter appears borked
> 
> I have reinstalled once already, will try again

Tkinter is the name of the Python package for using Tk, but Tk itself is
usually called Tk (package on Fedora and RHEL is tk).

On my CentOS installs, in /usr/share/tk8.5/demos, there are a number of
Tcl/Tk demos you can run.  If Tcl and Tk are working, then I would move
to reinstalling tkinter.



From Cecil at decebal.nl  Fri Nov 13 15:10:55 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Fri, 13 Nov 2015 21:10:55 +0100
Subject: Trying out Kivy
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
 <mailman.300.1447444435.16136.python-list@python.org>
Message-ID: <87lha11wz4.fsf@Equus.decebal.nl>

On Friday 13 Nov 2015 20:53 CET, Michael Torrie wrote:

> On 11/13/2015 11:30 AM, Cecil Westerhof wrote:
>> On Friday 13 Nov 2015 18:21 CET, Michael Torrie wrote:
>>
>>> On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
>>>> I tried to install pygame and PIL with pip3, but that did not
>>>> find anything.
>>>
>>> The replacement for PIL is called Pillow. I'm not sure if it's a
>>> drop-in replacement or not. If it's not, then you'd have to modify
>>> Kivy to import from Pillow. Pillow does support Python3.
>>
>> After installing Pillow the error about PIL disappeared, but I got
>> new errors about bcm and x11.
>
> Traceback?

Purge log fired. Analysing...
Purge finished!
[INFO              ] [Logger      ] Record log in /home/cecil/.kivy/logs/kivy_15-11-13_28.txt
[INFO              ] [Kivy        ] v1.9.0
[INFO              ] [Python      ] v3.4.1 (default, May 23 2014, 17:48:28) [GCC]
[INFO              ] [Factory     ] 173 symbols loaded
[INFO              ] [Image       ] Providers: img_tex, img_dds, img_gif, img_pil (img_pygame, img_ffpyplayer ignored)
[INFO              ] [Text        ] Provider: pil(['text_pygame'] ignored)
[CRITICAL          ] [Window      ] Unable to find any valuable Window provider at all!
egl_rpi - ImportError: cannot import name 'bcm'
  File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
    fromlist=[modulename], level=0)
  File "/usr/lib64/python3.4/site-packages/kivy/core/window/window_egl_rpi.py", line 12, in <module>
    from kivy.lib.vidcore_lite import bcm, egl

pygame - ImportError: No module named 'pygame'
  File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
    fromlist=[modulename], level=0)
  File "/usr/lib64/python3.4/site-packages/kivy/core/window/window_pygame.py", line 8, in <module>
    import pygame

x11 - ImportError: No module named 'kivy.core.window.window_x11'
  File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
    fromlist=[modulename], level=0)

[CRITICAL          ] [App         ] Unable to get a Window, abort.
 Exception ignored in: 'kivy.properties.dpi2px'
 Traceback (most recent call last):
   File "/usr/lib64/python3.4/site-packages/kivy/utils.py", line 360, in __get__
     retval = self.func(inst)
   File "/usr/lib64/python3.4/site-packages/kivy/metrics.py", line 169, in dpi
     EventLoop.ensure_window()
   File "/usr/lib64/python3.4/site-packages/kivy/base.py", line 126, in ensure_window
     sys.exit(1)
 SystemExit: 1
[CRITICAL          ] [App         ] Unable to get a Window, abort.


I see a difference with python2. (Did not notice it before.) With
python3 v1.9.0 is installed, but with python2 v1.8.0.
    [INFO              ] Kivy v1.8.0

Maybe that is the problem?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From kent at z-sverige.nu  Fri Nov 13 15:15:10 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Fri, 13 Nov 2015 15:15:10 -0500
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
Message-ID: <20151113201510.GA10107@z-sverige.nu>

On Fri, Nov 13, 2015 at 12:36:22PM -0700, Ian Kelly wrote:
> On Fri, Nov 13, 2015 at 12:20 PM, kent nyberg <kent at z-sverige.nu> wrote:
> > def LoadCommandAndReact(place_to_read):
> >     global RegisterAX
> >
> >     tmp = place_to_read.read()[RegisterAX:calcsize('HH')]
> 
> It looks like you're trying to get a slice of length 4 here, starting
> at the value of RegisterAX. What you're actually getting is a slice
> starting at the value of RegisterAX and ending at 4. You probably want
> this instead:
> 
>     tmp = place_to_read.read()[RegisterAX:RegisterAX + calcsize('HH')]
> -- 
> https://mail.python.org/mailman/listinfo/python-list


Even with that, it still gets wrong.
I also tried .read()[RegisterAX:RegisterAX+4]

As for the other suggestions you had in the second reply, I can comment on them later.
 For now though, I just want to be able to loop this specific function.

I do appriciate that you took the time. :)

What bothers me, is the error that says 
unpack requires a string argument of 4 bytes.
Im thinking in the line of arguments? Does unpack look at the 4 bytes it has read, and tell for some 
reason say that unpacking needs an argument of 4 bytes?  I know that I can set the arguments 
for unpack. I have done that.  It is: unpack('>HH', tmp).
So either '>HH' or tmp is wrong. Since '>HH' worked for the first run of the function, I assume its correct.
And as far as I know,   doing .read()[RegisterAX:RegisterAX:+4]  should read the following
4 bytes.

I have even tried doing .read(4),  since then python should manage where to start and  read 4?

Still it complains?


From lac at openend.se  Fri Nov 13 15:15:23 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 21:15:23 +0100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113192045.GA9913@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
Message-ID: <201511132015.tADKFNA5028148@fido.openend.se>

In a message of Fri, 13 Nov 2015 14:20:45 -0500, kent nyberg writes:
>Hi there,
>Im deeply sorry for yet another question to this list.  I have come across a problem to which google seems not 
>to eager to supply the anwser.
>
>The problem is the following.
>First I do this:
>
>def setup_drive():
>    test = pack('>HH',  0b1000000000000000, 0b1000000100000001)
>    file = open('drive.bin', 'wb')
>    for x in range(640000):
>        file.write(test)
>    file.close()
>
>
>I have a pack, which I fill the file with. The data is not of interrest right now.
>
>This all works great.
>Then I do this:
>
>
>def LoadCommandAndReact(place_to_read):
>    global RegisterAX
>    
>    tmp = place_to_read.read()[RegisterAX:calcsize('HH')]
>    klar = unpack('>HH', tmp)
>
>    if place_to_read.closed:
>       print("Drive error. Drive closed.")
>    else:
>       pass
>
>    if checkfirstbit(klar[RegisterAX]):
>       print("First bit is set. Move Cmd.")
>       if (klar[0] & 0b0111111111111111):
>          print("Cmd ERROR: Multiple commands is set.")
>          pass
>       else:
>          #Here something to do with mv command.
>          print("Adress to read to, from the offset of the command")
>          print(klar[RegisterAX+1])  #Variable is always Offset+1          
>    else:
>       print("First bit is not set.")
>    #Change RegisterAX offset+2bytes, 
>    RegisterAX=+2   #We read two bytes per cycle. Becaus command is first, and variables are second.    
>
>
>
>
>This all works If I run the LoadCommand..  only once.
>But when I  run it for the second time,  it complains:
>
>Traceback (most recent call last):
>  File "core.py", line 98, in <module>
>    LoadCommandAndReact(readfile)
>  File "core.py", line 30, in LoadCommandAndReact
>    klar = unpack('>HH', tmp)
>struct.error: unpack requires a string argument of length 4
>
>
>
>Im having trouble understanding the error.   unpack requires a string argument of length 4.
>I have filled the file with data that should be readable, and is readable by the function 
>when I run it for the first time. And since the file is filled with duplicates; should it not be readable the second
>time aswell? I change the RegisterAX =+2. The amount I add should not matter, Its just my "offset" of where to read in the file.
>The problem seems that the second time, unpack doesnt get the size of '>HH' to read. But surely 
>.read()[RegisterAX:calcsize('HH')]  should assure that its fed with correct data?
>
>I have filled the file with data of size '>HH' and first command reads that.  So next read should read the next
>duplicate of that data that has been written to the file?
>
>
>I understand its hard to read, and a long email. So well, its just a cry out in the dark evening.  If some one can
>share some light.. I would be much happy about it.
>
>/Kent.
>-- 
>https://mail.python.org/mailman/listinfo/python-list

struct wants to know exactly how many of those things you have.
You only told it about one of them .... i.e.  If you want to unpack 999 
elements from binary data

data = struct.unpack("999H", B)

Laura




From lac at openend.se  Fri Nov 13 15:17:31 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 13 Nov 2015 21:17:31 +0100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113192045.GA9913@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
Message-ID: <201511132017.tADKHVw6028340@fido.openend.se>

I forgot to add.  You get this wretched error message if your data
is shorter than expected, and you ask struct to read more than you
have, as well.  most annoying.

Laura


From ian.g.kelly at gmail.com  Fri Nov 13 16:00:36 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 14:00:36 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113201510.GA10107@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
 <20151113201510.GA10107@z-sverige.nu>
Message-ID: <CALwzidkMYnnsg1pe6MkBAeh=Tu-nWErk+NLQ82a6XS0q__bP=Q@mail.gmail.com>

On Fri, Nov 13, 2015 at 1:15 PM, kent nyberg <kent at z-sverige.nu> wrote:
> Even with that, it still gets wrong.
> I also tried .read()[RegisterAX:RegisterAX+4]

When you call read for the second time, are you just reading the same
file again without closing or seeking it in the interim? If that's the
case, then you would get an empty string the second time, which would
explain your error.

Either retain the read data between calls, or call seek(0) before
reading it again.


From ian.g.kelly at gmail.com  Fri Nov 13 16:05:04 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 14:05:04 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <20151113201510.GA10107@z-sverige.nu>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
 <20151113201510.GA10107@z-sverige.nu>
Message-ID: <CALwzid=kcW=exEiVEYMeYrX_C2edzarhVRfzc7YHUNAy_KR+qg@mail.gmail.com>

On Fri, Nov 13, 2015 at 1:15 PM, kent nyberg <kent at z-sverige.nu> wrote:
> What bothers me, is the error that says
> unpack requires a string argument of 4 bytes.
> Im thinking in the line of arguments? Does unpack look at the 4 bytes it has read, and tell for some
> reason say that unpacking needs an argument of 4 bytes?  I know that I can set the arguments
> for unpack. I have done that.  It is: unpack('>HH', tmp).
> So either '>HH' or tmp is wrong. Since '>HH' worked for the first run of the function, I assume its correct.
> And as far as I know,   doing .read()[RegisterAX:RegisterAX:+4]  should read the following
> 4 bytes.

By the way, I would strongly suggest that you print or log the value
of repr(tmp) so that you *know* what you're passing to unpack rather
than having to speculate about it.


From wabayang at gmail.com  Fri Nov 13 16:11:35 2015
From: wabayang at gmail.com (bayang)
Date: Fri, 13 Nov 2015 22:11:35 +0100
Subject: Trying out Kivy
In-Reply-To: <87lha11wz4.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
 <mailman.300.1447444435.16136.python-list@python.org>
 <87lha11wz4.fsf@Equus.decebal.nl>
Message-ID: <56465207.1030002@gmail.com>

Le 13/11/2015 21:10, Cecil Westerhof a ?crit :
> Purge log fired. Analysing...
> Purge finished!
> [INFO              ] [Logger      ] Record log in /home/cecil/.kivy/logs/kivy_15-11-13_28.txt
> [INFO              ] [Kivy        ] v1.9.0
> [INFO              ] [Python      ] v3.4.1 (default, May 23 2014, 17:48:28) [GCC]
> [INFO              ] [Factory     ] 173 symbols loaded
> [INFO              ] [Image       ] Providers: img_tex, img_dds, img_gif, img_pil (img_pygame, img_ffpyplayer ignored)
> [INFO              ] [Text        ] Provider: pil(['text_pygame'] ignored)
> [CRITICAL          ] [Window      ] Unable to find any valuable Window provider at all!
> egl_rpi - ImportError: cannot import name 'bcm'
>    File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
>      fromlist=[modulename], level=0)
>    File "/usr/lib64/python3.4/site-packages/kivy/core/window/window_egl_rpi.py", line 12, in <module>
>      from kivy.lib.vidcore_lite import bcm, egl
>
> pygame - ImportError: No module named 'pygame'
>    File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
>      fromlist=[modulename], level=0)
>    File "/usr/lib64/python3.4/site-packages/kivy/core/window/window_pygame.py", line 8, in <module>
>      import pygame
>
> x11 - ImportError: No module named 'kivy.core.window.window_x11'
>    File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57, in core_select_lib
>      fromlist=[modulename], level=0)
>
> [CRITICAL          ] [App         ] Unable to get a Window, abort.
>   Exception ignored in: 'kivy.properties.dpi2px'
>   Traceback (most recent call last):
>     File "/usr/lib64/python3.4/site-packages/kivy/utils.py", line 360, in __get__
>       retval = self.func(inst)
>     File "/usr/lib64/python3.4/site-packages/kivy/metrics.py", line 169, in dpi
>       EventLoop.ensure_window()
>     File "/usr/lib64/python3.4/site-packages/kivy/base.py", line 126, in ensure_window
>       sys.exit(1)
>   SystemExit: 1
> [CRITICAL          ] [App         ] Unable to get a Window, abort.
>
>
> I see a difference with python2. (Did not notice it before.) With
> python3 v1.9.0 is installed, but with python2 v1.8.0.
>      [INFO              ] Kivy v1.8.0
>
> Maybe that is the problem?
>
Pygame doesn't seem to be correctly installed.
check this : http://www.pygame.org/wiki/CompileUbuntu#Python_3.x
in "installing pygame with pip" part.
Install dependencies first, then
pip install hg+http://bitbucket.org/pygame/pygame



From invalid at invalid.invalid  Fri Nov 13 16:17:59 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 13 Nov 2015 21:17:59 +0000 (UTC)
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
 <20151113201510.GA10107@z-sverige.nu>
 <mailman.306.1447448484.16136.python-list@python.org>
Message-ID: <n25k27$m37$1@reader1.panix.com>

On 2015-11-13, Ian Kelly <ian.g.kelly at gmail.com> wrote:

> Either retain the read data between calls, or call seek(0) before
> reading it again.

It has always saddened me that Python files don't have a rewind()
method.  On Unix, calling rewind() is the same as calling seek(0), so
it's utterly pointless except as an amusing anachronistic name: it
always made me smile when called rewind() on a file in a filesystem on
a hard-drive.  Interestingly, you can't you can't (and never could)
use rewind() to rewind a tape. You use an ioctl() system call for
that.

-- 
Grant Edwards               grant.b.edwards        Yow! HUGH BEAUMONT died
                                  at               in 1982!!
                              gmail.com            


From auriocus at gmx.de  Fri Nov 13 16:30:47 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Fri, 13 Nov 2015 22:30:47 +0100
Subject: More tkinter Madness
In-Reply-To: <0dphhc-ntf.ln1@oceanview.tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com>
Message-ID: <n25klu$rij$1@dont-email.me>

Am 13.11.15 um 20:14 schrieb Tim Daneliuk:
> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>> Apfelkiste:Sources chris$
>
> Well, I get window and when I do this:
>
> pack [button .b -text Hello -command exit]
>
> Nothing appears.

No error, nothing? Just to be sure, you haven't closed the empty window, 
that appeared when you typed "wish"? and copied the command into the 
wish prompt?

> tkinter appears borked
> I have reinstalled once already, will try again

This is using pure Tcl/Tk. If it is not working, reinstall the 
corresponding packages in your distro. tkinter is merely the Python 
interface to those.

	Christian


From kent at z-sverige.nu  Fri Nov 13 16:34:50 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Fri, 13 Nov 2015 16:34:50 -0500
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <n25k27$m37$1@reader1.panix.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
 <20151113201510.GA10107@z-sverige.nu>
 <mailman.306.1447448484.16136.python-list@python.org>
 <n25k27$m37$1@reader1.panix.com>
Message-ID: <20151113213450.GA11001@z-sverige.nu>

The main problem was that I forgot to do seek(0).  Thanks alot people.

Though, as many times before, the problem was due to misunderstanding of how python works.
I assumed file.read()[xx:yy] was to be understood as,   in the file, read from index xx to place yy.
That is,  [10:20]  was the same as,   read from 10th char to 20th.  Sort of.


Is it true then to say that every .read  of a file, places an index-offset (?) from where the next read starts?
That is, I need to rewind the file, or else the read will start from where the last read stopped?


From invalid at invalid.invalid  Fri Nov 13 16:44:49 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 13 Nov 2015 21:44:49 +0000 (UTC)
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com>
 <20151113201510.GA10107@z-sverige.nu>
 <mailman.306.1447448484.16136.python-list@python.org>
 <n25k27$m37$1@reader1.panix.com>
 <mailman.309.1447450493.16136.python-list@python.org>
Message-ID: <n25lkh$egl$1@reader1.panix.com>

On 2015-11-13, kent nyberg <kent at z-sverige.nu> wrote:

> Though, as many times before, the problem was due to misunderstanding
> of how python works. I assumed file.read()[xx:yy] was to be
> understood as, in the file, read from index xx to place yy.

Nope.

   First, the 'file.read()' part is evaluated.  That returns the
   entire contents of the file.

   Next, the '[xx:yy]' slice operation is done on the entire contents
   returned in the first step.  The slice operation retuns bytes xx
   through yy-1 (inclusive), and discards the rest of the data.

> Is it true then to say that every .read of a file, places an
> index-offset (?) from where the next read starts?

Yes.  a file object has a current index.  A read() operation always
starts at that index.  When you open the file, that index is 0.  Each
time you read from the file, the index is advanced past the data that
was read.  The seek() method sets that index to whatever you want.

> That is, I need to rewind the file, or else the read will start from
> where the last read stopped?

Exactly.

-- 
Grant Edwards               grant.b.edwards        Yow! Mr and Mrs PED, can I
                                  at               borrow 26.7% of the RAYON
                              gmail.com            TEXTILE production of the
                                                   INDONESIAN archipelago?


From tundraBOGUS at tundraware.com  Fri Nov 13 17:09:46 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Fri, 13 Nov 2015 16:09:46 -0600
Subject: More tkinter Madness
In-Reply-To: <mailman.302.1447444684.16136.python-list@python.org>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com>
 <mailman.302.1447444684.16136.python-list@python.org>
Message-ID: <56465FAA.5060809@tundraware.com>

On 11/13/2015 01:58 PM, Michael Torrie wrote:
> On 11/13/2015 12:14 PM, Tim Daneliuk wrote:
>> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>>> Apfelkiste:Sources chris$
>>
>> Well, I get window and when I do this:
>>
>> pack [button .b -text Hello -command exit]
>>
>> Nothing appears.
>>
>> tkinter appears borked
>>
>> I have reinstalled once already, will try again
> 
> Tkinter is the name of the Python package for using Tk, but Tk itself is
> usually called Tk (package on Fedora and RHEL is tk).
> 
> On my CentOS installs, in /usr/share/tk8.5/demos, there are a number of
> Tcl/Tk demos you can run.  If Tcl and Tk are working, then I would move
> to reinstalling tkinter.
> 

Yep, tcl/tk is borked.  That would explain why pure X apps like xterm work, but not tkinter apps.
Reinstalling tcl/tk has not helped at all.  Now I am really curious what the interaction is between VPS and tk... Sigh. 


(Thanks)



From tundraBOGUS at tundraware.com  Fri Nov 13 17:10:08 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Fri, 13 Nov 2015 16:10:08 -0600
Subject: More tkinter Madness
In-Reply-To: <mailman.301.1447444567.16136.python-list@python.org>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com>
 <mailman.301.1447444567.16136.python-list@python.org>
Message-ID: <56465FC0.9040608@tundraware.com>

On 11/13/2015 01:56 PM, Laura Creighton wrote:
> In a message of Fri, 13 Nov 2015 13:14:08 -0600, Tim Daneliuk writes:
>> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>>> Apfelkiste:Sources chris$
>>
>> Well, I get window and when I do this:
>>
>> pack [button .b -text Hello -command exit]
>>
>> Nothing appears.
>>
>> tkinter appears borked
>>
>> I have reinstalled once already, will try again
> 
> Next idea.
> 
> Try to run a basic Tk app and a basic Tcl one.  See if they work or not.
> 
> Laura
> 

Looks like tcl/tk is hosed for some reason.


From tundraBOGUS at tundraware.com  Fri Nov 13 17:10:42 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Fri, 13 Nov 2015 16:10:42 -0600
Subject: More tkinter Madness
In-Reply-To: <n25klu$rij$1@dont-email.me>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com> <n25klu$rij$1@dont-email.me>
Message-ID: <56465FE2.40701@tundraware.com>

On 11/13/2015 03:30 PM, Christian Gollwitzer wrote:
> Am 13.11.15 um 20:14 schrieb Tim Daneliuk:
>> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>>> Apfelkiste:Sources chris$
>>
>> Well, I get window and when I do this:
>>
>> pack [button .b -text Hello -command exit]
>>
>> Nothing appears.
> 
> No error, nothing? Just to be sure, you haven't closed the empty window, that appeared when you typed "wish"? and copied the command into the wish prompt?
> 
>> tkinter appears borked
>> I have reinstalled once already, will try again
> 
> This is using pure Tcl/Tk. If it is not working, reinstall the corresponding packages in your distro. tkinter is merely the Python interface to those.
> 
>     Christian

Yep tcl/tk is the culprit, but reinstalling has not helped.


From rosuav at gmail.com  Fri Nov 13 17:42:10 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 09:42:10 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
Message-ID: <CAPTjJmr3bf84ysE7ObfjHxTzW2pQQnvcsgovAY4SWAGuC7+REg@mail.gmail.com>

On Sat, Nov 14, 2015 at 6:45 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> This sets RegisterAX to 2. Specifically, positive 2. If you want to
> *add* 2, you probably meant to write:
>
>     RegisterAX += 2
>
> This also points out a good reason for using spaces around operators,
> as "RegisterAX =+ 2" would have caused a SyntaxError and been more
> easily detectable.

Err, no. Even with spaces, it works just fine, because unary plus is
allowed to be separated from its operand with spaces:

>>> x=1
>>> x =+ 2
>>> x = + 3
>>> x
3

However, this is a reasonable call for the abolition of unary plus...

ChrisA


From rxjwg98 at gmail.com  Fri Nov 13 18:04:20 2015
From: rxjwg98 at gmail.com (fl)
Date: Fri, 13 Nov 2015 15:04:20 -0800 (PST)
Subject: What is '@' for
Message-ID: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>

Hi,

I read the following code snippet. A question is here about '@'.
I don't find the answer online yet.

What function is it here?

BTW, below is for printing out?
    """theta = logit^{-1}(a+b)"""

but I don't see it is printed when the following could have been called.

Are you sure it would be printed out?


Thanks,





.................
import pymc
import numpy as np

n = 5*np.ones(4,dtype=int)
x = np.array([-.86,-.3,-.05,.73])
alpha = pymc.Normal('alpha',mu=0,tau=.01)
beta = pymc.Normal('beta',mu=0,tau=.01)

@pymc.deterministic
def theta(a=alpha, b=beta):
    """theta = logit^{-1}(a+b)"""
    return pymc.invlogit(a+b*x)
    
d = pymc.Binomial('d', n=n, p=theta, value=np.array([0.,1.,3.,5.]),\
    observed=True)


From rosuav at gmail.com  Fri Nov 13 18:14:11 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 10:14:11 +1100
Subject: What is '@' for
In-Reply-To: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
References: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
Message-ID: <CAPTjJmpczR8XLz7Fi+D-H03g2GELcTZtypO=BZvOiJsz0=zgLQ@mail.gmail.com>

On Sat, Nov 14, 2015 at 10:04 AM, fl <rxjwg98 at gmail.com> wrote:
> I read the following code snippet. A question is here about '@'.
> I don't find the answer online yet.
>
> What function is it here?
>
>
> @pymc.deterministic
> def theta(a=alpha, b=beta):
>     """theta = logit^{-1}(a+b)"""
>     return pymc.invlogit(a+b*x)

That's called a "function decorator". And now that you know the name,
you'll be able to find what it is online; as well as the Python docs,
there are a number of blog posts and other articles about it.

ChrisA


From tundraBOGUS at tundraware.com  Fri Nov 13 18:43:15 2015
From: tundraBOGUS at tundraware.com (Tim Daneliuk)
Date: Fri, 13 Nov 2015 17:43:15 -0600
Subject: What is '@' for
In-Reply-To: <mailman.311.1447456460.16136.python-list@python.org>
References: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
 <mailman.311.1447456460.16136.python-list@python.org>
Message-ID: <56467593.9060304@tundraware.com>

On 11/13/2015 05:14 PM, Chris Angelico wrote:
> On Sat, Nov 14, 2015 at 10:04 AM, fl <rxjwg98 at gmail.com> wrote:
>> I read the following code snippet. A question is here about '@'.
>> I don't find the answer online yet.
>>
>> What function is it here?
>>
>>
>> @pymc.deterministic
>> def theta(a=alpha, b=beta):
>>     """theta = logit^{-1}(a+b)"""
>>     return pymc.invlogit(a+b*x)
> 
> That's called a "function decorator". And now that you know the name,
> you'll be able to find what it is online; as well as the Python docs,
> there are a number of blog posts and other articles about it.
> 
> ChrisA
> 


One small point of order ... if you want to be precise, "@pymc.deterministic" is a *function decoration*.  The "decorator" is the function pymc.deterministic().

I know this is a fussy point, but this distinction is helpful when first learning the concept.


From tjreedy at udel.edu  Fri Nov 13 18:43:28 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 13 Nov 2015 18:43:28 -0500
Subject: What is '@' for
In-Reply-To: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
References: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
Message-ID: <n25sj3$ab1$1@ger.gmane.org>

On 11/13/2015 6:04 PM, fl wrote:

> I read the following code snippet. A question is here about '@'.
> I don't find the answer online yet.

Start with the index of the fine docs, which includes symbols.
https://docs.python.org/3/genindex-Symbols.html
'@' is near the end of the page.

> @pymc.deterministic
> def theta(a=alpha, b=beta):


-- 
Terry Jan Reedy



From greg.ewing at canterbury.ac.nz  Fri Nov 13 19:12:24 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Sat, 14 Nov 2015 13:12:24 +1300
Subject: don't understand matrix-multiplication should be reversed in
 python?
In-Reply-To: <mj2c4b55qf6cfcbsh96465lmah3908hjpv@4ax.com>
References: <ecc7eec6-3298-4f80-9bfb-eeecd3eeeb3a@googlegroups.com>
 <mailman.280.1447365421.16136.python-list@python.org>
 <11344ffd-f594-4059-8c41-6bacbdb66f10@googlegroups.com>
 <mj2c4b55qf6cfcbsh96465lmah3908hjpv@4ax.com>
Message-ID: <dancjaFn10oU1@mid.individual.net>

Dave Farrance wrote:
> Yep, he's evidently used to the Matlab/Octave way of defining "vectors"
> which is somewhat easier for a math-oriented interactive environment.
> 
> It's just a *bit* more laborious to append columns in numpy.

Yes, that's probably the main reason to do things that way.
A collection of vectors is most conveniently represented as
a 2D array where the first index selects one of the vectors.
But then to apply a transformation matrix to all the vectors,
you need to transpose the matrix and multiply it on the
right.

-- 
Greg


From vjp2.at at at.BioStrategist.dot.dot.com  Fri Nov 13 20:35:05 2015
From: vjp2.at at at.BioStrategist.dot.dot.com (vjp2.at at at.BioStrategist.dot.dot.com)
Date: Sat, 14 Nov 2015 01:35:05 +0000 (UTC)
Subject: Jython standalone
Message-ID: <n26349$hin$3@reader1.panix.com>

I click jython.org standalone jar and it just does a wait cycle.

What does it need to give me a prompt?


				    - = -
 Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
		    http://www.panix.com/~vjp2/vasos.htm
  ---{Nothing herein constitutes advice.  Everything fully disclaimed.}---
   [Homeland Security means private firearms not lazy obstructive guards]
 [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]


From orgnut at yahoo.com  Fri Nov 13 21:30:33 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Fri, 13 Nov 2015 18:30:33 -0800
Subject: Question about math.pi is mutable
In-Reply-To: <n249v4$f8n$1@dont-email.me>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me> <1590467.kktH0DaBsW@PointedEars.de>
 <n1lvpv$he1$1@dont-email.me> <85pozlidwu.fsf@benfinney.id.au>
 <mailman.112.1446940364.16136.python-list@python.org>
 <10882952.phYABH7ckh@PointedEars.de>
 <56450d07$0$1584$c3e8da3$5496439d@news.astraweb.com>
 <n249v4$f8n$1@dont-email.me>
Message-ID: <fvmdnSEu8uxRAdvLnZ2dnUU7-Q-dnZ2d@giganews.com>

On 11/13/2015 01:19 AM, Denis McMahon wrote:
> On Fri, 13 Nov 2015 09:04:54 +1100, Steven D'Aprano wrote:
>
>> On Fri, 13 Nov 2015 07:40 am, Thomas 'PointedEars' Lahn wrote:
>
>>> [crap I expect]
>
>> And you should consider the irony, and hypocrisy, of somebody who signs
>> his posts "PointedEars" bitching about supposed "real names".
>
> TPEL has been trolling html, php and javascript newsgroups for years,
> recently he seems to have discovered python newsgroups. :(
>
I found that TPEL post to be particularly amusing/ironic (hilarious, really) when he continued 
by talking about a group that ignores posts by people who don't use real names!   :-)
I generally ignore his posts as well.

      -=- Larry -=-     <-- My real name, which is NOT Lawrence (or anything similar)!



From steve at pearwood.info  Fri Nov 13 21:35:26 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 14 Nov 2015 13:35:26 +1100
Subject: Jython standalone
References: <n26349$hin$3@reader1.panix.com>
Message-ID: <56469dee$0$1612$c3e8da3$5496439d@news.astraweb.com>

On Sat, 14 Nov 2015 12:35 pm, vjp2.at at at.BioStrategist.dot.dot.com wrote:

> I click jython.org standalone jar and it just does a wait cycle.

I'm afraid I can't completely understand the problem you are having, since
you haven't really described it with sufficient detail. But my *guess* (and
this really is just a wild guess) is that you have clicked on a program
icon, and then nothing happens, so you think it is waiting. In most
operating systems, you need to *double-click*, not just click, to run the
program. Try double-clicking instead of single-clicking, and see if that
solves your problem.

If this is not your problem, please try explaining your problem. Help us to
help you, by giving us more information about your situation. Otherwise
we're just guessing.

What is "jython.org standalone jar", and where did it come from? Is this
code you wrote yourself, or code you downloaded? Where did you download it
from?

What is it supposed to do? What does it actually do?

What's a "wait cycle"? How long does it wait, and then what happens?

What operating system are you using? Windows, OS X, Linux, something else?
Version number?

Do you have Java installed? Are .jar files associated with the correct Java
executable?

 
> What does it need to give me a prompt?

What sort of prompt to you expect? A Python prompt, DOS prompt, something
else?



-- 
Steven



From steve at pearwood.info  Fri Nov 13 21:40:19 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 14 Nov 2015 13:40:19 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
Message-ID: <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>

On Sat, 14 Nov 2015 09:42 am, Chris Angelico wrote:

> However, this is a reasonable call for the abolition of unary plus...

The only way you'll take unary plus out of Python is by prying it from my
cold, dead hands.


BTW, unary minus suffers from the same "problem":

x =- y  # oops, meant x -= y

If anything, this is an argument against the augmented assignment
short-cuts, rather than the operators.


-- 
Steven



From rosuav at gmail.com  Fri Nov 13 22:01:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 14:01:41 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>

On Sat, Nov 14, 2015 at 1:40 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Sat, 14 Nov 2015 09:42 am, Chris Angelico wrote:
>
>> However, this is a reasonable call for the abolition of unary plus...
>
> The only way you'll take unary plus out of Python is by prying it from my
> cold, dead hands.
>
>
> BTW, unary minus suffers from the same "problem":
>
> x =- y  # oops, meant x -= y
>
> If anything, this is an argument against the augmented assignment
> short-cuts, rather than the operators.

Yes, unary minus has the same issue - but it's a lot more important
than unary plus is. In ECMAScript, unary plus means "force this to be
a number"; what's its purpose in Python?

ChrisA


From torriem at gmail.com  Fri Nov 13 22:11:47 2015
From: torriem at gmail.com (Michael Torrie)
Date: Fri, 13 Nov 2015 20:11:47 -0700
Subject: Question about math.pi is mutable
In-Reply-To: <5641C0EC.8010905@rece.vub.ac.be>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me> <857flujwy7.fsf@benfinney.id.au>
 <5640B28C.6050408@rece.vub.ac.be> <858u66g39k.fsf@benfinney.id.au>
 <5641C0EC.8010905@rece.vub.ac.be>
Message-ID: <5646A673.2060201@gmail.com>

On 11/10/2015 03:03 AM, Antoon Pardon wrote:
> Op 10-11-15 om 00:29 schreef Ben Finney:
>>
>> Who is doing what to whom? The user of the library isn't doing anything
>> to the library author, so what is it the library author would consent
>> to? Instead, you seem to be trying to assert a *power* of the library
>> author to restrict the library user. Such a power is not granted by
>> Python.
> 
> Python is not at liberty to grant or deny such a power. Python is just
> a vehicle in which code is written. The author of a library can restrict
> its use anyway he sees fit.

No he cannot, outside the bounds of copyright law.  Why would you think
otherwise?  The only document that binds the end user in any way is the
copyright license, unless some other formal contract has been arranged.

>> Instead, the library author is obliged to treat the library user as an
>> adult who consents to the freedoms inherent to Python's design, and to
>> not restrict their use of the library needlessly.
> 
> There is no such obligation. And if it was an obligation, you can hardly
> talk about consenting. Consenting adults mean that either party can
> decide on conditions. Once one party is obligated it is no longer consenting.

You are correct there is no obligation, but nor does Python empower the
library developer.   He may attempt obfuscation or other means to
control the use of his library of course, but only copyright grants him
legal authority of any kind.



From ian.g.kelly at gmail.com  Fri Nov 13 22:45:31 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 20:45:31 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
Message-ID: <CALwzidnvRe-4o9eHN4iB9vmmqeqzo8K-_kKnh__4yfcgENj1-Q@mail.gmail.com>

On Nov 13, 2015 8:03 PM, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Sat, Nov 14, 2015 at 1:40 PM, Steven D'Aprano <steve at pearwood.info>
wrote:
> > On Sat, 14 Nov 2015 09:42 am, Chris Angelico wrote:
> >
> >> However, this is a reasonable call for the abolition of unary plus...
> >
> > The only way you'll take unary plus out of Python is by prying it from
my
> > cold, dead hands.
> >
> >
> > BTW, unary minus suffers from the same "problem":
> >
> > x =- y  # oops, meant x -= y
> >
> > If anything, this is an argument against the augmented assignment
> > short-cuts, rather than the operators.
>
> Yes, unary minus has the same issue - but it's a lot more important
> than unary plus is. In ECMAScript, unary plus means "force this to be
> a number"; what's its purpose in Python?

It forces a Counter to contain only positive counts?


From ian.g.kelly at gmail.com  Fri Nov 13 22:48:50 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 20:48:50 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
Message-ID: <CALwzidnfzp-1hQPwHg_mmkN5LwBqCnR3Qs=v0OyhdWNrL3SWvg@mail.gmail.com>

On Nov 13, 2015 8:03 PM, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Sat, Nov 14, 2015 at 1:40 PM, Steven D'Aprano <steve at pearwood.info>
wrote:
> > On Sat, 14 Nov 2015 09:42 am, Chris Angelico wrote:
> >
> >> However, this is a reasonable call for the abolition of unary plus...
> >
> > The only way you'll take unary plus out of Python is by prying it from
my
> > cold, dead hands.
> >
> >
> > BTW, unary minus suffers from the same "problem":
> >
> > x =- y  # oops, meant x -= y
> >
> > If anything, this is an argument against the augmented assignment
> > short-cuts, rather than the operators.
>
> Yes, unary minus has the same issue - but it's a lot more important
> than unary plus is. In ECMAScript, unary plus means "force this to be
> a number"; what's its purpose in Python?

I'm not sure "force this to be a number" is really a justification. Without
it you could just use - - (but be careful not to write that as --) in the
manner of using !! as "force to boolean". Or just call Number().


From rosuav at gmail.com  Fri Nov 13 22:56:36 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 14:56:36 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CALwzidnvRe-4o9eHN4iB9vmmqeqzo8K-_kKnh__4yfcgENj1-Q@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
 <CALwzidnvRe-4o9eHN4iB9vmmqeqzo8K-_kKnh__4yfcgENj1-Q@mail.gmail.com>
Message-ID: <CAPTjJmrbwiHRnFi8MFoHeH5ihgkNe83ESTpOS830ZWcK-tyVpQ@mail.gmail.com>

On Sat, Nov 14, 2015 at 2:45 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> Yes, unary minus has the same issue - but it's a lot more important
>> than unary plus is. In ECMAScript, unary plus means "force this to be
>> a number"; what's its purpose in Python?
>
> It forces a Counter to contain only positive counts?

Did not know that, and would not have gone looking for it. If Python
hadn't had a unary plus operator, Counter would have managed in some
other way, without being materially impacted by it.

ChrisA


From rosuav at gmail.com  Fri Nov 13 22:57:43 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 14 Nov 2015 14:57:43 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CALwzidnfzp-1hQPwHg_mmkN5LwBqCnR3Qs=v0OyhdWNrL3SWvg@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <CAPTjJmoAGfTM6NWS4=FyRMdOUnOzFXnTbnHraFjngxuCFdMUew@mail.gmail.com>
 <CALwzidnfzp-1hQPwHg_mmkN5LwBqCnR3Qs=v0OyhdWNrL3SWvg@mail.gmail.com>
Message-ID: <CAPTjJmqbfuZQzR5knB8g6KVB2w7jXhT--xtxi28K_WproiEGDw@mail.gmail.com>

On Sat, Nov 14, 2015 at 2:48 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> Yes, unary minus has the same issue - but it's a lot more important
>> than unary plus is. In ECMAScript, unary plus means "force this to be
>> a number"; what's its purpose in Python?
>
> I'm not sure "force this to be a number" is really a justification. Without
> it you could just use - - (but be careful not to write that as --) in the
> manner of using !! as "force to boolean". Or just call Number().

I don't use it myself, but I saw something about asm.js that
demonstrated the use of "x = +x;" to mean "x is a number", and "x =
x|0;" to mean "x is an integer".

ChrisA


From ian.g.kelly at gmail.com  Fri Nov 13 22:58:04 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 13 Nov 2015 20:58:04 -0700
Subject: find which Python libraries are most influential in scientific
 research
In-Reply-To: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>
References: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>
Message-ID: <CALwzidkkDmidd0EcSgE1zrS0U=yfdawosOeAos1Tum2ffvEsCA@mail.gmail.com>

On Nov 9, 2015 7:41 PM, "Heather Piwowar" <hpiwowar at gmail.com> wrote:
>
> Today's scientists often turn to Python to run analysis, simulation, and
other sciency tasks.
>
> That makes us wonder: which Python libraries are most influential in
scientific research?
>
> We just released a tool (built in Python, of course) to answer that
question. It's called Depsy [1], it's funded by the US National Science
Foundation, and we'd love your comments.
>
> For more information, see our blog post [2] and paper [3].  The
scientific/engineering tag is a great place to start exploring [4].
>
> Heather Piwowar and Jason Priem
>
> 1. http://depsy.org
> 2. http://blog.impactstory.org/introducing-depsy
> 3.
https://github.com/Impactstory/depsy-research/blob/master/introducing_depsy.md
> 4. http://depsy.org/tag/scientific%252Fengineering

FYI, the depsy.org site is completely unusable on my Android phone.


From tjreedy at udel.edu  Sat Nov 14 00:38:41 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Sat, 14 Nov 2015 00:38:41 -0500
Subject: find which Python libraries are most influential in scientific
 research
In-Reply-To: <CALwzidkkDmidd0EcSgE1zrS0U=yfdawosOeAos1Tum2ffvEsCA@mail.gmail.com>
References: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>
 <CALwzidkkDmidd0EcSgE1zrS0U=yfdawosOeAos1Tum2ffvEsCA@mail.gmail.com>
Message-ID: <n26hd5$d04$1@ger.gmane.org>

On 11/13/2015 10:58 PM, Ian Kelly wrote:
> On Nov 9, 2015 7:41 PM, "Heather Piwowar" <hpiwowar at gmail.com> wrote:
>>
>> Today's scientists often turn to Python to run analysis, simulation, and
> other sciency tasks.
>>
>> That makes us wonder: which Python libraries are most influential in
> scientific research?

Numpy, scipy, ?, ?, ?, ...

>> We just released a tool (built in Python, of course) to answer that
> question. It's called Depsy [1], it's funded by the US National Science
> Foundation, and we'd love your comments.
>>
>> For more information, see our blog post [2] and paper [3].  The
> scientific/engineering tag is a great place to start exploring [4].
>>
>> Heather Piwowar and Jason Priem
>>
>> 1. http://depsy.org
>> 2. http://blog.impactstory.org/introducing-depsy
>> 3.
> https://github.com/Impactstory/depsy-research/blob/master/introducing_depsy.md
>> 4. http://depsy.org/tag/scientific%252Fengineering
>
> FYI, the depsy.org site is completely unusable on my Android phone.

Ditto Win10, Firefox.


-- 
Terry Jan Reedy



From steve at pearwood.info  Sat Nov 14 00:40:41 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 14 Nov 2015 16:40:41 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
Message-ID: <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>

On Sat, 14 Nov 2015 02:01 pm, Chris Angelico wrote:

> On Sat, Nov 14, 2015 at 1:40 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> On Sat, 14 Nov 2015 09:42 am, Chris Angelico wrote:
>>
>>> However, this is a reasonable call for the abolition of unary plus...
>>
>> The only way you'll take unary plus out of Python is by prying it from my
>> cold, dead hands.
>>
>>
>> BTW, unary minus suffers from the same "problem":
>>
>> x =- y  # oops, meant x -= y
>>
>> If anything, this is an argument against the augmented assignment
>> short-cuts, rather than the operators.
> 
> Yes, unary minus has the same issue - but it's a lot more important
> than unary plus is. In ECMAScript, unary plus means "force this to be
> a number"; what's its purpose in Python?


Python has operator overloading, so it can be anything you want it to be.
E.g. you might have a DSL where +feature turns something on and -feature
turns it off.


Decimal uses it to force the current precision and rounding, regardless of
what the number was initiated to:


py> from decimal import *
py> setcontext(Context(prec=5))
py> d = Decimal("12.34567890")
py> print(d, +d)
12.34567890 12.346


Counter uses it to strip zero and negative counts:


py> from collections import Counter
py> d = Counter(a=3, b=-3)
py> print(d)
Counter({'a': 3, 'b': -3})
py> print(+d)
Counter({'a': 3})


I would expect that symbolic maths software like Sympy probably has use of a
unary plus operator, but I'm not sure.


It's probably too late now, but if I had designed the Fraction class, I
would have made it inherit from a pure Rational class that didn't
automatically normalise (there are interesting operations that rely on
distinguishing fractions like 1/2 and 2/4), and have + perform
normalisation:

x = Rational(2, 4)
print(x, +x)
=> prints 2/4 1/2


Likewise one might use unary plus to normalise polar or cylindrical
coordinates, etc.

I might consider stealing an idea from Perl and Javascript, and have unary
plus convert strings to a number:

+"123" 
=> returns int 123
+"1.23"
=> returns float 1.23



-- 
Steven



From steve at pearwood.info  Sat Nov 14 01:05:43 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sat, 14 Nov 2015 17:05:43 +1100
Subject: find which Python libraries are most influential in scientific
 research
References: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>
 <mailman.320.1447473487.16136.python-list@python.org>
Message-ID: <5646cf39$0$1610$c3e8da3$5496439d@news.astraweb.com>

On Sat, 14 Nov 2015 02:58 pm, Ian Kelly wrote:

> FYI, the depsy.org site is completely unusable on my Android phone.

On Firefox under Linux, the page comes up blank.

If I use the NoScript plugin to allow Javascript from the despy.org site,
the page now takes twice as long to load, and still comes up blank.

If I then tell NoScript to allow Javascript from angular-io.github.io, it
eventually loads an extremely garish, multi-coloured page with no dynamic
content. As far as I can see, everything is static text and links, with a
very few GIANT icons, which makes the dependency on Javascript *completely*
unnecessary and quite obnoxious.

For the record, the page contains just under 350 words, and loading it
requires 21 web requests for 947.40 KB of data, or equivalent to
approximately 2700 bytes per word.

Between the difficulty of getting the page to display, and the unfortunate
look of the page once it actually does (it looks like it was designed for
an audience of five year olds, with brightly coloured purple, red, blue,
green, yellow backgrounds and giant-sized text), I wouldn't be in a rush to
explore the project any further.

I wish the authors good luck with the project, but they're not doing
themselves (or us) any favours with the design of the webpage.



-- 
Steven



From lac at openend.se  Sat Nov 14 02:37:50 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 14 Nov 2015 08:37:50 +0100
Subject: find which Python libraries are most influential in scientific
 research
In-Reply-To: <n26hd5$d04$1@ger.gmane.org>
References: <06e7d84d-7e49-4160-b42e-a6911640d9e8@googlegroups.com>
 <CALwzidkkDmidd0EcSgE1zrS0U=yfdawosOeAos1Tum2ffvEsCA@mail.gmail.com>
 <n26hd5$d04$1@ger.gmane.org>
Message-ID: <201511140737.tAE7bpC5016573@fido.openend.se>

In a message of Sat, 14 Nov 2015 00:38:41 -0500, Terry Reedy writes:
>On 11/13/2015 10:58 PM, Ian Kelly wrote:
>> On Nov 9, 2015 7:41 PM, "Heather Piwowar" <hpiwowar at gmail.com> wrote:
>>>
>>> Today's scientists often turn to Python to run analysis, simulation, and
>> other sciency tasks.
>>>
>>> That makes us wonder: which Python libraries are most influential in
>> scientific research?
>
>Numpy, scipy, ?, ?, ?, ...

I'd put money on

matplotlib
pandas


>>> We just released a tool (built in Python, of course) to answer that
>> question. It's called Depsy [1], it's funded by the US National Science
>> Foundation, and we'd love your comments.
>>>
>>> For more information, see our blog post [2] and paper [3].  The
>> scientific/engineering tag is a great place to start exploring [4].
>>>
>>> Heather Piwowar and Jason Priem
>>>
>>> 1. http://depsy.org
>>> 2. http://blog.impactstory.org/introducing-depsy
>>> 3.
>> https://github.com/Impactstory/depsy-research/blob/master/introducing_depsy.md
>>> 4. http://depsy.org/tag/scientific%252Fengineering
>>
>> FYI, the depsy.org site is completely unusable on my Android phone.
>
>Ditto Win10, Firefox.

Not looking good under FF here with debian unstable and a smallish
laptop screen, either.

Laura

>-- 
>Terry Jan Reedy



From auriocus at gmx.de  Sat Nov 14 03:14:09 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 14 Nov 2015 09:14:09 +0100
Subject: More tkinter Madness
In-Reply-To: <56465FE2.40701@tundraware.com>
References: <708dhc-3pf1.ln1@oceanview.tundraware.com>
 <mailman.252.1447295160.16136.python-list@python.org>
 <v8nfhc-epd2.ln1@oceanview.tundraware.com>
 <mailman.283.1447389990.16136.python-list@python.org>
 <fr9ghc-c5i2.ln1@oceanview.tundraware.com> <n2400v$h96$1@dont-email.me>
 <0dphhc-ntf.ln1@oceanview.tundraware.com> <n25klu$rij$1@dont-email.me>
 <56465FE2.40701@tundraware.com>
Message-ID: <n26qc8$8fl$1@dont-email.me>

Am 13.11.15 um 23:10 schrieb Tim Daneliuk:
> On 11/13/2015 03:30 PM, Christian Gollwitzer wrote:
>> Am 13.11.15 um 20:14 schrieb Tim Daneliuk:
>>> On 11/13/2015 12:32 AM, Christian Gollwitzer wrote:
>>>> Apfelkiste:Sources chris$
>>>
>>> Well, I get window and when I do this:
>>>
>>> pack [button .b -text Hello -command exit]
>>>
>>> Nothing appears.
>>
>> No error, nothing? Just to be sure, you haven't closed the empty
>> window, that appeared when you typed "wish"? and copied the command
>> into the wish prompt?
>>
>>> tkinter appears borked I have reinstalled once already, will try
>>> again
>>
>> This is using pure Tcl/Tk. If it is not working, reinstall the
>> corresponding packages in your distro. tkinter is merely the Python
>> interface to those.
>>
>> Christian
>
> Yep tcl/tk is the culprit, but reinstalling has not helped.

I am still not understanding, what actually happened. Does the wish 
shell crash, does it simply exit, or hang? Is there no error message?

You can try if a different/newer version works for your setup. For 
example, you could download a copy of a tclkit from here:

	http://tclkits.rkeene.org/fossil/wiki/Downloads

presumably the 8.6.3 version for RHEL5, and try if it runs a script like 
this

# the next line should make an empty window appear
package require Tk
# this line should create the button in it
pack [button .b -text Hello -command exit]

If this does work, then installing Tcl/Tk from scratch (i.e. copmiling 
yourself) might work.
(Unfortunately, you cannot make tkinter work with a Tclkit)

	Christian


From cs at zip.com.au  Sat Nov 14 03:59:34 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Sat, 14 Nov 2015 19:59:34 +1100
Subject: find which Python libraries are most influential in scientific
 research
In-Reply-To: <201511140737.tAE7bpC5016573@fido.openend.se>
References: <201511140737.tAE7bpC5016573@fido.openend.se>
Message-ID: <20151114085934.GA82128@cskk.homeip.net>

On 14Nov2015 08:37, Laura Creighton <lac at openend.se> wrote:
>In a message of Sat, 14 Nov 2015 00:38:41 -0500, Terry Reedy writes:
>>On 11/13/2015 10:58 PM, Ian Kelly wrote:
>>> On Nov 9, 2015 7:41 PM, "Heather Piwowar" <hpiwowar at gmail.com> wrote:
>>>> 4. http://depsy.org/tag/scientific%252Fengineering
>>>
>>> FYI, the depsy.org site is completely unusable on my Android phone.
>>
>>Ditto Win10, Firefox.
>
>Not looking good under FF here with debian unstable and a smallish
>laptop screen, either.

Ditto FF on Mac OSX. Totally blank. Renders ok on Safari. If I enable several 
sites' JavaScript it loads in Firefox, but there's nothing on the page that 
looks like it should need any JavaScript (hmm, some mouseovers but I'm pretty 
sure that can be mediated entirely in CSS, perhaps less "smoothly").

There does seems to be a nice long list of relevant Python packages listed 
there though.

Cheers,
Cameron Simpson <cs at zip.com.au>


From df at see.replyto.invalid  Sat Nov 14 04:14:10 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Sat, 14 Nov 2015 09:14:10 +0000
Subject: What is '@' for
References: <b4254670-28c9-4e2c-a221-a27c0d6f62e9@googlegroups.com>
Message-ID: <snud4bpm6d7cf6lg20q1a5675uc25av1kg@4ax.com>

fl <rxjwg98 at gmail.com> wrote:

>I read the following code snippet. A question is here about '@'.
>I don't find the answer online yet.

I recommend this:

"Understanding Python Decorators in 12 Easy Steps!"

http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/


From Cecil at decebal.nl  Sat Nov 14 06:51:38 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Sat, 14 Nov 2015 12:51:38 +0100
Subject: Trying out Kivy
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
 <mailman.300.1447444435.16136.python-list@python.org>
 <87lha11wz4.fsf@Equus.decebal.nl>
Message-ID: <87d1vc23zp.fsf@Equus.decebal.nl>

On Friday 13 Nov 2015 21:10 CET, Cecil Westerhof wrote:

> On Friday 13 Nov 2015 20:53 CET, Michael Torrie wrote:
>
>> On 11/13/2015 11:30 AM, Cecil Westerhof wrote:
>>> On Friday 13 Nov 2015 18:21 CET, Michael Torrie wrote:
>>>
>>>> On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
>>>>> I tried to install pygame and PIL with pip3, but that did not
>>>>> find anything.
>>>>
>>>> The replacement for PIL is called Pillow. I'm not sure if it's a
>>>> drop-in replacement or not. If it's not, then you'd have to
>>>> modify Kivy to import from Pillow. Pillow does support Python3.
>>>
>>> After installing Pillow the error about PIL disappeared, but I got
>>> new errors about bcm and x11.
>>
>> Traceback?
>
> Purge log fired. Analysing... Purge finished! [INFO ] [Logger ]
> Record log in /home/cecil/.kivy/logs/kivy_15-11-13_28.txt [INFO ]
> [Kivy ] v1.9.0 [INFO ] [Python ] v3.4.1 (default, May 23 2014,
> 17:48:28) [GCC] [INFO ] [Factory ] 173 symbols loaded [INFO ] [Image
> ] Providers: img_tex, img_dds, img_gif, img_pil (img_pygame,
> img_ffpyplayer ignored) [INFO ] [Text ] Provider:
> pil(['text_pygame'] ignored) [CRITICAL ] [Window ] Unable to find
> any valuable Window provider at all! egl_rpi - ImportError: cannot
> import name 'bcm' File
> "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57,
> in core_select_lib fromlist=[modulename], level=0) File
> "/usr/lib64/python3.4/site-packages/kivy/core/window/window_egl_rpi.py",
> line 12, in <module> from kivy.lib.vidcore_lite import bcm, egl
>
> pygame - ImportError: No module named 'pygame' File
> "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57,
> in core_select_lib fromlist=[modulename], level=0) File
> "/usr/lib64/python3.4/site-packages/kivy/core/window/window_pygame.py",
> line 8, in <module> import pygame
>
> x11 - ImportError: No module named 'kivy.core.window.window_x11'
> File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py",
> line 57, in core_select_lib fromlist=[modulename], level=0)
>
> [CRITICAL ] [App ] Unable to get a Window, abort. Exception ignored
> in: 'kivy.properties.dpi2px' Traceback (most recent call last): File
> "/usr/lib64/python3.4/site-packages/kivy/utils.py", line 360, in
> __get__ retval = self.func(inst) File
> "/usr/lib64/python3.4/site-packages/kivy/metrics.py", line 169, in
> dpi EventLoop.ensure_window() File
> "/usr/lib64/python3.4/site-packages/kivy/base.py", line 126, in
> ensure_window sys.exit(1) SystemExit: 1 [CRITICAL ] [App ] Unable to
> get a Window, abort.
>
>
> I see a difference with python2. (Did not notice it before.) With
> python3 v1.9.0 is installed, but with python2 v1.8.0.
> [INFO              ] Kivy v1.8.0
>
> Maybe that is the problem?

I tried to install v1.8.0 with:
    pip3 install -I kivy==1.8.0

But that gives:
    building 'kivy.graphics.shader' extension

    gcc -pthread -Wno-unused-result -Werror=declaration-after-statement -DNDEBUG -fmessage-length=0 -grecord-gcc-switches -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -g -DOPENSSL_LOAD_CONF -fPIC -I/usr/include/python3.4m -c /tmp/pip_build_root/kivy/kivy/graphics/shader.c -o build/temp.linux-x86_64-3.4/tmp/pip_build_root/kivy/kivy/graphics/shader.o

    /tmp/pip_build_root/kivy/kivy/graphics/shader.c:1:2: error: #error Do not use this file, it is the result of a failed Cython compilation.

     #error Do not use this file, it is the result of a failed Cython compilation.

      ^



     Error compiling Cython file:

     ------------------------------------------------------------

     ...

                 vertex_format.last_shader = self

                 for i in xrange(vertex_format.vattr_count):

                     attr = &vertex_format.vattr[i]

                     if attr.per_vertex == 0:

                         continue

                     attr.index = glGetAttribLocation(self.program, <char *><bytes>attr.name)

                                                                   ^

     ------------------------------------------------------------



     kivy/graphics/shader.pyx:448:63: Casting temporary Python object to non-numeric non-Python type

     error: command 'gcc' failed with exit status 1

    ----------------------------------------
    Cleaning up...
    Command /usr/bin/python3 -c "import setuptools, tokenize;__file__='/tmp/pip_build_root/kivy/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-hvd8j0e_-record/install-rec

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From rxjwg98 at gmail.com  Sat Nov 14 07:10:33 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 04:10:33 -0800 (PST)
Subject: Where is decorator in this example code?
Message-ID: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>

Hi,

I am learning decorator following this link:

http://thecodeship.com/patterns/guide-to-python-function-decorators/

When I read decorator on class, I don't see decorator taking in effect.
In the following code snippet, there is the same print out if I comment out
two lines 'def p_decorate(func):' and '@p_decorate'.

Can you tell me what role of decorator in this code?


Thanks,

......
def p_decorate(func):
   def func_wrapper(self):
       return "<p>{0}</p>".format(func(self))
   return func_wrapper

class Person(object):
    def __init__(self):
        self.name = "John"
        self.family = "Doe"

    @p_decorate
    def get_fullname(self):
        return self.name+" "+self.family

my_person = Person()
print my_person.get_fullname()


From rxjwg98 at gmail.com  Sat Nov 14 07:13:19 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 04:13:19 -0800 (PST)
Subject: Where is decorator in this example code?
In-Reply-To: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>
References: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>
Message-ID: <bf73e0ab-2394-42a6-bb53-dd73be3897e3@googlegroups.com>

On Saturday, November 14, 2015 at 7:11:11 AM UTC-5, fl wrote:
> Hi,
> 
> I am learning decorator following this link:
> 
> http://thecodeship.com/patterns/guide-to-python-function-decorators/
> 
> When I read decorator on class, I don't see decorator taking in effect.
> In the following code snippet, there is the same print out if I comment out
> two lines 'def p_decorate(func):' and '@p_decorate'.
> 
> Can you tell me what role of decorator in this code?
> 
> 
> Thanks,
> 
> ......
> def p_decorate(func):
>    def func_wrapper(self):
>        return "<p>{0}</p>".format(func(self))
>    return func_wrapper
> 
> class Person(object):
>     def __init__(self):
>         self.name = "John"
>         self.family = "Doe"
> 
>     @p_decorate
>     def get_fullname(self):
>         return self.name+" "+self.family
> 
> my_person = Person()
> print my_person.get_fullname()

My OP may not be clear enough. Here is the key question. After the function
definition, there is no obvious decorator application in the function call:

my_person = Person()
print my_person.get_fullname()

Where is the difference between the non-decorator and decorator in this 
example?

Thanks,


From kwpolska at gmail.com  Sat Nov 14 07:37:44 2015
From: kwpolska at gmail.com (Chris Warrick)
Date: Sat, 14 Nov 2015 13:37:44 +0100
Subject: Where is decorator in this example code?
In-Reply-To: <bf73e0ab-2394-42a6-bb53-dd73be3897e3@googlegroups.com>
References: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>
 <bf73e0ab-2394-42a6-bb53-dd73be3897e3@googlegroups.com>
Message-ID: <CAMw+j7L+98D0X4a+owKUBjPZtOa=mTz+wCuG+_TC82+FPhhkmQ@mail.gmail.com>

On 14 November 2015 at 13:13, fl <rxjwg98 at gmail.com> wrote:
> On Saturday, November 14, 2015 at 7:11:11 AM UTC-5, fl wrote:
>> Hi,
>>
>> I am learning decorator following this link:
>>
>> http://thecodeship.com/patterns/guide-to-python-function-decorators/
>>
>> When I read decorator on class, I don't see decorator taking in effect.
>> In the following code snippet, there is the same print out if I comment out
>> two lines 'def p_decorate(func):' and '@p_decorate'.
>>
>> Can you tell me what role of decorator in this code?
[snip code]
>
> My OP may not be clear enough. Here is the key question. After the function
> definition, there is no obvious decorator application in the function call:
>
> my_person = Person()
> print my_person.get_fullname()
>
> Where is the difference between the non-decorator and decorator in this
> example?
>
> Thanks,
> --
> https://mail.python.org/mailman/listinfo/python-list

Have you tried executing the code with and without the decorator?

$ python2 without-decorator.py
John Doe
$ python2 with-decorator.py
<p>John Doe</p>

Basically, the decorator wraps the output of your get_fullname
function with HTML <p> tags.

(Running code examples is a great way to understand them.)

-- 
Chris Warrick <https://chriswarrick.com/>
PGP: 5EAAEA16


From wabayang at gmail.com  Sat Nov 14 07:42:57 2015
From: wabayang at gmail.com (bayang)
Date: Sat, 14 Nov 2015 13:42:57 +0100
Subject: Trying out Kivy
In-Reply-To: <87d1vc23zp.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
 <mailman.300.1447444435.16136.python-list@python.org>
 <87lha11wz4.fsf@Equus.decebal.nl> <87d1vc23zp.fsf@Equus.decebal.nl>
Message-ID: <CALFNb6JRAgep=YfjXUOzE6vTP8EjaA1X7DcJJM4B=ZgWkvEchg@mail.gmail.com>

Le 14 nov. 2015 13:00, "Cecil Westerhof" <Cecil at decebal.nl> a ?crit :
>
> On Friday 13 Nov 2015 21:10 CET, Cecil Westerhof wrote:
>
> > On Friday 13 Nov 2015 20:53 CET, Michael Torrie wrote:
> >
> >> On 11/13/2015 11:30 AM, Cecil Westerhof wrote:
> >>> On Friday 13 Nov 2015 18:21 CET, Michael Torrie wrote:
> >>>
> >>>> On 11/13/2015 09:33 AM, Cecil Westerhof wrote:
> >>>>> I tried to install pygame and PIL with pip3, but that did not
> >>>>> find anything.
> >>>>
> >>>> The replacement for PIL is called Pillow. I'm not sure if it's a
> >>>> drop-in replacement or not. If it's not, then you'd have to
> >>>> modify Kivy to import from Pillow. Pillow does support Python3.
> >>>
> >>> After installing Pillow the error about PIL disappeared, but I got
> >>> new errors about bcm and x11.
> >>
> >> Traceback?
> >
> > Purge log fired. Analysing... Purge finished! [INFO ] [Logger ]
> > Record log in /home/cecil/.kivy/logs/kivy_15-11-13_28.txt [INFO ]
> > [Kivy ] v1.9.0 [INFO ] [Python ] v3.4.1 (default, May 23 2014,
> > 17:48:28) [GCC] [INFO ] [Factory ] 173 symbols loaded [INFO ] [Image
> > ] Providers: img_tex, img_dds, img_gif, img_pil (img_pygame,
> > img_ffpyplayer ignored) [INFO ] [Text ] Provider:
> > pil(['text_pygame'] ignored) [CRITICAL ] [Window ] Unable to find
> > any valuable Window provider at all! egl_rpi - ImportError: cannot
> > import name 'bcm' File
> > "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57,
> > in core_select_lib fromlist=[modulename], level=0) File
> > "/usr/lib64/python3.4/site-packages/kivy/core/window/window_egl_rpi.py",
> > line 12, in <module> from kivy.lib.vidcore_lite import bcm, egl
> >
> > pygame - ImportError: No module named 'pygame' File
> > "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py", line 57,
> > in core_select_lib fromlist=[modulename], level=0) File
> > "/usr/lib64/python3.4/site-packages/kivy/core/window/window_pygame.py",
> > line 8, in <module> import pygame
> >
> > x11 - ImportError: No module named 'kivy.core.window.window_x11'
> > File "/usr/lib64/python3.4/site-packages/kivy/core/__init__.py",
> > line 57, in core_select_lib fromlist=[modulename], level=0)
> >
> > [CRITICAL ] [App ] Unable to get a Window, abort. Exception ignored
> > in: 'kivy.properties.dpi2px' Traceback (most recent call last): File
> > "/usr/lib64/python3.4/site-packages/kivy/utils.py", line 360, in
> > __get__ retval = self.func(inst) File
> > "/usr/lib64/python3.4/site-packages/kivy/metrics.py", line 169, in
> > dpi EventLoop.ensure_window() File
> > "/usr/lib64/python3.4/site-packages/kivy/base.py", line 126, in
> > ensure_window sys.exit(1) SystemExit: 1 [CRITICAL ] [App ] Unable to
> > get a Window, abort.
> >
> >
> > I see a difference with python2. (Did not notice it before.) With
> > python3 v1.9.0 is installed, but with python2 v1.8.0.
> > [INFO              ] Kivy v1.8.0
> >
> > Maybe that is the problem?
>
> I tried to install v1.8.0 with:
>     pip3 install -I kivy==1.8.0
>
> But that gives:
>     building 'kivy.graphics.shader' extension
>
>     gcc -pthread -Wno-unused-result -Werror=declaration-after-statement
-DNDEBUG -fmessage-length=0 -grecord-gcc-switches -O2 -Wall
-D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables
-fasynchronous-unwind-tables -g -DOPENSSL_LOAD_CONF -fPIC
-I/usr/include/python3.4m -c
/tmp/pip_build_root/kivy/kivy/graphics/shader.c -o
build/temp.linux-x86_64-3.4/tmp/pip_build_root/kivy/kivy/graphics/shader.o
>
>     /tmp/pip_build_root/kivy/kivy/graphics/shader.c:1:2: error: #error Do
not use this file, it is the result of a failed Cython compilation.
>
>      #error Do not use this file, it is the result of a failed Cython
compilation.
>
>       ^
>
>
>
>      Error compiling Cython file:
>
>      ------------------------------------------------------------
>
>      ...
>
>                  vertex_format.last_shader = self
>
>                  for i in xrange(vertex_format.vattr_count):
>
>                      attr = &vertex_format.vattr[i]
>
>                      if attr.per_vertex == 0:
>
>                          continue
>
>                      attr.index = glGetAttribLocation(self.program, <char
*><bytes>attr.name)
>
>                                                                    ^
>
>      ------------------------------------------------------------
>
>
>
>      kivy/graphics/shader.pyx:448:63: Casting temporary Python object to
non-numeric non-Python type
>
>      error: command 'gcc' failed with exit status 1
>
>     ----------------------------------------
>     Cleaning up...
>     Command /usr/bin/python3 -c "import setuptools,
tokenize;__file__='/tmp/pip_build_root/kivy/setup.py';exec(compile(getattr(tokenize,
'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))"
install --record /tmp/pip-hvd8j0e_-record/install-rec
>
> --
> Cecil Westerhof
> Senior Software Engineer
> LinkedIn: http://www.linkedin.com/in/cecilwesterhof
> --
> https://mail.python.org/mailman/listinfo/python-list

The latest cython version is for kivy 1.9. For kivy 1.8 you must use an
older cython version.  Check kivy website. That's why you get compiling
errors


From johnzzhao at gmail.com  Sat Nov 14 09:26:29 2015
From: johnzzhao at gmail.com (John Zhao)
Date: Sat, 14 Nov 2015 06:26:29 -0800 (PST)
Subject: Persist objects in a  LIST
Message-ID: <0cb1bcda-54d5-4cc7-bd23-f86f7f10ee28@googlegroups.com>

I am new to Python, and just learned that Python list is just a container of object reference.   

In the example below,  bDict needs to be just a temporary object, constructed at run time and then be added to aList.       At the end, aList will contain n objects.    

Is there a clean way to do that?

Many thanks, 

John

$ ipython
WARNING: IPython History requires SQLite, your history will not be saved
WARNING: Readline services not available or not loaded.
WARNING: The auto-indent feature requires the readline library
Python 2.7.9 (default, Sep  5 2015, 07:20:36)
Type "copyright", "credits" or "license" for more information.

IPython 4.0.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.
In [1]: aList = []
In [2]: bDict = {}
In [3]: bDict['instance_name']='SERVER_TIER'
In [4]: aList.append(bDict)
In [5]: print aList
[{'instance_name': 'SERVER_TIER'}]
In [6]: bDict.clear()
In [7]: print aList
[{}]


From rxjwg98 at gmail.com  Sat Nov 14 09:46:16 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 06:46:16 -0800 (PST)
Subject: Where is decorator in this example code?
In-Reply-To: <mailman.324.1447504672.16136.python-list@python.org>
References: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>
 <bf73e0ab-2394-42a6-bb53-dd73be3897e3@googlegroups.com>
 <mailman.324.1447504672.16136.python-list@python.org>
Message-ID: <e1a11976-9fb5-4df1-a84e-73fd76a17ebe@googlegroups.com>

On Saturday, November 14, 2015 at 7:38:09 AM UTC-5, Chris Warrick wrote:
> On 14 November 2015 at 13:13, fl <rx**g98 at gmail.com> wrote:
> > On Saturday, November 14, 2015 at 7:11:11 AM UTC-5, fl wrote:
> >> Hi,
> >>
> >> I am learning decorator following this link:
> >>
> >> http://thecodeship.com/patterns/guide-to-python-function-decorators/
> >>
> >> When I read decorator on class, I don't see decorator taking in effect.
> >> In the following code snippet, there is the same print out if I comment out
> >> two lines 'def p_decorate(func):' and '@p_decorate'.
> >>
> >> Can you tell me what role of decorator in this code?
> [snip code]
> >
> > My OP may not be clear enough. Here is the key question. After the function
> > definition, there is no obvious decorator application in the function call:
> >
> > my_person = Person()
> > print my_person.get_fullname()
> >
> > Where is the difference between the non-decorator and decorator in this
> > example?
> >
> > Thanks,
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Have you tried executing the code with and without the decorator?
> 
> $ python2 without-decorator.py
> John Doe
> $ python2 with-decorator.py
> <p>John Doe</p>
> 
> Basically, the decorator wraps the output of your get_fullname
> function with HTML <p> tags.
> 
> (Running code examples is a great way to understand them.)
> 
> -- 
> Chris Warrick <https://chriswarrick.com/>
> PGP: 5EAAEA16

Thanks. I did run the code, but I did not check the difference carefully
between them.

A following problem now is about the args in class decorate. I do not see
args and kwargs are transferred by get_fullname(self).


If I change 

return "<p>{0}</p>".format(func(*args, **kwargs))

to

return "<p>{0}</p>".format(func(*args))

The outputs are the same.

But it is quite different if it is changed to:

return "<p>{0}</p>".format(func)

What roles are args and kwargs? I know C language.
For Python here, I don't see some rules on the args. 

Thanks again.


/////////////
def p_decorate(func):
   def func_wrapper(*args, **kwargs):
       return "<p>{0}</p>".format(func(*args, **kwargs))
   return func_wrapper

class Person(object):
    def __init__(self):
        self.name = "John"
        self.family = "Doe"

    @p_decorate
    def get_fullname(self):
        return self.name+" "+self.family

my_person = Person()

print my_person.get_fullname()


From antoon.pardon at rece.vub.ac.be  Sat Nov 14 10:02:00 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Sat, 14 Nov 2015 16:02:00 +0100
Subject: Question about math.pi is mutable
In-Reply-To: <5646A673.2060201@gmail.com>
References: <mailman.77.1446804678.16136.python-list@python.org>
 <n1i6d4$bfg$1@dont-email.me>
 <mailman.90.1446826322.16136.python-list@python.org>
 <n1iv1c$hst$1@dont-email.me> <857flujwy7.fsf@benfinney.id.au>
 <5640B28C.6050408@rece.vub.ac.be> <858u66g39k.fsf@benfinney.id.au>
 <5641C0EC.8010905@rece.vub.ac.be> <5646A673.2060201@gmail.com>
Message-ID: <56474CE8.7020908@rece.vub.ac.be>

Op 14-11-15 om 04:11 schreef Michael Torrie:
> On 11/10/2015 03:03 AM, Antoon Pardon wrote:
>> Op 10-11-15 om 00:29 schreef Ben Finney:
>>>
>>> Who is doing what to whom? The user of the library isn't doing anything
>>> to the library author, so what is it the library author would consent
>>> to? Instead, you seem to be trying to assert a *power* of the library
>>> author to restrict the library user. Such a power is not granted by
>>> Python.
>>
>> Python is not at liberty to grant or deny such a power. Python is just
>> a vehicle in which code is written. The author of a library can restrict
>> its use anyway he sees fit.
> 
> No he cannot, outside the bounds of copyright law.  Why would you think
> otherwise?  The only document that binds the end user in any way is the
> copyright license, unless some other formal contract has been arranged.

You haven't contradicted me in any way. What you are talking about here
is in what form those restrictions must be published. I am talking about
the restrictions the author can put in a license.

-- 
Antoon Pardon


From johnzzhao at gmail.com  Sat Nov 14 10:02:41 2015
From: johnzzhao at gmail.com (John Zhao)
Date: Sat, 14 Nov 2015 07:02:41 -0800 (PST)
Subject: Persist objects in a  LIST
In-Reply-To: <0cb1bcda-54d5-4cc7-bd23-f86f7f10ee28@googlegroups.com>
References: <0cb1bcda-54d5-4cc7-bd23-f86f7f10ee28@googlegroups.com>
Message-ID: <15f9fdeb-f4b4-4404-bccb-2e67a26035ed@googlegroups.com>

I found a solution.  replace  bDict.clear() with  bDict = {} 

thanks,

John


From ian.g.kelly at gmail.com  Sat Nov 14 10:43:13 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 14 Nov 2015 08:43:13 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidnYYiErH_ERYCszk6eyxcv13eV08=6PpXHDj25iSmre8Q@mail.gmail.com>

On Fri, Nov 13, 2015 at 10:40 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> Python has operator overloading, so it can be anything you want it to be.
> E.g. you might have a DSL where +feature turns something on and -feature
> turns it off.

By that argument we should also have operators ~, !, $, \, ? because
some hypothetical DSL might someday want to use them for something.

> Decimal uses it to force the current precision and rounding, regardless of
> what the number was initiated to:
>
> Counter uses it to strip zero and negative counts:
>
> I would expect that symbolic maths software like Sympy probably has use of a
> unary plus operator, but I'm not sure.

Unary plus as normalization does not strike me as being very
intuitive. I never would have known about any of these if I hadn't
read the Counter case in the docs, and then I only remembered it
because it because it seemed janky. Unary minus on Counters is even
weirder, by the way: it first negates the signs of all the values, and
*then* normalizes by removing non-positive values. Who has ever needed
that?

For somebody reading one of these uses of unary plus in real code, I
imagine it would be a bit of a WTF moment if it's the first time
they've encountered it. I don't recall ever seeing any code that
actually used this, though.

> I might consider stealing an idea from Perl and Javascript, and have unary
> plus convert strings to a number:
>
> +"123"
> => returns int 123
> +"1.23"
> => returns float 1.23

Eww.


From torriem at gmail.com  Sat Nov 14 10:43:30 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 14 Nov 2015 08:43:30 -0700
Subject: Trying out Kivy
In-Reply-To: <87d1vc23zp.fsf@Equus.decebal.nl>
References: <871tbt3lml.fsf@Equus.decebal.nl>
 <mailman.294.1447435298.16136.python-list@python.org>
 <87pozd21nb.fsf@Equus.decebal.nl>
 <mailman.300.1447444435.16136.python-list@python.org>
 <87lha11wz4.fsf@Equus.decebal.nl> <87d1vc23zp.fsf@Equus.decebal.nl>
Message-ID: <564756A2.2080609@gmail.com>

On 11/14/2015 04:51 AM, Cecil Westerhof wrote:
> I tried to install v1.8.0 with:
>     pip3 install -I kivy==1.8.0

Why are you trying to install the non-current version of kivy?

Did you install pygame successfully?



From ian.g.kelly at gmail.com  Sat Nov 14 11:08:33 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 14 Nov 2015 09:08:33 -0700
Subject: Where is decorator in this example code?
In-Reply-To: <e1a11976-9fb5-4df1-a84e-73fd76a17ebe@googlegroups.com>
References: <3800f31d-e570-4492-9dcf-58105c140b2b@googlegroups.com>
 <bf73e0ab-2394-42a6-bb53-dd73be3897e3@googlegroups.com>
 <mailman.324.1447504672.16136.python-list@python.org>
 <e1a11976-9fb5-4df1-a84e-73fd76a17ebe@googlegroups.com>
Message-ID: <CALwzidnUF8aTTrvKfJ+ZskQn+_R-UkzQdKgU7-MQFD=mnjGLBg@mail.gmail.com>

On Sat, Nov 14, 2015 at 7:46 AM, fl <rxjwg98 at gmail.com> wrote:
> A following problem now is about the args in class decorate. I do not see
> args and kwargs are transferred by get_fullname(self).
>
>
> If I change
>
> return "<p>{0}</p>".format(func(*args, **kwargs))
>
> to
>
> return "<p>{0}</p>".format(func(*args))
>
> The outputs are the same.
>
> But it is quite different if it is changed to:
>
> return "<p>{0}</p>".format(func)

In this case you're not even calling the function, so the thing that
you're formatting in the string is the function object itself.

> What roles are args and kwargs? I know C language.
> For Python here, I don't see some rules on the args.

They are Python's version of "varargs" or variadic arguments.

If a function parameter declaration is prefixed with *, then that
parameter will collect all the remaining positional arguments. For
example, with the function declaration "def f(a, b, *c):", f may be
called with two or more arguments. The first two arguments will be
assigned to a and b, and c will be a tuple containing all the
remaining arguments. It is customary but not necessary to name this
parameter "args".

You can also do the inverse when calling a function. If x is a list or
tuple, then calling f(x) will pass the sequence x to f as a single
argument, while calling f(*x) will pass the contents of x as
individual arguments.

Similarly, if a function parameter declaration is prefixed with **,
then that parameter will collect all the keyword arguments that have
not been assigned to other parameters, in a dict. It is customary but
not necessary to name this parameter "kwargs". And again you can also
do the inverse when calling a function: if x is a dict, then calling
f(x) will pass along the dict as a single argument, while calling
f(**x) will pass the contents of the dict as individual keyword
arguments.

So if you have a function like this:

    def f(*args, **kwargs):
        return g(*args, **kwargs)

This collects all the arguments that were passed to f, and passes them
along to g in the same manner they were supplied to f.

In your example, removing **kwargs appeared to do nothing because no
keyword arguments were actually passed in.


From vincent.vande.vyvre at telenet.be  Sat Nov 14 11:33:59 2015
From: vincent.vande.vyvre at telenet.be (Vincent Vande Vyvre)
Date: Sat, 14 Nov 2015 17:33:59 +0100
Subject: Persist objects in a LIST
In-Reply-To: <sale4b1mf366fhioarhastvbksjf0c9hfb@4ax.com>
References: <0cb1bcda-54d5-4cc7-bd23-f86f7f10ee28@googlegroups.com>
 <15f9fdeb-f4b4-4404-bccb-2e67a26035ed@googlegroups.com>
 <sale4b1mf366fhioarhastvbksjf0c9hfb@4ax.com>
Message-ID: <56476277.9010605@telenet.be>

Le 14/11/2015 16:39, Dennis Lee Bieber a ?crit :
> On Sat, 14 Nov 2015 07:02:41 -0800 (PST), John Zhao <johnzzhao at gmail.com>
> declaimed the following:
>
>> I found a solution.  replace  bDict.clear() with  bDict = {}
>>
> 	Which is creating a second, empty, dictionary and binding the name
> "bDict" to that new one.
>
> 	If all you want is to get rid of the name
>
> 		del bDict
>
> should suffice.
Not exactly.

 >>> l = []
 >>> d = {'key': 'val'}
 >>> l.append(d)
 >>> l
[{'key': 'val'}]
 >>> del d
 >>> l
[{'key': 'val'}]
 >>> del l[0]
 >>> l
[]
 >>>

Vince


From marko at pacujo.net  Sat Nov 14 11:52:56 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 14 Nov 2015 18:52:56 +0200
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
Message-ID: <87vb94ikuv.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> For somebody reading one of these uses of unary plus in real code, I
> imagine it would be a bit of a WTF moment if it's the first time
> they've encountered it. I don't recall ever seeing any code that
> actually used this, though.

What I don't understand is why there is a unary + but no unary /:

   -x ? 0 - x
   +x ? 0 + x
   /x ? 1 / x
   //x ? 1 // x
   *x ? 1 * x

You could write:

   r = //(//r1 + //r2 + //r3)

for

   r = 1 // (1//r1 + 1//r2 + 1//r3)

Actually, the real question is, is the unary - *really* so useful that
it merits existence or is it just something that was mindlessly copied
into programming languages from elementary school arithmetics?

BTW, Scheme's got the whole set:

    (- 3)
    => -3
    (- 3 2)
    => 1
    (- 3 2 1)
    => 0
    (/ 3)
    => 1/3
    (* 3)
    => 3
    (*)
    => 1

However, there's a tricky discontinuity:

    (apply - 3 '(2 1))
    => 0
    (apply - 3 '(2))
    => 1
    (apply - 3 '())
    => -3


Marko


From rosuav at gmail.com  Sat Nov 14 11:59:57 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 03:59:57 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CALwzidnYYiErH_ERYCszk6eyxcv13eV08=6PpXHDj25iSmre8Q@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <CALwzidnYYiErH_ERYCszk6eyxcv13eV08=6PpXHDj25iSmre8Q@mail.gmail.com>
Message-ID: <CAPTjJmpAkH0o=RQFTzdR+kWBBVHH8GE8P-vk76R5tdJG9gRVBw@mail.gmail.com>

On Sun, Nov 15, 2015 at 2:43 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Fri, Nov 13, 2015 at 10:40 PM, Steven D'Aprano <steve at pearwood.info> wrote:
>> Python has operator overloading, so it can be anything you want it to be.
>> E.g. you might have a DSL where +feature turns something on and -feature
>> turns it off.
>
> By that argument we should also have operators ~, !, $, \, ? because
> some hypothetical DSL might someday want to use them for something.

Unary tilde does, doing bitwise negation on integers. Backslash
probably never will, due to confusion with line continuation and
stuff. But let's look at the parallel-universe Python in which unary
plus never existed (but unary minus did). The PEP preamble for its
inclusion says:

Abstract
This PEP proposes a new unary version of the binary + operator.

Specification
A new unary operator is added to the Python language:
=======  ========================= ===========
 Op      Precedence/associativity     Method
=======  ========================= ===========
``+``    Same as unary ``-``       ``__pos__``
=======  ========================= ===========

No implementations of this methods is added to the builtin or standard
library types. However, we foresee that Domain-Specific Languages can
make use of this parallel to unary minus; see Intended usage details
below for details.


Okay. I've done my bit, stealing text from PEP 465. Now Steven, you
can write the Motivation section. There's a lot of similarities here
(Python's built-in types do not need @ or unary + for anything), but
the big push for 465 was that there have been calls for the new
operator for years. So... where would the "please add unary plus"
calls come from?

ChrisA


From rosuav at gmail.com  Sat Nov 14 12:04:18 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 04:04:18 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <87vb94ikuv.fsf@elektro.pacujo.net>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpv+tJmfav0MoVoEVhdU6y_SV2bAD0A8_2oHi6tWjnMCA@mail.gmail.com>

On Sun, Nov 15, 2015 at 3:52 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> What I don't understand is why there is a unary + but no unary /:
>
>    -x ? 0 - x
>    +x ? 0 + x
>    /x ? 1 / x
>    //x ? 1 // x
>    *x ? 1 * x
>
> You could write:
>
>    r = //(//r1 + //r2 + //r3)
>
> for
>
>    r = 1 // (1//r1 + 1//r2 + 1//r3)

Small problem: Since we have / and // operators, it's impossible to
have a unary / operator:

1 // x
1 / (/x)

But leaving that aside, the number of times you'd want this are far
fewer than the times you want unary minus.

> Actually, the real question is, is the unary - *really* so useful that
> it merits existence or is it just something that was mindlessly copied
> into programming languages from elementary school arithmetics?

More likely, copied from C. But that's why I made my other post.

ChrisA


From ian.g.kelly at gmail.com  Sat Nov 14 12:04:36 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 14 Nov 2015 10:04:36 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <87vb94ikuv.fsf@elektro.pacujo.net>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
Message-ID: <CALwzidnyzZadj5DXDgw44N9gRFQHxRfZPY67_8eJn7UEVH7WQw@mail.gmail.com>

On Nov 14, 2015 9:56 AM, "Marko Rauhamaa" <marko at pacujo.net> wrote:
>
> Ian Kelly <ian.g.kelly at gmail.com>:
>
> > For somebody reading one of these uses of unary plus in real code, I
> > imagine it would be a bit of a WTF moment if it's the first time
> > they've encountered it. I don't recall ever seeing any code that
> > actually used this, though.
>
> What I don't understand is why there is a unary + but no unary /:
>
>    -x ? 0 - x
>    +x ? 0 + x
>    /x ? 1 / x
>    //x ? 1 // x
>    *x ? 1 * x
>
> You could write:
>
>    r = //(//r1 + //r2 + //r3)
>
> for
>
>    r = 1 // (1//r1 + 1//r2 + 1//r3)

Unary integer division seems pretty silly since the only possible results
would be 0, 1 or -1.


From ian.g.kelly at gmail.com  Sat Nov 14 12:13:18 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 14 Nov 2015 10:13:18 -0700
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <CAPTjJmrCzdbcmttg+Oeb5NSXUFGeGrBifWc1+R8eL74f9baRoA@mail.gmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <CALwzidnyzZadj5DXDgw44N9gRFQHxRfZPY67_8eJn7UEVH7WQw@mail.gmail.com>
 <CAPTjJmrCzdbcmttg+Oeb5NSXUFGeGrBifWc1+R8eL74f9baRoA@mail.gmail.com>
Message-ID: <CALwzidmPA5u4y3ucb_6Bb0XUV0XXsaJHTZQWWNR4yJDGF42jSA@mail.gmail.com>

On Nov 14, 2015 10:10 AM, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Sun, Nov 15, 2015 at 4:04 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> > Unary integer division seems pretty silly since the only possible
results
> > would be 0, 1 or -1.
>
> 1, -1, or ZeroDivisionError. The zero's on the other side. But yes.

// 42 == 1 // 42 == 0


From rxjwg98 at gmail.com  Sat Nov 14 12:23:33 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 09:23:33 -0800 (PST)
Subject: What is wrong this wrapper (decorator)?
Message-ID: <dafb679e-c94c-47d2-9209-ce2a86a673d6@googlegroups.com>

Hi,

I follow a tutorial to learn decorator:

http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/

I use Enthought Canopy to run the following code.
It is really strange that the wrapper does not take effect. 
In fact, I go back to the basic way (not with @):

wrapper(sub(two, one))
Out[38]: <function checker>


When I use the non-wrapper mode, it has Coord print out.
If I use wrapper, it has nothing to print out.
Due to no debug mode help, I don't see anything wrong yet.


(add(two, one))
                                          # nothing print out
(sub(two, three))
Out[43]: Coord:-- {'y': 300, 'x': 400}    # correct is here


Anyone can help?
Thanks,



............
class Coordinate(object):
    def __init__(self, y, x):
        self.y = y
        self.x = x
    def __repr__(self):
        return "Coord:-- " + str(self.__dict__)

def add(a, b):
    return Coordinate(a.x + b.x, a.y + b.y)

def sub(a, b):
    return Coordinate(a.x - b.x, a.y - b.y)

def wrapper(func):
    def checker(a, b): # 1
        if a.x < 0 or a.y < 0:
            a = Coordinate(a.x if a.x > 0 else 0, a.y if a.y > 0 else 0)
            if b.x < 0 or b.y < 0:
                b = Coordinate(b.x if b.x > 0 else 0, b.y if b.y > 0 else 0)
            ret = func(a, b)
            if ret.x < 0 or ret.y < 0:
                ret = Coordinate(ret.x if ret.x > 0 else 0, ret.y if ret.y > 0 else 0)
            return ret
    return checker
    
one = Coordinate(100, 200)
two = Coordinate(300, 200)
three = Coordinate(-100, -100)

add = wrapper(add)
#sub = wrapper(sub)


From rxjwg98 at gmail.com  Sat Nov 14 12:29:31 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 09:29:31 -0800 (PST)
Subject: What is wrong this wrapper (decorator)?
In-Reply-To: <dafb679e-c94c-47d2-9209-ce2a86a673d6@googlegroups.com>
References: <dafb679e-c94c-47d2-9209-ce2a86a673d6@googlegroups.com>
Message-ID: <cbff0d72-c735-4a7f-8f24-a998b3c05c0e@googlegroups.com>

On Saturday, November 14, 2015 at 12:23:50 PM UTC-5, fl wrote:
> Hi,
> 
> I follow a tutorial to learn decorator:
> 
> http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/
> 
> I use Enthought Canopy to run the following code.
> It is really strange that the wrapper does not take effect. 
> In fact, I go back to the basic way (not with @):
> 
> wrapper(sub(two, one))
> Out[38]: <function checker>
> 
> 
> When I use the non-wrapper mode, it has Coord print out.
> If I use wrapper, it has nothing to print out.
> Due to no debug mode help, I don't see anything wrong yet.
> 
> 
> (add(two, one))
>                                           # nothing print out
> (sub(two, three))
> Out[43]: Coord:-- {'y': 300, 'x': 400}    # correct is here
> 
> 
> Anyone can help?
> Thanks,
> 
> 
> 
> ............
> class Coordinate(object):
>     def __init__(self, y, x):
>         self.y = y
>         self.x = x
>     def __repr__(self):
>         return "Coord:-- " + str(self.__dict__)
> 
> def add(a, b):
>     return Coordinate(a.x + b.x, a.y + b.y)
> 
> def sub(a, b):
>     return Coordinate(a.x - b.x, a.y - b.y)
> 
> def wrapper(func):
>     def checker(a, b): # 1
>         if a.x < 0 or a.y < 0:
>             a = Coordinate(a.x if a.x > 0 else 0, a.y if a.y > 0 else 0)
>             if b.x < 0 or b.y < 0:
>                 b = Coordinate(b.x if b.x > 0 else 0, b.y if b.y > 0 else 0)
>             ret = func(a, b)
>             if ret.x < 0 or ret.y < 0:
>                 ret = Coordinate(ret.x if ret.x > 0 else 0, ret.y if ret.y > 0 else 0)
>             return ret
>     return checker
>     
> one = Coordinate(100, 200)
> two = Coordinate(300, 200)
> three = Coordinate(-100, -100)
> 
> add = wrapper(add)
> #sub = wrapper(sub)

Excuse me. I just realize that the indent made the logic incorrect.
It is different from other language. Thanks.


From gengyangcai at gmail.com  Sat Nov 14 12:34:22 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 14 Nov 2015 09:34:22 -0800 (PST)
Subject: A Program that prints the numbers from 1 to 100
Message-ID: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>

I want to write a program in Python that does this ----

"Write a program that prints the numbers from 1 to 100. But for multiples of three print "Fizz" instead of the number and for the multiples of five print "Buzz". For numbers which are multiples of both three and five print "FizzBuzz"."

How do I go about doing it ?


From joel.goldstick at gmail.com  Sat Nov 14 12:49:51 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sat, 14 Nov 2015 12:49:51 -0500
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
Message-ID: <CAPM-O+yS4j=Q+ceB9GOtacBSbcrzzX+21Joib3cLinS5-8vXyw@mail.gmail.com>

On Sat, Nov 14, 2015 at 12:34 PM, Cai Gengyang <gengyangcai at gmail.com>
wrote:

> I want to write a program in Python that does this ----
>
> "Write a program that prints the numbers from 1 to 100. But for multiples
> of three print "Fizz" instead of the number and for the multiples of five
> print "Buzz". For numbers which are multiples of both three and five print
> "FizzBuzz"."
>
> How do I go about doing it ?
> --
> https://mail.python.org/mailman/listinfo/python-list
>


You could google fizzbuzz and find lots of solutions.  But, to give you a
hint, use a for loop with range to get the numbers, use if n % 3  and n % 5
to pick out 3 and 5 multiples, print accordingly
-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From bc at freeuk.com  Sat Nov 14 13:18:18 2015
From: bc at freeuk.com (BartC)
Date: Sat, 14 Nov 2015 18:18:18 +0000
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
Message-ID: <n27tp6$ec5$1@dont-email.me>

On 14/11/2015 17:34, Cai Gengyang wrote:
> I want to write a program in Python that does this ----
>
> "Write a program that prints the numbers from 1 to 100. But for multiples of three print "Fizz" instead of the number and for the multiples of five print "Buzz". For numbers which are multiples of both three and five print "FizzBuzz"."
>
> How do I go about doing it ?

Here's one way, although you're probably expected to use a loop:

print (1)
print (2)
print ("Fizz")
print (4)
print ("Buzz")
print ("Fizz")
print (7)
print (8)
print ("Fizz")
print ("Buzz")
print (11)
print ("Fizz")
print (13)
print (14)
print ("FizzBuzz")
print (16)
print (17)
print ("Fizz")
print (19)
print ("Buzz")
print ("Fizz")
print (22)
print (23)
print ("Fizz")
print ("Buzz")
print (26)
print ("Fizz")
print (28)
print (29)
print ("FizzBuzz")
print (31)
print (32)
print ("Fizz")
print (34)
print ("Buzz")
print ("Fizz")
print (37)
print (38)
print ("Fizz")
print ("Buzz")
print (41)
print ("Fizz")
print (43)
print (44)
print ("FizzBuzz")
print (46)
print (47)
print ("Fizz")
print (49)
print ("Buzz")
print ("Fizz")
print (52)
print (53)
print ("Fizz")
print ("Buzz")
print (56)
print ("Fizz")
print (58)
print (59)
print ("FizzBuzz")
print (61)
print (62)
print ("Fizz")
print (64)
print ("Buzz")
print ("Fizz")
print (67)
print (68)
print ("Fizz")
print ("Buzz")
print (71)
print ("Fizz")
print (73)
print (74)
print ("FizzBuzz")
print (76)
print (77)
print ("Fizz")
print (79)
print ("Buzz")
print ("Fizz")
print (82)
print (83)
print ("Fizz")
print ("Buzz")
print (86)
print ("Fizz")
print (88)
print (89)
print ("FizzBuzz")
print (91)
print (92)
print ("Fizz")
print (94)
print ("Buzz")
print ("Fizz")
print (97)
print (98)
print ("Fizz")
print ("Buzz")

-- 
Bartc




From breamoreboy at yahoo.co.uk  Sat Nov 14 13:25:04 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Sat, 14 Nov 2015 18:25:04 +0000
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
Message-ID: <n27uaf$tkp$1@ger.gmane.org>

On 14/11/2015 17:34, Cai Gengyang wrote:
> I want to write a program in Python that does this ----
>
> "Write a program that prints the numbers from 1 to 100. But for multiples of three print "Fizz" instead of the number and for the multiples of five print "Buzz". For numbers which are multiples of both three and five print "FizzBuzz"."
>
> How do I go about doing it ?
>

This homework problem has been asked repeatedly over the years.  Just 
use your favourite search engine and there will be numerous answers. 
However if you actually want to learn you'll have to try writing your 
own code at some point, so see 
https://docs.python.org/3/library/functions.html#func-range and 
https://docs.python.org/3/library/stdtypes.html#index-14 operation "x % y".

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From rxjwg98 at gmail.com  Sat Nov 14 15:00:22 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 12:00:22 -0800 (PST)
Subject: What is the right way to import a package?
Message-ID: <8e325d88-6ad1-46e3-a1fb-ef8c28dc50a8@googlegroups.com>

Hi,

I want to use a code snippet found on-line. It has such content:

from numpy import *
dt = 0.1
# Initialization of state matrices
X = array([[0.0], [0.0], [0.1], [0.1]])

# Measurement matrices
Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])



When the above content is inside a .py document and running, there will be
 an error:

---> 15 Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
     16 #Y = ([[X[0,0]], [X[1,0] + 0]])

NameError: name 'randn' is not defined 


But when I run the above line by line at the console (Canopy), there will be
no error for the above line.

My question is: 

The import and the following are wrong. 

X = array([[0.0], [0.0], [0.1], [0.1]])

It should be:

import numpy as np
...
Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])

This looks like the code I once saw. But the file when running has such
 error:

---> 15 Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])

AttributeError: 'module' object has no attribute 'randn'

When it is run line by line at the console, it has the same error.

It is strange that the same content has errors depends on inside a file, or
at CLI console.

What is missing I don't realize? Thanks,




From marko at pacujo.net  Sat Nov 14 16:53:36 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 14 Nov 2015 23:53:36 +0200
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.334.1447520685.16136.python-list@python.org>
Message-ID: <87a8qgi6xr.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> On Nov 14, 2015 9:56 AM, "Marko Rauhamaa" <marko at pacujo.net> wrote:
>>    r = //(//r1 + //r2 + //r3)
>
> Unary integer division seems pretty silly since the only possible
> results would be 0, 1 or -1.

Yep, mixed them up.


Marko


From auriocus at gmx.de  Sat Nov 14 16:59:11 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 14 Nov 2015 22:59:11 +0100
Subject: What is the right way to import a package?
In-Reply-To: <8e325d88-6ad1-46e3-a1fb-ef8c28dc50a8@googlegroups.com>
References: <8e325d88-6ad1-46e3-a1fb-ef8c28dc50a8@googlegroups.com>
Message-ID: <n28an5$2f8$1@dont-email.me>

Am 14.11.15 um 21:00 schrieb fl:
> from numpy import *
> dt = 0.1
> # Initialization of state matrices
> X = array([[0.0], [0.0], [0.1], [0.1]])
>
> # Measurement matrices
> Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
>
> When the above content is inside a .py document and running, there will be
>   an error:
>
> ---> 15 Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
>       16 #Y = ([[X[0,0]], [X[1,0] + 0]])
>
> NameError: name 'randn' is not defined
>
> But when I run the above line by line at the console (Canopy), there will be
> no error for the above line.

Maybe Canopy is doing a

	from pylab import *

for you?

	Christian



From random832 at fastmail.com  Sat Nov 14 17:53:54 2015
From: random832 at fastmail.com (Random832)
Date: Sat, 14 Nov 2015 17:53:54 -0500
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
Message-ID: <m27flkqjjx.fsf@fastmail.com>

Marko Rauhamaa <marko at pacujo.net> writes:
> Actually, the real question is, is the unary - *really* so useful that
> it merits existence or is it just something that was mindlessly copied
> into programming languages from elementary school arithmetics?

The alternative, if you want to be able to specify negative numbers at
all, is to put - in the literal syntax. So what's "x-1"?

I suppose you could use some *different* symbol in the literal syntax
for negative numbers. I had a calculator once that used a different
symbol (looked like a small superscript minus sign) for it. But Python
is limited to ASCII for basic syntax elements for good reasons.



From marko at pacujo.net  Sat Nov 14 19:12:28 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 15 Nov 2015 02:12:28 +0200
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.338.1447541659.16136.python-list@python.org>
Message-ID: <876114i0ib.fsf@elektro.pacujo.net>

Random832 <random832 at fastmail.com>:

> Marko Rauhamaa <marko at pacujo.net> writes:
>> Actually, the real question is, is the unary - *really* so useful
>> that it merits existence or is it just something that was mindlessly
>> copied into programming languages from elementary school arithmetics?
>
> The alternative, if you want to be able to specify negative numbers at
> all, is to put - in the literal syntax. So what's "x-1"?

Yes, it would have to be part of the literal syntax.

Or, you could do without!

   >>> 7 - 8
   (0-1)

After all, we already have:

   >>> 1 + 3j
   (1+3j)


Marko


From vjp2.at at at.BioStrategist.dot.dot.com  Sat Nov 14 19:35:49 2015
From: vjp2.at at at.BioStrategist.dot.dot.com (vjp2.at at at.BioStrategist.dot.dot.com)
Date: Sun, 15 Nov 2015 00:35:49 +0000 (UTC)
Subject: Jython standalone
References: <n26349$hin$3@reader1.panix.com>
 <56469dee$0$1612$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n28k15$38c$1@reader1.panix.com>


Jython is python in java at jython.org. 

I tried clicking and double clicking.

I does a wait cycle (rotating arrow) 
then returns to attention.

I'm trying to run RDKIT, an app written for jython.
THen I realised jython wasn't working at all.

I've had same problem with some java jars. 
I only keep java jars that respond.
If they don't respond, I assume they don't work.
But now I'm wondering.

				    - = -
 Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
		    http://www.panix.com/~vjp2/vasos.htm
  ---{Nothing herein constitutes advice.  Everything fully disclaimed.}---
   [Homeland Security means private firearms not lazy obstructive guards]
 [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]






From python at mrabarnett.plus.com  Sat Nov 14 19:49:33 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 15 Nov 2015 00:49:33 +0000
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <m27flkqjjx.fsf@fastmail.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net> <m27flkqjjx.fsf@fastmail.com>
Message-ID: <5647D69D.4070406@mrabarnett.plus.com>

On 2015-11-14 22:53, Random832 wrote:
> Marko Rauhamaa <marko at pacujo.net> writes:
>> Actually, the real question is, is the unary - *really* so useful that
>> it merits existence or is it just something that was mindlessly copied
>> into programming languages from elementary school arithmetics?
>
> The alternative, if you want to be able to specify negative numbers at
> all, is to put - in the literal syntax. So what's "x-1"?
>
> I suppose you could use some *different* symbol in the literal syntax
> for negative numbers. I had a calculator once that used a different
> symbol (looked like a small superscript minus sign) for it. But Python
> is limited to ASCII for basic syntax elements for good reasons.
>
APL uses "?" ('\N{MACRON}'), e.g. "?1".



From james at imagewebdesign.co.uk  Sat Nov 14 20:00:59 2015
From: james at imagewebdesign.co.uk (james at imagewebdesign.co.uk)
Date: Sat, 14 Nov 2015 17:00:59 -0800 (PST)
Subject: pygtk beginner script not working
Message-ID: <5b6f7b3f-a132-4305-8ab7-a256b9dbf40f@googlegroups.com>

Hi guys

I'm new to Python so please bare with me :)

I'm using python 2.7.10 as advised (more tools apparently over 3.x)

Trying to use this script

[CODE]
#!/usr/bin/env python

# example base.py

import pygtk

pygtk.require('2.0')
import gtk

class Base:
   def __init__(self):
      self.window = gtk.Window(gtk.WINDOW_TOPLEVEL)
      self.window.show()

def main(self):
   gtk.main()
   
   print __name__
   if __name__ == "__main__":
      base = Base()
      base.main()
[/CODE]

But get this error:

[i]File "C:\Users\CMDEV\Desktop\Py\pygtk_1.py", line 5, in <module>
    import pygtk
ImportError: No module named pygtk[/i]

I've check the install and everything reports its installed right:

Here's a grab of the CLI


[CODE]
C:\Python27>easy_install -U pygtk
Searching for pygtk
Reading https://pypi.python.org/simple/pygtk/
Reading http://ftp.acc.umu.se/pub/gnome/binaries/win32/pygtk/2.24/
Reading http://www.daa.com.au/~james/pygtk/
Reading http://www.daa.com.au/~james/software/pygtk/
Reading http://www.pygtk.org
Reading http://www.pygtk.org/
Best match: pygtk 2.24.0
Processing pygtk-2.24.0-py2.7-win32.egg
pygtk 2.24.0 is already the active version in easy-install.pth
Installing pygtk_postinstall.py script to C:\Python27\Scripts
Installing pygtk_postinstall.pyc script to C:\Python27\Scripts

Using c:\python27\lib\site-packages\pygtk-2.24.0-py2.7-win32.egg
Processing dependencies for pygtk
Finished processing dependencies for pygtk

C:\Python27>python C:\Users\CMDEV\Desktop\Py\pygtk_1.py
Traceback (most recent call last):
  File "C:\Users\CMDEV\Desktop\Py\pygtk_1.py", line 5, in <module>
    import pygtk
ImportError: No module named pygtk
[/CODE]


(not used google groups before to post on so not sure if BB code works here... also there doesn't seem to be a preview button so no idea how this turns out)

Cheers


From steve at pearwood.info  Sat Nov 14 20:14:45 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 15 Nov 2015 12:14:45 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.338.1447541659.16136.python-list@python.org>
Message-ID: <5647dc88$0$1592$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 09:53 am, Random832 wrote:

> Marko Rauhamaa <marko at pacujo.net> writes:
>> Actually, the real question is, is the unary - *really* so useful that
>> it merits existence or is it just something that was mindlessly copied
>> into programming languages from elementary school arithmetics?
> 
> The alternative, if you want to be able to specify negative numbers at
> all, is to put - in the literal syntax. So what's "x-1"?
> 
> I suppose you could use some *different* symbol in the literal syntax
> for negative numbers. I had a calculator once that used a different
> symbol (looked like a small superscript minus sign) for it. But Python
> is limited to ASCII for basic syntax elements for good reasons.

I have a textbook for Pascal programming which includes a project to write
an "arithmetic evaluator". It uses ~ for unary minus and - for binary
subtraction, and doesn't include unary plus. The reason was to simplify the
parser, so that every symbol had exactly one meaning.

So in an alternate universe where Guido was less influenced by C, or where
he wasn't as good as writing parsers as the real GvR is, we may have ended
up with ~ for unary minus and no unary plus.



-- 
Steven



From steve at pearwood.info  Sat Nov 14 20:34:46 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 15 Nov 2015 12:34:46 +1100
Subject: Jython standalone
References: <n26349$hin$3@reader1.panix.com>
 <56469dee$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <n28k15$38c$1@reader1.panix.com>
Message-ID: <5647e139$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 11:35 am, vjp2.at at at.BioStrategist.dot.dot.com wrote:

> Jython is python in java at jython.org.
> 
> I tried clicking and double clicking.

Hi Vanos,

I am perfectly aware of what Jython is, what I don't know is what you
are "clicking and double-clicking".

While we are very smart and will surely be able to help you, we are not
mind-readers, and we cannot see what is on your computer. You have to help
us to help you.

That means you have to be *precise and exact* about what you are doing, not
vague. I asked you a set of questions, and you have ignored every single
one of them. How do you expect us to know what you are doing? We do not
have a magic crystal ball.


> I does a wait cycle (rotating arrow)
> then returns to attention.

I am going to GUESS that you are trying to run the Jython installer that you
got from here:

http://www.jython.org/downloads.html

My GUESS is that you have downloaded the installer to your desktop.

Since you haven't told me what operating system you are using, I am going to
GUESS that you are using Linux, since that is what I am most familiar with.

I assume you are using a desktop manager, right-click on the desktop
background and select the command to open a terminal or console. In TDE or
KDE 3, that will probably be called "Konsole". Or use the Start menu to
open a terminal, the menu could be:

Start > System > Terminal

or 

Start > Accessories > Terminal

or similar, depending on which desktop manager you are using. (If you are
using Windows or OS X, there will be some other way to get a terminal or
console, but I don't now it.)

At the terminal window, you should see a prompt that looks like $ (dollar
sign). At the prompt, type:

cd ~/Desktop

and then press the Enter key. The space between "cd" and the tilde ~ is
important. Now type:

java -jar jython_installer-2.7.0.jar

and press Enter. Again, spaces between words are important.

If everything works correctly, the Jython installer GUI will run, and you
can install Jython.

But if the installer doesn't run, you will probably get a bunch of error
messages printed to the terminal window. COPY and PASTE those error
messages, and send them to us here. Don't re-type them, and don't try to
summarise. We need to see the EXACT messages.



-- 
Steven



From steve at pearwood.info  Sat Nov 14 20:39:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 15 Nov 2015 12:39:20 +1100
Subject: A Program that prints the numbers from 1 to 100
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
Message-ID: <5647e24a$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 04:34 am, Cai Gengyang wrote:

> I want to write a program in Python that does this ----
> 
> "Write a program that prints the numbers from 1 to 100. But for multiples
> of three print "Fizz" instead of the number and for the multiples of five
> print "Buzz". For numbers which are multiples of both three and five print
> "FizzBuzz"."
> 
> How do I go about doing it ?

Start by writing a program that prints the numbers from 1 to 100. Hint:

# Program to print the numbers from 1 to 10.
for i in range(1, 11):
    print(i)


One you get that far, you will need to decide which numbers are multiples of
3, which are multiples of 5, and which are multiples of both 3 and 5. Hint:

# Multiples of 7.
for i in range(1, 11):
    print(i)
    if i % 7 == 0:
        print("multiple of seven")


If you need more help, show us the code you have written.



-- 
Steven



From rxjwg98 at gmail.com  Sat Nov 14 20:54:48 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 17:54:48 -0800 (PST)
Subject: What meaning is of '#!python'?
Message-ID: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>

Hi,

I see an example Python code has such a line at the file beginning:

#!python


Is there some meaning about it?

Thanks,


From rosuav at gmail.com  Sat Nov 14 20:58:39 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 12:58:39 +1100
Subject: What meaning is of '#!python'?
In-Reply-To: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
Message-ID: <CAPTjJmoNjpFKUgfOiejtLTjLK+yqx-MAtdGzEj4QNxcuxq4T4Q@mail.gmail.com>

On Sun, Nov 15, 2015 at 12:54 PM, fl <rxjwg98 at gmail.com> wrote:
> I see an example Python code has such a line at the file beginning:
>
> #!python
>
>
> Is there some meaning about it?

It probably didn't look exactly like that. Please, when you're asking
questions, COPY AND PASTE rather than retyping some approximation of
what you saw.

As it happens, I can tell what you're asking about - it's called a
shebang - but I very much doubt that it was exactly what you wrote.

ChrisA


From steve at pearwood.info  Sat Nov 14 21:08:11 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 15 Nov 2015 13:08:11 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
Message-ID: <5647e90c$0$1588$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 02:43 am, Ian Kelly wrote:

> On Fri, Nov 13, 2015 at 10:40 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> Python has operator overloading, so it can be anything you want it to be.
>> E.g. you might have a DSL where +feature turns something on and -feature
>> turns it off.
> 
> By that argument we should also have operators ~, !, $, \, ? because
> some hypothetical DSL might someday want to use them for something.

No, I'm not saying that. I'm saying that since Python *already* has unary
plus, it can be overloaded to do anything you want. I'm not saying that
hypothetical DSLs are a good reason to add a bunch of arbitrary new
do-nothing-by-default operators.

(By the way, Python already has the ~ bitwise not operator.)


>> Decimal uses it to force the current precision and rounding, regardless
>> of what the number was initiated to:
>>
>> Counter uses it to strip zero and negative counts:
>>
>> I would expect that symbolic maths software like Sympy probably has use
>> of a unary plus operator, but I'm not sure.
> 
> Unary plus as normalization does not strike me as being very
> intuitive. 

Well, in truth the only truly intuitive interface is the nipple, but using +
for normalisation works for me. It's no more weird than ** for raising to
the power, % for remainder after division, or != for not equal.


>> I might consider stealing an idea from Perl and Javascript, and have
>> unary plus convert strings to a number:
>>
>> +"123"
>> => returns int 123
>> +"1.23"
>> => returns float 1.23
> 
> Eww.

Well of course it's "eww" when you write it as a literal, but you wouldn't
do that except to illustrate the concept, that's just silly. But compare:

number = +raw_input("enter a number: ")

versus:

text = raw_input("enter a number: ")
try:
    number = float(text)
except ValueError: 
    number = int(text)


Or worse, people who don't think of try...except will probably try parsing
the string by hand. 

text = raw_input("enter a number: ").strip()
if text.isdigit() or text.startswith("-") and text[1:].isdigit():
    number = int(text)
else:
    # Floats are allowed a leading - or +, no more than one decimal point,
    # no more than one exponent starting with E or e, and an optional
    # leading + or -  sign in the exponent. Everything else must be digits.
    mantissa, exponent = number.upper().split("E", 1)
    ...

And that's about the point where I stopped because correctly parsing floats
by hand is complicated. But the point is that there was a time in my life
as a Python programmer where I absolutely would have done that, rather than
thinking of try...except.


-- 
Steven



From rxjwg98 at gmail.com  Sat Nov 14 21:13:04 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 18:13:04 -0800 (PST)
Subject: What meaning is of '#!python'?
In-Reply-To: <mailman.340.1447552722.16136.python-list@python.org>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <mailman.340.1447552722.16136.python-list@python.org>
Message-ID: <3aa2f352-ea19-4252-9a09-c884887cf810@googlegroups.com>

On Saturday, November 14, 2015 at 8:58:57 PM UTC-5, Chris Angelico wrote:
> On Sun, Nov 15, 2015 at 12:54 PM, fl <gmail.com> wrote:
> > I see an example Python code has such a line at the file beginning:
> >
> > #!python
> >
> >
> > Is there some meaning about it?
> 
> It probably didn't look exactly like that. Please, when you're asking
> questions, COPY AND PASTE rather than retyping some approximation of
> what you saw.
> 
> As it happens, I can tell what you're asking about - it's called a
> shebang - but I very much doubt that it was exactly what you wrote.
> 
> ChrisA

Excuse me. Below is copied from the .py file:

#!python
from numpy import *
from numpy.random import *


def resample(weights):
  n = len(weights)
  indices = []


Thanks,


From rosuav at gmail.com  Sat Nov 14 21:18:30 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 13:18:30 +1100
Subject: What meaning is of '#!python'?
In-Reply-To: <3aa2f352-ea19-4252-9a09-c884887cf810@googlegroups.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <mailman.340.1447552722.16136.python-list@python.org>
 <3aa2f352-ea19-4252-9a09-c884887cf810@googlegroups.com>
Message-ID: <CAPTjJmqs7yEeana50mH0PxayiUwsSBXeye2_gKcEFbUkbVQeWQ@mail.gmail.com>

On Sun, Nov 15, 2015 at 1:13 PM, fl <rxjwg98 at gmail.com> wrote:
> Excuse me. Below is copied from the .py file:
>
> #!python
> from numpy import *
> from numpy.random import *
>

Then someone doesn't know how to use a shebang (or is deliberately
abusing it), and you can ignore it. It starts with a hash, ergo it's a
comment.

ChrisA


From rxjwg98 at gmail.com  Sat Nov 14 21:23:53 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 18:23:53 -0800 (PST)
Subject: What function is 'u0, j = random(), 0'?
Message-ID: <f2965552-575a-44fc-9c34-dbc4792d4208@googlegroups.com>

Hi,

When I read the below code, I cannot make the last line (with ######) out.



def res(weights):
  n = len(weights)
  indices = []
  C = [0.] + [sum(weights[:i+1]) for i in range(n)]
  u0, j = random(), 0  ######


If I run below code on console, it will say an error.

uu, 0.1, 0


What difference is between these two example lines?

Thanks,


From rosuav at gmail.com  Sat Nov 14 21:23:59 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 13:23:59 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <5647e90c$0$1588$c3e8da3$5496439d@news.astraweb.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <5647e90c$0$1588$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmos8krz-wvydtnsTboM5LDmQg3oTKQmh-5JR=cP8neqbg@mail.gmail.com>

On Sun, Nov 15, 2015 at 1:08 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> number = +raw_input("enter a number: ")
>
> versus:
>
> text = raw_input("enter a number: ")
> try:
>     number = float(text)
> except ValueError:
>     number = int(text)

What kinds of strings can float() not handle but int() can, and in a
program that's going to group floats and ints together as "numbers",
will they ever be useful? I'd be more likely to write this as simply:

number = float(input("Enter a number: "))

(Also, I use Python 3. No raw. But same diff.)

ChrisA


From zachary.ware+pylist at gmail.com  Sat Nov 14 21:26:50 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Sat, 14 Nov 2015 20:26:50 -0600
Subject: What meaning is of '#!python'?
In-Reply-To: <CAPTjJmoNjpFKUgfOiejtLTjLK+yqx-MAtdGzEj4QNxcuxq4T4Q@mail.gmail.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <CAPTjJmoNjpFKUgfOiejtLTjLK+yqx-MAtdGzEj4QNxcuxq4T4Q@mail.gmail.com>
Message-ID: <CAKJDb-OtX5giW9KRSTo5F1GDp=uLHsK3qaT0p=k5yrxj7met4g@mail.gmail.com>

On Sat, Nov 14, 2015 at 7:58 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Sun, Nov 15, 2015 at 12:54 PM, fl <rxjwg98 at gmail.com> wrote:
>> I see an example Python code has such a line at the file beginning:
>>
>> #!python
>>
>>
>> Is there some meaning about it?
>
> It probably didn't look exactly like that. Please, when you're asking
> questions, COPY AND PASTE rather than retyping some approximation of
> what you saw.

"#!python" is a valid shebang for the Python Launcher for Windows.
It's also a not-too-terrible placeholder for a Unix shebang meaning
"whichever Python you want it to be".  The better choice for use with
both platforms would be "#!/usr/bin/env python", though.

-- 
Zach


From torriem at gmail.com  Sat Nov 14 21:28:19 2015
From: torriem at gmail.com (Michael Torrie)
Date: Sat, 14 Nov 2015 19:28:19 -0700
Subject: What meaning is of '#!python'?
In-Reply-To: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
Message-ID: <5647EDC3.1030606@gmail.com>

On 11/14/2015 06:54 PM, fl wrote:
> Hi,
> 
> I see an example Python code has such a line at the file beginning:
> 
> #!python
> 
> 
> Is there some meaning about it?

Supposed to be, yes, but the line you've pasted there wouldn't work on
any system I know of.

https://en.wikipedia.org/wiki/Shebang_%28Unix%29



From rxjwg98 at gmail.com  Sat Nov 14 21:37:33 2015
From: rxjwg98 at gmail.com (fl)
Date: Sat, 14 Nov 2015 18:37:33 -0800 (PST)
Subject: Question about yield
Message-ID: <ac359441-8cca-496c-b5c2-d3e7d7ce15dd@googlegroups.com>

Hi,
I have read a couple of tutorial on yield. The following code snippet still
gives me a shock. I am told yield is a little like return. I only see one 
yield in the tutorial examples. Here it has two yields. And there are three
variables following keyword yield.
I have not tried debug function to get the running states yet.
Could you give me some explanation on this yield usage?
Or are there some high relevant tutorial on this?

Thanks, 



def pfr(sequence, pos, stepsize, n):
  seq = iter(sequence)
  x = ones((n, 2), int) * pos                   # position
  f0 = seq.next()[tuple(pos)] * ones(n)         # model
  yield pos, x, ones(n)/n                       # weights
  for im in seq:
    x += uniform(-stepsize, stepsize, x.shape)  # 
    x  = x.clip(zeros(2), array(im.shape)-1).astype(int) # 
    f  = im[tuple(x.T)]                         # s
    w  = 1./(1. + (f0-f)**2)                    # distance
    w /= sum(w)                                 # w
    yield sum(x.T*w, axis=1), x, w              # weights
    if 1./sum(w**2) < n/2.:                     # degenerate:
      x  = x[res(w),:]                     # to weights


From rosuav at gmail.com  Sat Nov 14 21:43:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 15 Nov 2015 13:43:41 +1100
Subject: Question about yield
In-Reply-To: <ac359441-8cca-496c-b5c2-d3e7d7ce15dd@googlegroups.com>
References: <ac359441-8cca-496c-b5c2-d3e7d7ce15dd@googlegroups.com>
Message-ID: <CAPTjJmomNnKL5k4yz7+ZnP964Gw9i8=m5COJ1D7KEqs+=_fitA@mail.gmail.com>

On Sun, Nov 15, 2015 at 1:37 PM, fl <rxjwg98 at gmail.com> wrote:
> Or are there some high relevant tutorial on this?
>

Start here:

https://docs.python.org/3/tutorial/index.html

ChrisA


From zachary.ware+pylist at gmail.com  Sat Nov 14 21:47:15 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Sat, 14 Nov 2015 20:47:15 -0600
Subject: What function is 'u0, j = random(), 0'?
In-Reply-To: <f2965552-575a-44fc-9c34-dbc4792d4208@googlegroups.com>
References: <f2965552-575a-44fc-9c34-dbc4792d4208@googlegroups.com>
Message-ID: <CAKJDb-N64iSTiCDkxfOgxO9Q71OYB4YNJaxP17-414o8hjWA7w@mail.gmail.com>

Hi,

On Sat, Nov 14, 2015 at 8:23 PM, fl <rxjwg98 at gmail.com> wrote:
> Hi,
>
> When I read the below code, I cannot make the last line (with ######) out.
>
>
>
> def res(weights):
>   n = len(weights)
>   indices = []
>   C = [0.] + [sum(weights[:i+1]) for i in range(n)]
>   u0, j = random(), 0  ######
>
>
> If I run below code on console, it will say an error.
>
> uu, 0.1, 0
>
>
> What difference is between these two example lines?

I've noticed you sending a lot of questions in the past day or two,
many at a fairly basic level.  I think you would be well-served to
read through the tutorial at https://docs.python.org/3/tutorial.  It's
been a while since I last read it, but I believe this question is
covered there.

To give to an answer anyway, the two lines ("u0, j = random(), 0" and
"uu, 0.1, 0") are very different.

The first is a tuple unpacking assignment.  The right side (everything
right of the equal sign) creates a tuple (comma creates a tuple, not
parentheses) of the result of calling the 'random', and 0. The left
side the equal sign is a list of names to which the right side values
are assigned; the result of random() is assigned to the name 'u0', and
0 is assigned to 'j'.  The same result could be achieved by the
following two lines:

   u0 = random()
   j = 0

The second line attempts to make a tuple out of the value assigned to
the name 'uu', the float 0.1, and the int 0, and throw it away.  I'm
assuming the error you got was a NameError because nothing was
assigned to 'uu', but I could be wrong.  For future questions, you
should copy and paste the full traceback, which gives *a lot* more
information than "there was an error".

Hope this helps,
-- 
Zach


From ben+python at benfinney.id.au  Sat Nov 14 22:03:46 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sun, 15 Nov 2015 14:03:46 +1100
Subject: Learning Python from the tutorial (was: What function is 'u0,
 j = random(), 0'?)
References: <f2965552-575a-44fc-9c34-dbc4792d4208@googlegroups.com>
 <CAKJDb-N64iSTiCDkxfOgxO9Q71OYB4YNJaxP17-414o8hjWA7w@mail.gmail.com>
Message-ID: <854mgodkvh.fsf_-_@benfinney.id.au>

Zachary Ware <zachary.ware+pylist at gmail.com> writes:

> I've noticed you sending a lot of questions in the past day or two,
> many at a fairly basic level.  I think you would be well-served to
> read through the tutorial at https://docs.python.org/3/tutorial.

Better than merely reading through it: Anyone who wants to learn Python
from the official tutorial should *work through* the tutorial. Run each
example, read the tutorial to get an explanation, experiment to test
whether you understand. Only then, continue on.

-- 
 \       ?I bought some powdered water, but I don't know what to add.? |
  `\                                                    ?Steven Wright |
_o__)                                                                  |
Ben Finney



From rhills at medimorphosis.com.au  Sat Nov 14 22:10:54 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Sun, 15 Nov 2015 11:10:54 +0800
Subject: What meaning is of '#!python'?
In-Reply-To: <CAPTjJmqs7yEeana50mH0PxayiUwsSBXeye2_gKcEFbUkbVQeWQ@mail.gmail.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <mailman.340.1447552722.16136.python-list@python.org>
 <3aa2f352-ea19-4252-9a09-c884887cf810@googlegroups.com>
 <CAPTjJmqs7yEeana50mH0PxayiUwsSBXeye2_gKcEFbUkbVQeWQ@mail.gmail.com>
Message-ID: <5647F7BE.902@medimorphosis.com.au>

On 15/11/15 10:18, Chris Angelico wrote:
> On Sun, Nov 15, 2015 at 1:13 PM, fl <rxjwg98 at gmail.com> wrote:
>> Excuse me. Below is copied from the .py file:
>>
>> #!python
>> from numpy import *
>> from numpy.random import *
>>
> Then someone doesn't know how to use a shebang (or is deliberately
> abusing it), and you can ignore it. It starts with a hash, ergo it's a
> comment.
>
> ChrisA

Looks like the author of the script file has tried to create a Python
Shell script.  This link describes them in detail:

http://www.dreamsyssoft.com/python-scripting-tutorial/intro-tutorial.php

Not sure whether the example originally quoted would work, I imagine it
might on some 'nix operating systems.

The more common first line is:

    #!/usr/bin/env python

If you start a script file with this line and make the file executable,
you can then run the script from the command line without having to
preface it with a reference to your Python executable.  Eg:

    my-script.py


versus

    python my-script.py


HTH,

-- 
Rob Hills
Waikiki, Western Australia



From eryksun at gmail.com  Sun Nov 15 00:57:47 2015
From: eryksun at gmail.com (eryksun)
Date: Sat, 14 Nov 2015 23:57:47 -0600
Subject: What meaning is of '#!python'?
In-Reply-To: <CAKJDb-OtX5giW9KRSTo5F1GDp=uLHsK3qaT0p=k5yrxj7met4g@mail.gmail.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <CAPTjJmoNjpFKUgfOiejtLTjLK+yqx-MAtdGzEj4QNxcuxq4T4Q@mail.gmail.com>
 <CAKJDb-OtX5giW9KRSTo5F1GDp=uLHsK3qaT0p=k5yrxj7met4g@mail.gmail.com>
Message-ID: <CACL+1at=zb12B=Ji4Y_n=QygwFs7UDKxVrQ=iNvtSonzuAzgxA@mail.gmail.com>

On Sat, Nov 14, 2015 at 8:26 PM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
>
> "#!python" is a valid shebang for the Python Launcher for Windows.
> It's also a not-too-terrible placeholder for a Unix shebang meaning
> "whichever Python you want it to be".  The better choice for use with
> both platforms would be "#!/usr/bin/env python", though.

The "/usr/bin/env python" virtual command searches the directories in
PATH, trying each file extension from PATHEXT such as "python.COM",
"python.EXE", and so on. You can also search for other programs such
as "pypy". Note that qualifying "python" (but not other names) as
"python2" or "python3.5" makes the launcher use the registry instead
of searching PATH.

"#!/usr/bin/python" may be better in some cases. This defaults to the
latest installed version of 2.x (or 3.x if no 2.x is installed) that's
configured in the Windows registry. Or specify "python2" or "python3"
to use the latest 2.x or 3.x. These commands can be configured to use
a particular major[.minor[-32]] version via the environment variables
PY_PYTHON, PY_PYTHON2, and PY_PYTHON3. Or you can configure them
instead by setting the "python", "python2" and "python3" keys in the
[defaults] section of the configuration file "%LOCALAPPDATA%\py.ini".
Note that the environment variable overrides the corresponding py.ini
key.

When portability isn't a concern you can use a Windows path in the
shebang such as "#!C:\pypy40\pypy.exe".

https://docs.python.org/3/using/windows.html#shebang-lines


From auriocus at gmx.de  Sun Nov 15 03:33:40 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sun, 15 Nov 2015 09:33:40 +0100
Subject: Jython standalone
In-Reply-To: <n28k15$38c$1@reader1.panix.com>
References: <n26349$hin$3@reader1.panix.com>
 <56469dee$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <n28k15$38c$1@reader1.panix.com>
Message-ID: <n29fsp$p1b$1@dont-email.me>

Am 15.11.15 um 01:35 schrieb vjp2.at at at.BioStrategist.dot.dot.com:
> Jython is python in java at jython.org.
>
> I tried clicking and double clicking.
>
> I does a wait cycle (rotating arrow)
> then returns to attention.

I think you are describing the Windows mouse cursor that displays a 
rotating wheel to indicate "busy". Aren't you?

 From looking at the jython website, it states:

Download Jython 2.7.0 - Standalone Jar : For embedding Jython in Java 
applications

"embedding Jython in Java applications" means, that you can integrate it 
into a Java program that you are writing. You will not be able to double 
click and run this jar; it is a library, not an application.

Try the installer instead.

	Christian


From lokotraktor at email.cz  Sun Nov 15 04:19:07 2015
From: lokotraktor at email.cz (lokotraktor at email.cz)
Date: Sun, 15 Nov 2015 10:19:07 +0100 (CET)
Subject: WinXP invalid python 3.5 installation
Message-ID: <XN9.1RFom.6lbrKHvhi4s.1MI4uB@seznam.cz>

Dear all,

Would you be so kind and help me to find a fix of my trouble?

I have had installed python 2.7 already.
I have downloaded the
https://www.python.org/ftp/python/3.5.0/python-3.5.0.exe
and have installed it on Windows XP Home Edition Version 2002 SP3 (I am the 
administrator, which is on czech laguage the word "Spravce".)

Please see kindly attachements:
python_3,5_empty_installer_window.png
.. First I saw the incomplete python installer window. Clicking just in the 
"empty middle" the installation process of the Python 3.5.0 started and 
succesfully (?)? finished.

Trying to launche the newly installed python I encounter troubles depicted 
at:
python_3,5_not_valid_app_of_win32_type.png .. python.exe is not valid 
application of Win32 type.
python_3,5_not_valid_app_of_win32_type_2.png .. (The "Pristup byl odepren." 
means Acces denied.)

After a little bit googling I have find depends.exe to get know the python 
installation was complete or not.
The finding of depends is not good. See kindly the
python_3,5_depends_s_finding.png

Finaly I tried to uninstall python 3.5. using Control panels, Add or Remove 
Programs, Python, Uninstall (everything on czech language so that I do not 
know propper english wnidows terms). As I see the "incomplete python 
installer window" I tried to click in the middle of empty area. Another fail
appeared to me:
python_3.5_unable_to_remove.png
python-unistal-log.txt

Is something I can fix to obtain fully working upgrade of Python 3.5 on my 
Windows XP?
Please, feel free to ask me for more detailled information.
Best regards,
Jiri Fajmon
-------------- next part --------------
?[17C0:17D4][2015-11-15T10:07:17]i001: Burn v3.10.0.1823, Windows v5.1 (Build 2600: Service Pack 3), path: C:\Documents and Settings\Spravce\Local Settings\Data aplikac?\Package Cache\{1197d2bb-6cf8-488a-b994-d5bf6d7efe7b}\python-3.5.0.exe
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'ActionLikeInstalling' to value 'Installing'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'ActionLikeInstallation' to value 'Setup'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'ShortVersion' to value '3.5'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'ShortVersionNoDot' to value '35'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'InstallAllUsers' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'InstallLauncherAllUsers' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'TargetDir' to value ''
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'DefaultAllUsersTargetDir' to value '[ProgramFilesFolder]Python [ShortVersion]'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'TargetPlatform' to value 'x86'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'DefaultJustForMeTargetDir' to value '[LocalAppDataFolder]Programs\Python\Python[ShortVersionNoDot]-32'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'OptionalFeaturesRegistryKey' to value 'Software\Python\PythonCore\[ShortVersion]-32\InstalledFeatures'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'TargetDirRegistryKey' to value 'Software\Python\PythonCore\[ShortVersion]-32\InstallPath'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'DefaultCustomTargetDir' to value ''
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'InstallAllUsersState' to value 'enabled'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'InstallLauncherAllUsersState' to value 'enabled'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'CustomInstallLauncherAllUsersState' to value '[InstallLauncherAllUsersState]'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'TargetDirState' to value 'enabled'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'CustomBrowseButtonState' to value 'enabled'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_core' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_exe' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_dev' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_lib' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_test' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_doc' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_tools' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_tcltk' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_pip' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_launcher' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_symbols' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Include_debug' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'LauncherOnly' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'AssociateFiles' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'Shortcuts' to value '1'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'PrependPath' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'CompileAll' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing numeric variable 'SimpleInstall' to value '0'
[17C0:17D4][2015-11-15T10:07:17]i000: Initializing string variable 'SimpleInstallDescription' to value ''
[17C0:17D4][2015-11-15T10:07:17]i009: Command Line: '/modify'
[17C0:17D4][2015-11-15T10:07:17]i000: Setting string variable 'WixBundleLog' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717.log'
[17C0:17D4][2015-11-15T10:07:17]i000: Setting string variable 'WixBundleManufacturer' to value 'Python Software Foundation'
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'CRTInstalled' to value 0
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_debug' to value 0
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_symbols' to value 0
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_dev' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_doc' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_exe' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_lib' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'PrependPath' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_pip' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_tcltk' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_test' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Include_tools' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting numeric variable 'Shortcuts' to value 1
[17C0:17D4][2015-11-15T10:07:18]i000: Setting string variable 'InstallAllUsersState' to value 'disable'
[17C0:17D4][2015-11-15T10:07:18]i000: Setting string variable 'TargetDir' to value 'C:\Documents and Settings\Spravce\Local Settings\Data aplikac?\Programs\Python\Python35-32\'
[17C0:09B8][2015-11-15T10:07:18]i000: Did not find j:\dokumenty\install\Nstroje\python35\unattend.xml
[17C0:09B8][2015-11-15T10:07:18]i000: Setting string variable 'ActionLikeInstalling' to value 'Updating'
[17C0:09B8][2015-11-15T10:07:18]i000: Setting string variable 'ActionLikeInstallation' to value 'Modify'
[17C0:09B8][2015-11-15T10:07:18]i000: Setting version variable 'WixBundleFileVersion' to value '3.5.150.0'
[17C0:17D4][2015-11-15T10:07:18]i100: Detect begin, 54 packages
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.0_x86, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.0_x64, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.1_x86, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.1_x64, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.2_x86, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.2_x64, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.3_x86, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: crt_14.0_v6.3_x64, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_AllUsers_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_JustForMe_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: core_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: dev_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: dev_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: dev_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: dev_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: exe_AllUsers, feature: DefaultFeature, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: exe_AllUsers, feature: Shortcuts, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_AllUsers_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: exe_JustForMe, feature: DefaultFeature, state: Local
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: exe_JustForMe, feature: Shortcuts, state: Local
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_JustForMe_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: exe_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_AllUsers_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_JustForMe_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: lib_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_AllUsers_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_JustForMe_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: test_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: doc_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: doc_AllUsers, feature: DefaultFeature, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: doc_AllUsers, feature: Shortcuts, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: doc_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: doc_JustForMe, feature: DefaultFeature, state: Local
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: doc_JustForMe, feature: Shortcuts, state: Local
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tools_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tools_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_AllUsers, feature: DefaultFeature, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_AllUsers, feature: AssociateFiles, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_AllUsers, feature: Shortcuts, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_AllUsers_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_AllUsers_pdb, feature: Symbols, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_AllUsers_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_AllUsers_d, feature: DebugBinaries, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_JustForMe, feature: DefaultFeature, state: Local
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_JustForMe, feature: AssociateFiles, state: Local
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_JustForMe, feature: Shortcuts, state: Local
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_JustForMe_pdb, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_JustForMe_pdb, feature: Symbols, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: tcltk_JustForMe_d, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: tcltk_JustForMe_d, feature: DebugBinaries, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: launcher_AllUsers, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: launcher_AllUsers, feature: DefaultFeature, state: Local
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: launcher_AllUsers, feature: AssociateFiles, state: Local
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: launcher_JustForMe, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: launcher_JustForMe, feature: DefaultFeature, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i104: Detected package: launcher_JustForMe, feature: AssociateFiles, state: Absent
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: pip_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: pip_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: path_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: path_JustForMe, state: Present, cached: Complete
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: compileall_AllUsers, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i101: Detected package: compileall_JustForMe, state: Absent, cached: None
[17C0:17D4][2015-11-15T10:07:18]i199: Detect complete, result: 0x0
[17C0:09B8][2015-11-15T10:07:22]i000: Setting string variable 'ActionLikeInstalling' to value 'Repairing'
[17C0:09B8][2015-11-15T10:07:22]i000: Setting string variable 'ActionLikeInstallation' to value 'Repair'
[17C0:17D4][2015-11-15T10:07:22]i200: Plan begin, 54 packages, action: Repair
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT = v6.0 and not VersionNT64 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.0_x86
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT64 = v6.0 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.0_x64
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT = v6.1 and not VersionNT64 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.1_x86
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT64 = v6.1 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.1_x64
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT = v6.2 and not VersionNT64 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.2_x86
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT64 = v6.2 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.2_x64
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT = v6.3 and not VersionNT64 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.3_x86
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not CRTInstalled and VersionNT64 = v6.3 and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: crt_14.0_v6.3_x64
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: core_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: core_AllUsers_pdb, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: core_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_core_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_000_core_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_core or Include_exe or Include_launcher or Include_pip) and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_dev and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: dev_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_dev and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: dev_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_dev and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_dev_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_001_dev_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_dev and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: exe_AllUsers
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: exe_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: exe_AllUsers_pdb, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: exe_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: exe_JustForMe
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_exe_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_002_exe_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and (Include_exe or Include_launcher or Include_pip) and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_lib and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: lib_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_lib and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: lib_AllUsers_pdb, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_lib and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: lib_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_lib and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_lib_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_003_lib_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_lib and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_lib and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_test and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: test_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_test and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: test_AllUsers_pdb, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_test and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: test_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_test and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_test_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_004_test_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_test and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_test and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_doc and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: doc_AllUsers
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: doc_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_doc and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: doc_JustForMe
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_doc_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_005_doc_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_tools and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: tools_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_tools and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_tools_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_006_tools_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_tcltk and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 3 msi features for package: tcltk_AllUsers
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: AssociateFiles, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: tcltk_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_tcltk and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 1 msi features for package: tcltk_AllUsers_pdb
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Symbols, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: tcltk_AllUsers_pdb, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_tcltk and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 1 msi features for package: tcltk_AllUsers_d
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DebugBinaries, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: tcltk_AllUsers_d, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_tcltk and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 3 msi features for package: tcltk_JustForMe
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: AssociateFiles, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Shortcuts, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_tcltk_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_007_tcltk_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_tcltk and Include_symbols and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 1 msi features for package: tcltk_JustForMe_pdb
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: Symbols, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_tcltk and Include_debug and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 1 msi features for package: tcltk_JustForMe_d
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DebugBinaries, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i052: Condition '(InstallAllUsers or InstallLauncherAllUsers) and Include_launcher' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: launcher_AllUsers
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: AssociateFiles, state: Local, default requested: Unknown, ba requested: Local, execute action: Reinstall, rollback action: None
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: launcher_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_launcher_AllUsers' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_008_launcher_AllUsers.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not (InstallAllUsers or InstallLauncherAllUsers) and Include_launcher' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]i204: Plan 2 msi features for package: launcher_JustForMe
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: DefaultFeature, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i203: Planned feature: AssociateFiles, state: Absent, default requested: Unknown, ba requested: Local, execute action: AddLocal, rollback action: Remove
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and Include_pip and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: pip_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and Include_pip and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_pip_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_009_pip_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and PrependPath and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w322: Skipping cross-scope dependency registration on package: path_AllUsers, bundle scope: PerUser, package scope: PerMachine
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and PrependPath and not LauncherOnly' evaluates to true.
[17C0:17D4][2015-11-15T10:07:22]i000: Setting string variable 'WixBundleLog_path_JustForMe' to value 'C:\DOCUME~1\Spravce\LOCALS~1\Temp\Python 3.5.0 (32-bit)_20151115100717_010_path_JustForMe.log'
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'InstallAllUsers and CompileAll and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: compileall_AllUsers
[17C0:17D4][2015-11-15T10:07:22]i052: Condition 'not InstallAllUsers and CompileAll and not LauncherOnly' evaluates to false.
[17C0:17D4][2015-11-15T10:07:22]w321: Skipping dependency registration on package with no dependency providers: compileall_JustForMe
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.0_x86, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.0_x64, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.1_x86, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.1_x64, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.2_x86, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.2_x64, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.3_x86, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: crt_14.0_v6.3_x64, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_AllUsers_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_JustForMe_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: core_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: dev_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: dev_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: dev_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: dev_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_AllUsers_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_JustForMe_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: exe_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_AllUsers_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_JustForMe_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: lib_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_AllUsers_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_JustForMe_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: test_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: doc_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: doc_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tools_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tools_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_AllUsers_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_AllUsers_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_JustForMe_pdb, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: tcltk_JustForMe_d, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: launcher_AllUsers, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: launcher_JustForMe, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: pip_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: pip_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: path_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: path_JustForMe, state: Present, default requested: Repair, ba requested: Repair, execute: Repair, rollback: None, cache: No, uncache: No, dependency: Register
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: compileall_AllUsers, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i201: Planned package: compileall_JustForMe, state: Absent, default requested: Absent, ba requested: Absent, execute: None, rollback: None, cache: No, uncache: No, dependency: None
[17C0:17D4][2015-11-15T10:07:22]i299: Plan complete, result: 0x0
[17C0:17D4][2015-11-15T10:07:22]i300: Apply begin
[17C0:17D4][2015-11-15T10:08:24]i399: Apply complete, result: 0x8007015e, restart: Required, ba requested restart:  No

From adrien.georges.louis.viala at gmail.com  Sun Nov 15 06:31:06 2015
From: adrien.georges.louis.viala at gmail.com (Adrien Viala)
Date: Sun, 15 Nov 2015 11:31:06 +0000
Subject: uninstall 3.5
Message-ID: <CAA8KRpix8GeTvTMeNAWadUppAXgRjaoPssrKKiXehyWjYtHcVg@mail.gmail.com>

Hello,

Thank you for your work. Just discovering python.

My issue steps were  :
- 3.5 installed
- friend codes in 2.7
- server scripts can t run on my laptop (cant find module 0o)
- whatever, must be 3.5 / 2.7 issues
- let's try virtualenv
- can t download virtualenvwrapper-powershell : error X that i can t find
info about on googl
- whatever let's uninstall 3.5

:/


From adrien.georges.louis.viala at gmail.com  Sun Nov 15 06:46:05 2015
From: adrien.georges.louis.viala at gmail.com (Adrien Viala)
Date: Sun, 15 Nov 2015 11:46:05 +0000
Subject: uninstall 3.5
In-Reply-To: <CAA8KRpix8GeTvTMeNAWadUppAXgRjaoPssrKKiXehyWjYtHcVg@mail.gmail.com>
References: <CAA8KRpix8GeTvTMeNAWadUppAXgRjaoPssrKKiXehyWjYtHcVg@mail.gmail.com>
Message-ID: <CAA8KRpjiVFq9F6p9=h97Db7+4w_yKB=OyTffjFG7P8D6b3ZVmw@mail.gmail.com>

Hi again, Correct guess, virtualenvwrapper-powershell correctly installed
under 2.7 :)

On Sun, 15 Nov 2015 at 12:31 Adrien Viala <
adrien.georges.louis.viala at gmail.com> wrote:

> Hello,
>
> Thank you for your work. Just discovering python.
>
> My issue steps were  :
> - 3.5 installed
> - friend codes in 2.7
> - server scripts can t run on my laptop (cant find module 0o)
> - whatever, must be 3.5 / 2.7 issues
> - let's try virtualenv
> - can t download virtualenvwrapper-powershell : error X that i can t find
> info about on googl
> - whatever let's uninstall 3.5
>
> :/
>
>
>


From kent at z-sverige.nu  Sun Nov 15 07:38:25 2015
From: kent at z-sverige.nu (kent nyberg)
Date: Sun, 15 Nov 2015 07:38:25 -0500
Subject: pygtk beginner script not working
In-Reply-To: <5b6f7b3f-a132-4305-8ab7-a256b9dbf40f@googlegroups.com>
References: <5b6f7b3f-a132-4305-8ab7-a256b9dbf40f@googlegroups.com>
Message-ID: <20151115123825.GA24284@z-sverige.nu>


On Sat, Nov 14, 2015 at 05:00:59PM -0800, james at imagewebdesign.co.uk wrote:
> Hi guys
> 
> I'm new to Python so please bare with me :)
> 
> I'm using python 2.7.10 as advised (more tools apparently over 3.x)
> 
> Trying to use this script
> 
> [CODE]
> #!/usr/bin/env python
> 
> # example base.py
> 
> import pygtk

It makes most sense to use gtk3 and not gtk2.
The most recenst version of gtk3 is used with
gi package.

Read this for example:
http://python-gtk-3-tutorial.readthedocs.org/en/latest/introduction.html



From Seymore4Head at Hotmail.invalid  Sun Nov 15 12:30:49 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Sun, 15 Nov 2015 12:30:49 -0500
Subject: Format numbers
Message-ID: <jofh4bdq3m53tm9vn2m5066cag6ssmhv7a@4ax.com>

Just screwing around making up practice problems.  I can't get the
format right.  I am trying to learn how to get a output line to line
up neatly.

import random
lo=1
hi=10000 # I am adding or subtracting 0s from this input number
fm=len(str(hi)) # This counts the digits of the input number
print fm
a=random.randrange(lo,hi+1)
count=0
guess=0

while guess != a:
    guess=random.randrange(lo,hi + 1)
    print "guess =",

    print "{:8d}".format(guess),      #what I would like to do is use
the variable fm instead of the number 8 here so the number of fields
are the same as the input number.

    count+=1
    if guess==a:
        print " The hidden number was",a
        print
        print "You guessed right in ",
    if guess >a:
        print " Guess Lower"
        hi=guess
    if guess < a:
        lo=guess
        print " Guess Higher"  
print count
print " turns"


From python at mrabarnett.plus.com  Sun Nov 15 14:00:42 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Sun, 15 Nov 2015 19:00:42 +0000
Subject: Format numbers
In-Reply-To: <jofh4bdq3m53tm9vn2m5066cag6ssmhv7a@4ax.com>
References: <jofh4bdq3m53tm9vn2m5066cag6ssmhv7a@4ax.com>
Message-ID: <5648D65A.50900@mrabarnett.plus.com>

On 2015-11-15 17:30, Seymore4Head wrote:
> Just screwing around making up practice problems.  I can't get the
> format right.  I am trying to learn how to get a output line to line
> up neatly.
>
> import random
> lo=1
> hi=10000 # I am adding or subtracting 0s from this input number
> fm=len(str(hi)) # This counts the digits of the input number
> print fm
> a=random.randrange(lo,hi+1)
> count=0
> guess=0
>
> while guess != a:
>      guess=random.randrange(lo,hi + 1)
>      print "guess =",
>
>      print "{:8d}".format(guess),      #what I would like to do is use
> the variable fm instead of the number 8 here so the number of fields
> are the same as the input number.
>
>      count+=1
>      if guess==a:
>          print " The hidden number was",a
>          print
>          print "You guessed right in ",
>      if guess >a:
>          print " Guess Lower"
>          hi=guess
>      if guess < a:
>          lo=guess
>          print " Guess Higher"
> print count
> print " turns"
>
The part of the format placeholder that specifies the width can also be
placeholder, like this:

     print "{:{}d}".format(guess, fm)



From Seymore4Head at Hotmail.invalid  Sun Nov 15 14:07:12 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Sun, 15 Nov 2015 14:07:12 -0500
Subject: Format numbers
References: <jofh4bdq3m53tm9vn2m5066cag6ssmhv7a@4ax.com>
 <mailman.352.1447614048.16136.python-list@python.org>
Message-ID: <hulh4b11ddckoie99b049gdqmte7oali3m@4ax.com>

On Sun, 15 Nov 2015 19:00:42 +0000, MRAB <python at mrabarnett.plus.com>
wrote:

>On 2015-11-15 17:30, Seymore4Head wrote:
>> Just screwing around making up practice problems.  I can't get the
>> format right.  I am trying to learn how to get a output line to line
>> up neatly.
>>
>> import random
>> lo=1
>> hi=10000 # I am adding or subtracting 0s from this input number
>> fm=len(str(hi)) # This counts the digits of the input number
>> print fm
>> a=random.randrange(lo,hi+1)
>> count=0
>> guess=0
>>
>> while guess != a:
>>      guess=random.randrange(lo,hi + 1)
>>      print "guess =",
>>
>>      print "{:8d}".format(guess),      #what I would like to do is use
>> the variable fm instead of the number 8 here so the number of fields
>> are the same as the input number.
>>
>>      count+=1
>>      if guess==a:
>>          print " The hidden number was",a
>>          print
>>          print "You guessed right in ",
>>      if guess >a:
>>          print " Guess Lower"
>>          hi=guess
>>      if guess < a:
>>          lo=guess
>>          print " Guess Higher"
>> print count
>> print " turns"
>>
>The part of the format placeholder that specifies the width can also be
>placeholder, like this:
>
>     print "{:{}d}".format(guess, fm)

That works
Thanks


From j.bak36 at gmail.com  Sun Nov 15 15:38:40 2015
From: j.bak36 at gmail.com (jbak36)
Date: Sun, 15 Nov 2015 12:38:40 -0800 (PST)
Subject: Why won't this run?
Message-ID: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>

Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64 bit (AMD64)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> #this program says hello and asks for my name
>>> print:('Hello world!')
Hello world!
>>> print:('What is your name?') #ask for their name
What is your name?
>>> myName = input()
print:('It is good to meet you,'+myName)
>>> print:('The length of your name is:')
The length of your name is:
>>> print:(len(myName))
39
>>> print:('What is your age?')#ask for their age
What is your age?
>>> myAge=input()
print:('You will be ' + str(int(myAge)+1)'in a year.')
>>> 


From gherron at digipen.edu  Sun Nov 15 15:50:12 2015
From: gherron at digipen.edu (Gary Herron)
Date: Sun, 15 Nov 2015 12:50:12 -0800
Subject: Why won't this run?
In-Reply-To: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
References: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
Message-ID: <5648F004.6080101@digipen.edu>

On 11/15/2015 12:38 PM, jbak36 wrote:
> Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64 bit (AMD64)] on win32
> Type "copyright", "credits" or "license()" for more information.
>>>> #this program says hello and asks for my name
>>>> print:('Hello world!')
> Hello world!
>

You are lying to us somehow.  That attempt to print (as you've written 
it) does not produce the the line of output you've indicated.  Instead 
it produces a syntax error, because Python does not use a colon in that 
situation.

So change your print:(...) lines to print(...) (without the colon) and 
try again.  If there is further trouble, ask another question, but 
please cut and paste the actual and *exact* results into the email.

Gary Herron


-- 
Dr. Gary Herron
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418



From python.list at tim.thechases.com  Sun Nov 15 15:55:45 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 15 Nov 2015 14:55:45 -0600
Subject: Why won't this run?
In-Reply-To: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
References: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
Message-ID: <20151115145545.3fe779ac@bigbox.christie.dr>

On 2015-11-15 12:38, jbak36 wrote:
> Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC
> v.1900 64 bit (AMD64)] on win32 Type "copyright", "credits" or
> "license()" for more information.
> >>> #this program says hello and asks for my name
> >>> print:('Hello world!')
> Hello world!

Well, for starters, you're almost certainly not copy/pasting from the
shell session as the colon after the "print" is a syntax error:

  Python 3.4.2 (default, Oct  8 2014, 10:45:20) 
  [GCC 4.9.1] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  >>> print:('hellow world!')
    File "<stdin>", line 1
      print:('hellow world!')
           ^
  SyntaxError: invalid syntax

-tkc






From rxjwg98 at gmail.com  Sun Nov 15 19:27:03 2015
From: rxjwg98 at gmail.com (fl)
Date: Sun, 15 Nov 2015 16:27:03 -0800 (PST)
Subject: What meaning is 'a[0:10:2]'?
Message-ID: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>

hi,

When I learn slice, I have a new question on the help file. If I set:

pp=a[0:10:2]

pp is array([1, 3])

I don't know how a[0:10:2] gives array([1, 3]).

I know matlab a lot, but here it seems quite different. Could you tell me
what meaning a[0:10:2] is?


Thanks,



class slice(object)
 |  slice(stop)
 |  slice(start, stop[, step])
 |  
 |  Create a slice object.  This is used for extended slicing (e.g. a[0:10:2]).


From ben+python at benfinney.id.au  Sun Nov 15 19:46:19 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 16 Nov 2015 11:46:19 +1100
Subject: What meaning is 'a[0:10:2]'?
References: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>
Message-ID: <85ziyedb50.fsf@benfinney.id.au>

(Please set a ?From? address that has a name for you as an individual;
?fl? is rather anonymous and doesn't help us to identify you in these
conversations.)

fl <rxjwg98 at gmail.com> writes:

> When I learn slice

Are you working through the Python tutorial
<URL:https://docs.python.org/3/tutorial/>? These are Python concepts
that you will learn by working through the tutorial, from beginning to
end.

If you want to engage with a community dedicated to teaching Python
newcomers, you should join the Python ?tutor? forum
<URL:https://mail.python.org/mailman/listinfo/tutor>.

-- 
 \       ?Philosophy is questions that may never be answered. Religion |
  `\              is answers that may never be questioned.? ?anonymous |
_o__)                                                                  |
Ben Finney



From python.list at tim.thechases.com  Sun Nov 15 19:48:04 2015
From: python.list at tim.thechases.com (Tim Chase)
Date: Sun, 15 Nov 2015 18:48:04 -0600
Subject: What meaning is 'a[0:10:2]'?
In-Reply-To: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>
References: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>
Message-ID: <20151115184804.7e89625b@bigbox.christie.dr>

On 2015-11-15 16:27, fl wrote:
> When I learn slice, I have a new question on the help file. If I
> set:
> 
> pp=a[0:10:2]
> 
> pp is array([1, 3])
> 
> I don't know how a[0:10:2] gives array([1, 3]).
> 
> I know matlab a lot, but here it seems quite different. Could you
> tell me what meaning a[0:10:2] is?

Well, if it a matlab.array was a well-behaved object it would just
give you "0".  As your copy/paste on the help for a slice stated, the
first number is where it starts (0), the second number is where it
ends (10, exclusive), and the 3rd number (2) is the stride.  To
demonstrate:

  >>> a = list(range(20))
  >>> a
  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
  >>> a[0:10:2]
  [0, 2, 4, 6, 8]
  >>> a[:10:2]
  [0, 2, 4, 6, 8]
  >>> a[0:10]
  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

So note that the stride of 2 provides every other one while a stride
of three provides every 3rd value

  >>> a[0:10:3]
  [0, 3, 6, 9]

-tkc




From paul.hermeneutic at gmail.com  Sun Nov 15 23:54:41 2015
From: paul.hermeneutic at gmail.com (paul.hermeneutic at gmail.com)
Date: Sun, 15 Nov 2015 21:54:41 -0700
Subject: What meaning is of '#!python'?
In-Reply-To: <CACL+1at=zb12B=Ji4Y_n=QygwFs7UDKxVrQ=iNvtSonzuAzgxA@mail.gmail.com>
References: <ed2472ca-7efb-4676-b49e-356260dd533c@googlegroups.com>
 <CAPTjJmoNjpFKUgfOiejtLTjLK+yqx-MAtdGzEj4QNxcuxq4T4Q@mail.gmail.com>
 <CAKJDb-OtX5giW9KRSTo5F1GDp=uLHsK3qaT0p=k5yrxj7met4g@mail.gmail.com>
 <CACL+1at=zb12B=Ji4Y_n=QygwFs7UDKxVrQ=iNvtSonzuAzgxA@mail.gmail.com>
Message-ID: <CAJ4+4argUB0GtPi=H6qgx5J0sFMTuN52Q0OGFVB_t7wSj-6SqA@mail.gmail.com>

The installer of some applications will replace the shebang to refer to a
specific version of Python. By doing so, it avoids problems when someone
upgrades the default Python version in the PATH.
On Nov 14, 2015 11:00 PM, "eryksun" <eryksun at gmail.com> wrote:

> On Sat, Nov 14, 2015 at 8:26 PM, Zachary Ware
> <zachary.ware+pylist at gmail.com> wrote:
> >
> > "#!python" is a valid shebang for the Python Launcher for Windows.
> > It's also a not-too-terrible placeholder for a Unix shebang meaning
> > "whichever Python you want it to be".  The better choice for use with
> > both platforms would be "#!/usr/bin/env python", though.
>
> The "/usr/bin/env python" virtual command searches the directories in
> PATH, trying each file extension from PATHEXT such as "python.COM",
> "python.EXE", and so on. You can also search for other programs such
> as "pypy". Note that qualifying "python" (but not other names) as
> "python2" or "python3.5" makes the launcher use the registry instead
> of searching PATH.
>
> "#!/usr/bin/python" may be better in some cases. This defaults to the
> latest installed version of 2.x (or 3.x if no 2.x is installed) that's
> configured in the Windows registry. Or specify "python2" or "python3"
> to use the latest 2.x or 3.x. These commands can be configured to use
> a particular major[.minor[-32]] version via the environment variables
> PY_PYTHON, PY_PYTHON2, and PY_PYTHON3. Or you can configure them
> instead by setting the "python", "python2" and "python3" keys in the
> [defaults] section of the configuration file "%LOCALAPPDATA%\py.ini".
> Note that the environment variable overrides the corresponding py.ini
> key.
>
> When portability isn't a concern you can use a Windows path in the
> shebang such as "#!C:\pypy40\pypy.exe".
>
> https://docs.python.org/3/using/windows.html#shebang-lines
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From greg.ewing at canterbury.ac.nz  Mon Nov 16 01:11:13 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 16 Nov 2015 19:11:13 +1300
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <mailman.351.1447603799.16136.python-list@python.org>
References: <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.338.1447541659.16136.python-list@python.org>
 <5647dc88$0$1592$c3e8da3$5496439d@news.astraweb.com>
 <mailman.351.1447603799.16136.python-list@python.org>
Message-ID: <datac3F7ojoU1@mid.individual.net>

Dennis Lee Bieber wrote:
> 	And we'd be left looking for a symbol for bitwise inversion.

Who needs negation when you have bitwise inversion?

minusx = ~x + 1

I know, it doesn't work for floats, but that's just
a simple matter of defining ~ on floats appropriately...

-- 
Greg


From greg.ewing at canterbury.ac.nz  Mon Nov 16 01:15:23 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 16 Nov 2015 19:15:23 +1300
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <mailman.334.1447520685.16136.python-list@python.org>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.334.1447520685.16136.python-list@python.org>
Message-ID: <datajrF7ojoU2@mid.individual.net>

Ian Kelly wrote:
> Unary integer division seems pretty silly since the only possible results
> would be 0, 1 or -1.

Ints are not the only thing that // can be applied to:

 >>> 1.0//0.01
99.0

-- 
Greg


From greg.ewing at canterbury.ac.nz  Mon Nov 16 01:19:39 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 16 Nov 2015 19:19:39 +1300
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <mailman.333.1447520661.16136.python-list@python.org>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.333.1447520661.16136.python-list@python.org>
Message-ID: <datartF7rotU1@mid.individual.net>

Chris Angelico wrote:
> Small problem: Since we have / and // operators, it's impossible to
> have a unary / operator:

No, it's not -- '//' is already recognised as a single
token distinct from '/ /'. You would just have to leave
a space or use parens in some cases.

-- 
Greg


From greg.ewing at canterbury.ac.nz  Mon Nov 16 01:30:54 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 16 Nov 2015 19:30:54 +1300
Subject: What is wrong this wrapper (decorator)?
In-Reply-To: <dafb679e-c94c-47d2-9209-ce2a86a673d6@googlegroups.com>
References: <dafb679e-c94c-47d2-9209-ce2a86a673d6@googlegroups.com>
Message-ID: <datbh0F80u3U1@mid.individual.net>

fl wrote:
> wrapper(sub(two, one))
> Out[38]: <function checker>

This doesn't do what you probably meant it to do.
It first calls sub() with arguments one and two, and
then passes the result of that (a Coordinate, if
sub is working properly) to wrapper(). Since
wrapper() expects a function, not a Coordinate,
that won't do anything useful.

What you probably meant to do is:

wrapper(sub)(one, two)

This passes the function sub to wrapper, which
returns another function; that function is then
called with arguments one and two.

-- 
Greg


From mjoerg.phone at gmail.com  Mon Nov 16 03:02:09 2015
From: mjoerg.phone at gmail.com (PythonDude)
Date: Mon, 16 Nov 2015 00:02:09 -0800 (PST)
Subject: numpy column_stack - why does this work?
In-Reply-To: <mailman.293.1447435057.16136.python-list@python.org>
References: <0b4725a8-a040-4bfb-b046-81c2e529447a@googlegroups.com>
 <mailman.293.1447435057.16136.python-list@python.org>
Message-ID: <96d95669-5cf5-4a33-ba51-878edd975e48@googlegroups.com>

On Friday, 13 November 2015 18:17:59 UTC+1, Ian  wrote:
> On Fri, Nov 13, 2015 at 8:37 AM, PythonDude <mjoexxxxx.com> wrote:
> > 3) I DON'T understand why the code doesn't look like this:
> >
> > means, stds = np.column_stack([
> >     for _ in xrange(n_portfolios):
> >       getMuSigma_from_PF(return_vec) ])
> 
> Because that would be invalid syntax; you can't put a for loop inside
> an expression like that. Your question is not about numpy.column_stack
> at all, but about list comprehensions. I suggest you start by reading
> this:
> 
> https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions
> 
> Then if you're still confused, come back and ask further questions.

Thank you very much, I'll look careful into that before asking again :-)


From ammammata at tiscalinet.it  Mon Nov 16 06:12:02 2015
From: ammammata at tiscalinet.it (Ammammata)
Date: Mon, 16 Nov 2015 11:12:02 +0000 (UTC)
Subject: A Program that prints the numbers from 1 to 100
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
 <n27tp6$ec5$1@dont-email.me>
Message-ID: <XnsA5547C234722Bammammatatiscalineti@46.4.82.189>

Il giorno Sat 14 Nov 2015 07:18:18p, *BartC* inviava su comp.lang.python il 
messaggio news:n27tp6$ec5$1 at dont-email.me. Vediamo cosa scrisse:

> Here's one way

+1 :)

-- 
/-\ /\/\ /\/\ /-\ /\/\ /\/\ /-\ T /-\
-=- -=- -=- -=- -=- -=- -=- -=- - -=-
>>>>>  http://www.bb2002.it :)  <<<<<
........... [ al lavoro ] ...........


From harirammanohar159 at gmail.com  Mon Nov 16 06:40:27 2015
From: harirammanohar159 at gmail.com (harirammanohar159 at gmail.com)
Date: Mon, 16 Nov 2015 03:40:27 -0800 (PST)
Subject: help in pexpect multiprocessing
In-Reply-To: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
References: <c0f3d85c-d801-4106-9e1c-a84a2c077a4d@googlegroups.com>
Message-ID: <73aaf275-3d2c-4148-8a43-204bd2cd128e@googlegroups.com>

On Monday, 9 November 2015 18:07:36 UTC+5:30, hariramm... at gmail.com  wrote:
> Hi,
> 
> I am using multiprocessing with pexpect, issue is whenever i call a function which is having expect(), its throwing error which is genuine as multiple threads are processing it same time (i/o prompt same time by multiple processes..so issues in picture...), so i want to use lock for that section alone to avoid it, but still fails in implementing it...can you help me
> 
> username = input('Enter your username: ')
> password = getpass.getpass()
> 
> s = pxssh.pxssh()
> s.login ('host','username','password')
> s.sendline ('ps -ef|grep java')
> s.prompt(timeout=1)
> 
> Try 1:
> 
> if condition == 'met':
>        np = len(list1)
>        p = multiprocessing.Pool(np)
>        p.map(stop, [(ds) for ds in list1])
> 
> def stop(ds):
>         s.sendline ('cd /usr')
>         if condition:
>                 lock = threading.Lock()
>                 lock.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 lock.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Try 2:
> 
> if condition == 'met':
>         lock = Lock()
>         for ds in list1:
>                 Process(target=stop, args=(ds,lock)).start()
> 
> def stop(ds,l):
>         s.sendline ('cd /usr')
>         if condition:
>                 l.acquire()
>                 s.expect('Enter username:')
>                 s.sendline ('user')
>                 s.expect('Enter password:*')
>                 s.sendline('pass')
>                 l.release()
>         s.prompt(timeout=200)
>         print('stopped ds...')
> 
> Both are giving me same trace..
> 
> pexpect.ExceptionPexpect: isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process?
> 
> Thanks in Advance

Hey Lucena,

Thank you for suggestion, yeah process queues doing the samething, creating new sesssion for each process and executing simulatenously.. requirement is served..

but still i want to tackle the situation with locks, but not able to as throwing the below error.

pexpect.ExceptionPexpect: isalive() encountered condition where "terminated" is 0, but there was no child process. Did someone else call waitpid() on our process? 


From snailcoder at retrosite.invalid  Mon Nov 16 06:53:07 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Mon, 16 Nov 2015 12:53:07 +0100
Subject: What is the right way to import a package?
In-Reply-To: <8e325d88-6ad1-46e3-a1fb-ef8c28dc50a8@googlegroups.com>
References: <8e325d88-6ad1-46e3-a1fb-ef8c28dc50a8@googlegroups.com>
Message-ID: <n2cfug$4ad$1@dont-email.me>

On 14/11/15 21:00, fl wrote:
> Hi,
>
> I want to use a code snippet found on-line. It has such content:
>
> from numpy import *
> dt = 0.1
> # Initialization of state matrices
> X = array([[0.0], [0.0], [0.1], [0.1]])
>
> # Measurement matrices
> Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
>
>
>
> When the above content is inside a .py document and running, there will be
>   an error:
>
> ---> 15 Y = array([[X[0,0] + abs(randn(1)[0])], [X[1,0] + abs(randn(1)[0])]])
>       16 #Y = ([[X[0,0]], [X[1,0] + 0]])
>
> NameError: name 'randn' is not defined
>
>
> But when I run the above line by line at the console (Canopy), there will be
> no error for the above line.
>
> My question is:
>
> The import and the following are wrong.
>
> X = array([[0.0], [0.0], [0.1], [0.1]])
>
> It should be:
>
> import numpy as np
> ...
> Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])
>
> This looks like the code I once saw. But the file when running has such
>   error:
>
> ---> 15 Y = np.array([[X[0,0] + abs(np.randn(1)[0])], [X[1,0] + abs(np.randn(1)[0])]])
>
> AttributeError: 'module' object has no attribute 'randn'
>
> When it is run line by line at the console, it has the same error.
>
> It is strange that the same content has errors depends on inside a file, or
> at CLI console.
>
> What is missing I don't realize? Thanks,
>
>

You can try :
from numpy import *
from numpy.random import *

HTH,

- Grobu -



From harirammanohar159 at gmail.com  Mon Nov 16 06:57:04 2015
From: harirammanohar159 at gmail.com (harirammanohar159 at gmail.com)
Date: Mon, 16 Nov 2015 03:57:04 -0800 (PST)
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
Message-ID: <85eea326-406d-4454-8c3a-859f1e464cfc@googlegroups.com>

On Saturday, 14 November 2015 23:04:40 UTC+5:30, Cai Gengyang  wrote:
> I want to write a program in Python that does this ----
> 
> "Write a program that prints the numbers from 1 to 100. But for multiples of three print "Fizz" instead of the number and for the multiples of five print "Buzz". For numbers which are multiples of both three and five print "FizzBuzz"."
> 
> How do I go about doing it ?

This would help, but try to write on your own to improve, else you cant make this going long....

i = 1

while i <= 100:
    if multipleof_3 and multipleof_5:
        print("FizzBuzz")
        ++i
    elif multipleof_3:
        print("Fizz")
        ++i
    elif multipleof_5:
        print("Buzz")
        ++i
    else:
        print(number)
        ++i


From steve at pearwood.info  Mon Nov 16 07:11:49 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 16 Nov 2015 23:11:49 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.334.1447520685.16136.python-list@python.org>
 <datajrF7ojoU2@mid.individual.net>
Message-ID: <5649c807$0$1615$c3e8da3$5496439d@news.astraweb.com>

On Mon, 16 Nov 2015 05:15 pm, Gregory Ewing wrote:

> Ian Kelly wrote:
>> Unary integer division seems pretty silly since the only possible results
>> would be 0, 1 or -1.
> 
> Ints are not the only thing that // can be applied to:
> 
>  >>> 1.0//0.01
> 99.0


Good catch!



-- 
Steven



From steve at pearwood.info  Mon Nov 16 07:29:08 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 16 Nov 2015 23:29:08 +1100
Subject: What meaning is 'a[0:10:2]'?
References: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>
Message-ID: <5649cc16$0$1592$c3e8da3$5496439d@news.astraweb.com>

On Mon, 16 Nov 2015 11:27 am, fl wrote:

> hi,
> 
> When I learn slice, I have a new question on the help file. If I set:
> 
> pp=a[0:10:2]
> 
> pp is array([1, 3])

Really? How do you get that answer? What is `a`?


> I don't know how a[0:10:2] gives array([1, 3]).

Neither do I, because you have not told us what `a` is.

But I know what `a[0:10:2]` *should* be:

it takes a copy of elements from a, starting at position 0, ending just
before position 10, and taking every second one.


py> a = list(range(100, 121))
py> print(a)
[100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114,
115, 116, 117, 118, 119, 120]

py> print(a[0:10])
[100, 101, 102, 103, 104, 105, 106, 107, 108, 109]

py> print(a[0:10:2])
[100, 102, 104, 106, 108]

py> print(a[0:10:3])
[100, 103, 106, 109]


By default, the first item is automatically 0, so these two slices are the
same:

a[0:10:2]
a[:10:2]


If the start or end position are out of range, the slice will only include
positions that actually exist:

py> a[:10000:5]
[100, 105, 110, 115, 120]




-- 
Steven



From rosuav at gmail.com  Mon Nov 16 07:35:37 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 16 Nov 2015 23:35:37 +1100
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <85eea326-406d-4454-8c3a-859f1e464cfc@googlegroups.com>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
 <85eea326-406d-4454-8c3a-859f1e464cfc@googlegroups.com>
Message-ID: <CAPTjJmqzU50GcRjLnrJbKuy2TYiDWvcFy7vi-wHO4fa3wNvBrA@mail.gmail.com>

On Mon, Nov 16, 2015 at 10:57 PM,  <harirammanohar159 at gmail.com> wrote:
> This would help, but try to write on your own to improve, else you cant make this going long....
>

Here's another version, but with a deliberate bug in it. You may use
this code if and only if your comprehension is sufficient to detect
and correct that bug.

next(filter(None,(print(next(filter(None,reversed(x)))) for x in
enumerate(itertools.islice(itertools.cycle(("Fizzbuzz",0,"","Fizz",not
"Fuzz","Buzz","Fizz",(),bytes(),"Fizz","Buzz",{},"Fizz",False,globals().get(math.pi))),1,101)))),None)

Actually... you know what, I think debugging THAT is a malicious prank
to pull on an experienced Python programmer; plus, if you're caught
submitting that for your project, you deserve all the shame you get.
Trust me, this is NOT good code. Here's the corrected version. It
works, but you do not want to use this.

next(filter(None,(print(next(filter(None,reversed(x)))) for x in
itertools.islice(enumerate(itertools.cycle(("Fizzbuzz",0,"","Fizz",not
"Fuzz","Buzz","Fizz",(),bytes(),"Fizz","Buzz",{},"Fizz",False,globals().get(math.pi)))),1,101))),None)

Enjoy!

ChrisA


From steve at pearwood.info  Mon Nov 16 07:57:31 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 16 Nov 2015 23:57:31 +1100
Subject: Names [was Re: What meaning is 'a[0:10:2]'?]
References: <237d9a48-6db3-48aa-89b4-66730cdced7d@googlegroups.com>
 <mailman.354.1447634788.16136.python-list@python.org>
Message-ID: <5649d2bd$0$1613$c3e8da3$5496439d@news.astraweb.com>

On Mon, 16 Nov 2015 11:46 am, Ben Finney wrote:

> (Please set a ?From? address that has a name for you as an individual;
> ?fl? is rather anonymous and doesn't help us to identify you in these
> conversations.)

As far as I know, there's only one "fl" who posts here. And "fl" as a
cognomen is no worse than such well-known examples as:

J.R. https://en.wikipedia.org/wiki/JR_(artist)

and https://en.wikipedia.org/wiki/Who_shot_J.R.%3F

M.J. https://en.wikipedia.org/wiki/Mary_Jane_Watson

djk (who you worked with for a number of years *wink*)

T.I. https://en.wikipedia.org/wiki/T.I.

not to mention many famous people who are frequently, but not exclusively,
known by initials:

JMS https://en.wikipedia.org/wiki/J._Michael_Straczynski
MLK https://en.wikipedia.org/wiki/Martin_Luther_King,_Jr.
JFK https://en.wikipedia.org/wiki/John_F._Kennedy


On-the-internet-nobody-can-tell-if-your-name-really-is-Mxyzptlk-ly yr's,


-- 
Steven



From steve at pearwood.info  Mon Nov 16 08:10:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 17 Nov 2015 00:10:20 +1100
Subject: Question about yield
References: <ac359441-8cca-496c-b5c2-d3e7d7ce15dd@googlegroups.com>
Message-ID: <5649d5bf$0$1605$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 01:37 pm, fl wrote:

> Hi,
> I have read a couple of tutorial on yield. The following code snippet
> still gives me a shock. I am told yield is a little like return. I only
> see one yield in the tutorial examples. Here it has two yields. And there
> are three variables following keyword yield.

Correct. `yield` exits the running function, but unlike `return`, the
function doesn't close down, it just pauses, ready to start up again when
you call next() on it.

Here is an example of an ordinary function:

py> def function():
...     return 1
...     return 2
...     return 3
...
py> function()
1
py> function()
1

Each time you call the function, it starts again at the beginning, and exits
after the first `return`. So the lines `return 2` and `return 3` are dead
code that never gets run.

Here is an example of a generator function with yield. Calling generators is
a bit different from calling a function: first you have to initialise them
by calling the function to create a "generator object", then you call the
next() function to advance to the next `yield` statement, and finally they
raise an exception when there are no more `yields`.

An example might help:

py> def generator():
...     yield 1
...     yield 2
...     yield 3
...
py> gen = generator()
py> next(gen)
1
py> next(gen)
2
py> next(gen)
3
py> next(gen)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration


To start the generator from the beginning again, you have to create a new
generator object by calling the function:

gen = generator()


Calling next() many times is often inconvenient. Normally you will iterate
over the generator:

for x in gen:
    print(x)

or you call collect all the items using list(). See example below.

Here is a generator which takes a list as argument, and returns a running
sum of the list values:

def running_sum(alist):
    total = 0
    for value in alist:
        total += value
        yield total


And here is an example of using it:

py> gen = running_sum(data)
py> list(gen)
[1, 3, 6, 16, 18, 18, 23]



-- 
Steven



From rosuav at gmail.com  Mon Nov 16 08:17:40 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 17 Nov 2015 00:17:40 +1100
Subject: WinXP invalid python 3.5 installation
In-Reply-To: <XN9.1RFom.6lbrKHvhi4s.1MI4uB@seznam.cz>
References: <XN9.1RFom.6lbrKHvhi4s.1MI4uB@seznam.cz>
Message-ID: <CAPTjJmo0GiUNsnuB189kfHnubs3+5xcNAAwi4LiKpVpArCHavw@mail.gmail.com>

On Sun, Nov 15, 2015 at 8:19 PM,  <lokotraktor at email.cz> wrote:
> I have downloaded the
> https://www.python.org/ftp/python/3.5.0/python-3.5.0.exe
> and have installed it on Windows XP Home Edition Version 2002 SP3 (I am the
> administrator, which is on czech laguage the word "Spravce".)

You're not going to be able to install Python 3.5 on Windows XP - the
latest Python doesn't support the old Windows. You can upgrade to
Windows 7 or 8 or 10, or downgrade to Python 3.4, or jump across to
Linux or some other OS. The installer for 3.5 currently isn't very
clear about the problem, but that's going to be changed in a couple of
weeks, so you'll know what your options are.

ChrisA


From steve at pearwood.info  Mon Nov 16 08:17:43 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 17 Nov 2015 00:17:43 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <5647e90c$0$1588$c3e8da3$5496439d@news.astraweb.com>
 <mailman.342.1447554248.16136.python-list@python.org>
Message-ID: <5649d77a$0$1585$c3e8da3$5496439d@news.astraweb.com>

On Sun, 15 Nov 2015 01:23 pm, Chris Angelico wrote:

> On Sun, Nov 15, 2015 at 1:08 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> number = +raw_input("enter a number: ")
>>
>> versus:
>>
>> text = raw_input("enter a number: ")
>> try:
>>     number = float(text)
>> except ValueError:
>>     number = int(text)
> 
> What kinds of strings can float() not handle but int() can, 

Heh, I think I got the order of them backwards. You should try to convert to
int first, and if that fails, try float.


> and in a 
> program that's going to group floats and ints together as "numbers",
> will they ever be useful? I'd be more likely to write this as simply:

Obviously this code assumes you want to distinguish between ints and floats
for some reason. In Python, unlike Lua, Javascript and a few others, we do
distinguish between ints and floats. Since they have different
capabilities, that may sometimes be useful:


py> 10.0 ** 400
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: (34, 'Numerical result out of range')
py> 10 ** 400
1000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000


-- 
Steven



From rosuav at gmail.com  Mon Nov 16 08:27:55 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 17 Nov 2015 00:27:55 +1100
Subject: Problems using struct pack/unpack in files, and reading them.
In-Reply-To: <5649d77a$0$1585$c3e8da3$5496439d@news.astraweb.com>
References: <20151113192045.GA9913@z-sverige.nu>
 <CALwzidknLk3w8NWJqhYXjCFy4uBm79dxhBn=oaXCtxfJu-d-_g@mail.gmail.com>
 <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <5647e90c$0$1588$c3e8da3$5496439d@news.astraweb.com>
 <mailman.342.1447554248.16136.python-list@python.org>
 <5649d77a$0$1585$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmqiUQhX-NmxDmuW98VJi1vm1miSNrvGG13r1YDBtTjNLQ@mail.gmail.com>

On Tue, Nov 17, 2015 at 12:17 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Sun, 15 Nov 2015 01:23 pm, Chris Angelico wrote:
>
>> On Sun, Nov 15, 2015 at 1:08 PM, Steven D'Aprano <steve at pearwood.info>
>> wrote:
>>> number = +raw_input("enter a number: ")
>>>
>>> versus:
>>>
>>> text = raw_input("enter a number: ")
>>> try:
>>>     number = float(text)
>>> except ValueError:
>>>     number = int(text)
>>
>> What kinds of strings can float() not handle but int() can,
>
> Heh, I think I got the order of them backwards. You should try to convert to
> int first, and if that fails, try float.

Ah! Yes, that makes sense then. I assumed this...

>> and in a
>> program that's going to group floats and ints together as "numbers",
>> will they ever be useful? I'd be more likely to write this as simply:

... on the basis of the "float first" check.

> Obviously this code assumes you want to distinguish between ints and floats
> for some reason. In Python, unlike Lua, Javascript and a few others, we do
> distinguish between ints and floats. Since they have different
> capabilities, that may sometimes be useful:
>
>
> py> 10.0 ** 400
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> OverflowError: (34, 'Numerical result out of range')
> py> 10 ** 400
> 1000000000000000000000000000000000000000000000000000000000000000000000000
> 0000000000000000000000000000000000000000000000000000000000000000000000000
> 0000000000000000000000000000000000000000000000000000000000000000000000000
> 0000000000000000000000000000000000000000000000000000000000000000000000000
> 0000000000000000000000000000000000000000000000000000000000000000000000000
> 000000000000000000000000000000000000

Right. If you check int() first and then float(), you can make use of
this. But if the user enters that string and you try to float() it, it
will work:

>>> float(str(int(10**400)))
inf

Hence my confusion. :)

With that small change, your code makes fine sense.

ChrisA


From harvesting at is.invalid  Mon Nov 16 08:39:50 2015
From: harvesting at is.invalid (Jussi Piitulainen)
Date: Mon, 16 Nov 2015 15:39:50 +0200
Subject: A Program that prints the numbers from 1 to 100
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
 <85eea326-406d-4454-8c3a-859f1e464cfc@googlegroups.com>
 <mailman.357.1447677345.16136.python-list@python.org>
Message-ID: <lf5fv06rrkp.fsf@ling.helsinki.fi>

Chris Angelico writes:
>
> Here's another version, but with a deliberate bug in it. [- -]

This one recycles fish in a way that looks a bit worrying but it seems
to work. If there's a bug, it's not deliberate. Except stopping at 15 is
deliberate.

from contextlib import contextmanager as fish
from collections import defaultdict as fowl
@fish
def fish(fish):
    chip = fowl(str)
    chip.update(((fowl(int)[fish],fish),))
    yield chip
with fish("Fish") as f, fish("Bush") as b:
    print(*("{}{}".format(f[k%3],b[k%5]) or k for k in range(1,16)))

# prints:
1 2 Fish 4 Bush Fish 7 8 Fish Bush 11 Fish 13 14 FishBush


From rosuav at gmail.com  Mon Nov 16 08:43:29 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 17 Nov 2015 00:43:29 +1100
Subject: A Program that prints the numbers from 1 to 100
In-Reply-To: <lf5fv06rrkp.fsf@ling.helsinki.fi>
References: <ddada022-49a4-418e-85a1-45cd6da015f7@googlegroups.com>
 <85eea326-406d-4454-8c3a-859f1e464cfc@googlegroups.com>
 <mailman.357.1447677345.16136.python-list@python.org>
 <lf5fv06rrkp.fsf@ling.helsinki.fi>
Message-ID: <CAPTjJmqO4RZwQqyFgpi+g=5TjPHh-WPwoJMdnAU1p6F2DojE5Q@mail.gmail.com>

On Tue, Nov 17, 2015 at 12:39 AM, Jussi Piitulainen
<harvesting at is.invalid> wrote:
> This one recycles fish in a way that looks a bit worrying but it seems
> to work.

Recycles fish?

http://www.saigan.com/kidscorner/comics/unhfulb.jpg

ChrisA


From lynto28 at gmail.com  Mon Nov 16 08:43:44 2015
From: lynto28 at gmail.com (Didymus)
Date: Mon, 16 Nov 2015 05:43:44 -0800 (PST)
Subject: pexpect matching?
Message-ID: <6b2adb7a-7f2f-48ba-afa7-28e597bb9948@googlegroups.com>

Greetings,

  I have the following code:

import pexpect

child = pexpect.spawn('/bin/bash')
i = child.expect_exact('bash-3.2$ ')

child.sendline("rpm -q --queryformat '%{VERSION}\\n' glibc")
i = child.expect (['2', '2.5', '2.52.5', pexpect.TIMEOUT])

print  child.before
print '---'
print  child.after

if i == 0:
    print 'We got 2'
elif i == 1:
    print 'We got 2.5'
elif i == 2:
    print ' We got 7'
elif i == 3:
    print 'Timed Out!'
else:
    print 'What happened?'

The output of the commandline is:

% rpm -q --queryformat '%{VERSION}\n' glibc
2.5
2.5


I've tried to use "\b", "^", "$" around the return stings and even expect_exact, but end up with it printing "We got 2". It's just mathcing the first character and not the entire string.

rpm -q --queryformat '%{VERSION}\n' glibc

---
2
We got 2

What am I doing wrong here? What do I need to tell the expect line  to grab the entire line back to check against?

Thanks
  Tom


From ian.g.kelly at gmail.com  Mon Nov 16 09:50:30 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 16 Nov 2015 07:50:30 -0700
Subject: uninstall 3.5
In-Reply-To: <CAA8KRpix8GeTvTMeNAWadUppAXgRjaoPssrKKiXehyWjYtHcVg@mail.gmail.com>
References: <CAA8KRpix8GeTvTMeNAWadUppAXgRjaoPssrKKiXehyWjYtHcVg@mail.gmail.com>
Message-ID: <CALwzid=qxbEH7u5_1Z+us32+eGTT22XnjqCnmyb5a-L_KdqCrw@mail.gmail.com>

On Nov 16, 2015 6:10 AM, "Adrien Viala" <
adrien.georges.louis.viala at gmail.com> wrote:
>
> Hello,
>
> Thank you for your work. Just discovering python.
>
> My issue steps were  :
> - 3.5 installed
> - friend codes in 2.7
> - server scripts can t run on my laptop (cant find module 0o)
> - whatever, must be 3.5 / 2.7 issues
> - let's try virtualenv
> - can t download virtualenvwrapper-powershell : error X that i can t find
> info about on googl
> - whatever let's uninstall 3.5

If your friend is writing code for 2.7 and not writing for 2/3
compatibility, then you're not going to be able to run that code in Python
3. A virtual env won't help with that, because it's still Python 3.

Get your friend to upgrade to Python 3, or to write compatible code (there
are tools to help with this), or install Python 2.7.


From zachary.ware+pylist at gmail.com  Mon Nov 16 11:42:29 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 16 Nov 2015 10:42:29 -0600
Subject: Running latest 32-bit Python on 64-bit system
In-Reply-To: <daltmhFas7qU1@mid.individual.net>
References: <daltmhFas7qU1@mid.individual.net>
Message-ID: <CAKJDb-MUqvKufXzobUoa46fnozjUoZUBWQjLe9Mnq5z23P5DPA@mail.gmail.com>

On Fri, Nov 13, 2015 at 4:52 AM, Christian Ullrich <chris at chrullrich.net> wrote:
> Hello,
>
> I have a problem with using the (otherwise nice) Python launcher. How can I
> get it to run the highest 32-bit Python on my 64-bit system? This is on
> Windows, but I think it applies to other OSes as well.
>
> My application runs (unmodified) with Python 3.[345], but only with the
> 32-bit version because it loads a DLL that has no 64-bit version available.
> I would like to run it on any system that has *any* suitable Python
> installed.
>
> However, with the shebang syntax supported by the launcher, I can only
> demand a 32-bit version if I also specify the Python minor version I want,
> and I don't necessarily know that in advance.
>
> I can code around that, of course, but I don't want to. If Python can select
> the 64-bit version to run by itself, it should also be able to for the
> 32-bit version, right?

I don't think there's currently a way to do what you want, but it
seems like a reasonable thing to do.  Would you mind raising an
enhancement request on bugs.python.org?

About the closest you could come currently would be to specify the
full path to the interpreter, but of course that may vary by machine.

-- 
Zach


From input/ldompeling at casema.nl  Mon Nov 16 12:12:12 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 16 Nov 2015 17:12:12 GMT
Subject: import module  pyttsx in windows IDLE failed
Message-ID: <M7o2y.42200$PO1.15738@fx08.ams1>

When I try to run this module in Windows IDLE I get this message:
How can I solve this problem.

Thanks

Traceback (most recent call last):
  File "C:\raspberrypi\recipe-578839-1.py", line 1, in <module>
    import pyttsx
ImportError: No module named 'pyttsx'

This is what I found on the internet:
-------------------------------------------------------------------
import pyttsx
engine = pyttsx.init()
engine.setProperty('rate', 70)

voices = engine.getProperty('voices')
for voice in voices:
    print ("Using voice:"), repr(voice)
    engine.setProperty('voice', voice.id)
    engine.say("Hi there, how's you ?")
    engine.say("A B C D E F G H I J K L M")
    engine.say("N O P Q R S T U V W X Y Z")
    engine.say("0 1 2 3 4 5 6 7 8 9")
    engine.say("Sunday Monday Tuesday Wednesday Thursday Friday Saturday")
    engine.say("Violet Indigo Blue Green Yellow Orange Red")
    engine.say("Apple Banana Cherry Date Guava")
engine.runAndWait()


-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From syedmwaliullah at gmail.com  Mon Nov 16 12:14:43 2015
From: syedmwaliullah at gmail.com (syedmwaliullah at gmail.com)
Date: Mon, 16 Nov 2015 09:14:43 -0800 (PST)
Subject: write data in Excel using python
Message-ID: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>

hi, 
I am trying to write Excel file suing output from another software where the output comes as myturnlist.Show()

The first part is for the output from the software which is saved in the clipboard. 

The big middle part works to open Excel and save the data into excel file called "TurnData.xlsx". 

For some reason it doesn't save the file. 

Any idea?

Thanks in advance.


import VisumPy.excel

# Write to Excel

myturnlist.Show()
turnData = myturnlist.SaveToClipboard(59,0)

excel = win32com.client.Dispatch("Excel.Application")
wb = excel.Workbooks.Add()
exce.Visible = True
wb.WorkSheets[0].Paste()
excel.activeWorkbook.SaveAs ("c:\TurnData.xlsx")

myturnlist.Close()


From recruiter.venkat36 at gmail.com  Mon Nov 16 12:21:01 2015
From: recruiter.venkat36 at gmail.com (recruiter.venkat36 at gmail.com)
Date: Mon, 16 Nov 2015 09:21:01 -0800 (PST)
Subject: Immediate Requirement for IIB/APM Administrator at Orlando, FL.
Message-ID: <669ddee7-0e76-45d2-95de-a126d304b4a4@googlegroups.com>


Hi , 

Hope you are doing Good, We have Immediate Requirement for IIB/APM Administrator, Kindly go through the Job Description Below and If interested Please Respond to this Mail.

Job Description:
Title: IIB/APM Administrator
Location: - Orlando, FL
Duration: - 3 Months

IBM Technical expert is needed to automate the installation and configuration of IIB in multiple environments. Automate the installation and configuration of IBM's APM and APM agents products as well.
 
Job Requirements:
*	Expertise in installation, configuration and implementation of IBM Products: IIB, APM
*	Hands-on expertise in jython, wsadmin, msqi and bash shell.
*	Multi-node on-premise configuration experience with the above products.
 
        Consultant will automate the following:
*	       the install and configuration of IIB
*	       the install and configuration of APM
*	       the install and configuration of APM agents 
1.     Scope
Various efforts underway to launch and use IBM's IIB and APM in our environment.  Before and/or at the start of this engagement, we expect one manual install of these products to have taken place in a non-production environment.  This scope of this position is to perform all work related to automating the install and configuration of these products for subsequent deployments, based on the installation and configuration performed during our initial manual install. 
 
2.     Detailed Description of the Services:
Consultant will act on behalf of Build Services team performing the following:
o   Perform all design and development activities around the automation stated above using provided frameworks.  Scripting is expected to use jython, wsadmin, mqsi, and bash shell as applicable. 
o   Ensure all developed automation is aligned to and works with build and continuous integration frameworks.
o   Automation must cover both the initial install and configuration of each product, in addition to providing a framework to make incremental configuration changes over time.
o   Automation must cover the ability to configure different environments, for example development, testing, etc.  Automation should not have to be updated for each environment; instead the automation and scripting should be able to read configuration parameters from the environment and/or a configuration file.
o   Perform all validation and documentation activities relation to the developed automation, working with applicable teams as required.
o   Perform development activities relating to the automation of component validation.
o   Support troubleshooting in relation to execution of using the automation for official environment builds.
o   Use provided toolsets and procedures for defect tracking.
o   Perform and participate in reviews, inspections, and turnover procedures to build stakeholders.
 
 
The client will assist with the following functions during the duration of this project:
The Integration and Middleware Technical Lead(s) will perform the following:
o   Provide final approval design for all automation and continuous integration presented by consultant.
o   Provide functional subject matter resources for consultants to work with during all project phases.
o   Provide virtual workstations with VPN connectivity for design and development activities.
o   Provide an R&D environment that can be used to test automation.
o   Provide licenses for applicable development and build tools.
o   Provide incident and defect tracking toolsets.
o   Frameworks to work within for build, deployment, and continuous integration deliverables.
o   Participate in reviews, inspections, and turnovers.
o   Provide information on architecture vision and artifacts.
o   Provide functional information about the applicable application environments.
o   Assist in problem resolution.
o   Approve technical specifications and manual install documentation referencing the initial environment install of which the automation should be based.
o   Provide information on existing configuration management tools.
o   Provide content in existing Best Practice Library
o   Provide functional information about the existing application environment.
o   Assist in problem resolution.
o   Provide review, inspection, and turnover process and procedures.

Awaiting for your reply

Thanks in Anticipation,
Val | IT Division Inc.|
Direct: 678-740-6997|
Val at itdivisioninc.com |www.ITDivisionInc.com| 
Disclaimer: To be removed from our mailing lists please reply back with the"REMOVE" in subject line. Sorry for any inconvenience.


From python at mrabarnett.plus.com  Mon Nov 16 12:28:09 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 16 Nov 2015 17:28:09 +0000
Subject: import module pyttsx in windows IDLE failed
In-Reply-To: <M7o2y.42200$PO1.15738@fx08.ams1>
References: <M7o2y.42200$PO1.15738@fx08.ams1>
Message-ID: <564A1229.4040504@mrabarnett.plus.com>

On 2015-11-16 17:12, input/ldompeling at casema.nl wrote:
> When I try to run this module in Windows IDLE I get this message:
> How can I solve this problem.
>
> Thanks
>
> Traceback (most recent call last):
>    File "C:\raspberrypi\recipe-578839-1.py", line 1, in <module>
>      import pyttsx
> ImportError: No module named 'pyttsx'
>
> This is what I found on the internet:
> -------------------------------------------------------------------
> import pyttsx
> engine = pyttsx.init()
> engine.setProperty('rate', 70)
>
> voices = engine.getProperty('voices')
> for voice in voices:
>      print ("Using voice:"), repr(voice)
>      engine.setProperty('voice', voice.id)
>      engine.say("Hi there, how's you ?")
>      engine.say("A B C D E F G H I J K L M")
>      engine.say("N O P Q R S T U V W X Y Z")
>      engine.say("0 1 2 3 4 5 6 7 8 9")
>      engine.say("Sunday Monday Tuesday Wednesday Thursday Friday Saturday")
>      engine.say("Violet Indigo Blue Green Yellow Orange Red")
>      engine.say("Apple Banana Cherry Date Guava")
> engine.runAndWait()
>
>
Have you installed pyttsx?



From input/ldompeling at casema.nl  Mon Nov 16 12:45:01 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 16 Nov 2015 17:45:01 GMT
Subject: import module pyttsx in windows IDLE failed
References: <mailman.369.1447694899.16136.python-list@python.org>
Message-ID: <xCo2y.42201$PO1.14489@fx08.ams1>

In reply to "MRAB" who wrote the following:
Have you installed pyttsx?

No, I did not.
Where can I find pyttsx to install ?

Thanks
---------------------------------------------------------------------
> On 2015-11-16 17:12, input/ldompeling at casema.nl wrote:
> > When I try to run this module in Windows IDLE I get this message:
> > How can I solve this problem.
> > 
> > Thanks
> > 
> > Traceback (most recent call last):
> >    File "C:\raspberrypi\recipe-578839-1.py", line 1, in <module>
> >      import pyttsx
> > ImportError: No module named 'pyttsx'
> > 
> > This is what I found on the internet:
> > -------------------------------------------------------------------
> > import pyttsx
> > engine = pyttsx.init()
> > engine.setProperty('rate', 70)
> > 
> > voices = engine.getProperty('voices')
> > for voice in voices:
> >      print ("Using voice:"), repr(voice)
> >      engine.setProperty('voice', voice.id)
> >      engine.say("Hi there, how's you ?")
> >      engine.say("A B C D E F G H I J K L M")
> >      engine.say("N O P Q R S T U V W X Y Z")
> >      engine.say("0 1 2 3 4 5 6 7 8 9")
> >      engine.say("Sunday Monday Tuesday Wednesday Thursday Friday Saturday")
> >      engine.say("Violet Indigo Blue Green Yellow Orange Red")
> >      engine.say("Apple Banana Cherry Date Guava")
> > engine.runAndWait()
> > 
> > 
> Have you installed pyttsx?




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From vindhyachal.takniki at gmail.com  Mon Nov 16 12:58:06 2015
From: vindhyachal.takniki at gmail.com (Vindhyachal Takniki)
Date: Mon, 16 Nov 2015 09:58:06 -0800 (PST)
Subject: Getting started Image processing python
Message-ID: <42aecae4-f219-425f-be6c-97e6cf059546@googlegroups.com>

1. I want to learn basic image processing in python. (working on raspberry pi 2 board)

2. I have a image with different color dots like red,white, etc.After taking image, need to identify how many are red,white etc. 
I am looking for free image processing libs for that. Which one is better for begineers : http://scikit-image.org/download.html  or http://opencv-python-tutroals.readthedocs.org/en/latest/index.html ?







From python at mrabarnett.plus.com  Mon Nov 16 13:12:51 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 16 Nov 2015 18:12:51 +0000
Subject: import module pyttsx in windows IDLE failed
In-Reply-To: <xCo2y.42201$PO1.14489@fx08.ams1>
References: <mailman.369.1447694899.16136.python-list@python.org>
 <xCo2y.42201$PO1.14489@fx08.ams1>
Message-ID: <564A1CA3.3000002@mrabarnett.plus.com>

On 2015-11-16 17:45, input/ldompeling at casema.nl wrote:
> In reply to "MRAB" who wrote the following:
> Have you installed pyttsx?
>
> No, I did not.
> Where can I find pyttsx to install ?
>
The first place to look is PyPI. It's here:

https://pypi.python.org/pypi/pyttsx

You might want to look at the links for the homepage and documentation.
That mentions a later version.

> Thanks
> ---------------------------------------------------------------------
>> On 2015-11-16 17:12, input/ldompeling at casema.nl wrote:
>> > When I try to run this module in Windows IDLE I get this message:
>> > How can I solve this problem.
>> >
>> > Thanks
>> >
>> > Traceback (most recent call last):
>> >    File "C:\raspberrypi\recipe-578839-1.py", line 1, in <module>
>> >      import pyttsx
>> > ImportError: No module named 'pyttsx'
>> >
>> > This is what I found on the internet:
>> > -------------------------------------------------------------------
>> > import pyttsx
>> > engine = pyttsx.init()
>> > engine.setProperty('rate', 70)
>> >
>> > voices = engine.getProperty('voices')
>> > for voice in voices:
>> >      print ("Using voice:"), repr(voice)
>> >      engine.setProperty('voice', voice.id)
>> >      engine.say("Hi there, how's you ?")
>> >      engine.say("A B C D E F G H I J K L M")
>> >      engine.say("N O P Q R S T U V W X Y Z")
>> >      engine.say("0 1 2 3 4 5 6 7 8 9")
>> >      engine.say("Sunday Monday Tuesday Wednesday Thursday Friday Saturday")
>> >      engine.say("Violet Indigo Blue Green Yellow Orange Red")
>> >      engine.say("Apple Banana Cherry Date Guava")
>> > engine.runAndWait()
>> >
>> >
>> Have you installed pyttsx?
>



From tjreedy at udel.edu  Mon Nov 16 13:20:28 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 16 Nov 2015 13:20:28 -0500
Subject: import module pyttsx in windows IDLE failed
In-Reply-To: <xCo2y.42201$PO1.14489@fx08.ams1>
References: <mailman.369.1447694899.16136.python-list@python.org>
 <xCo2y.42201$PO1.14489@fx08.ams1>
Message-ID: <n2d6pn$1gi$1@ger.gmane.org>

On 11/16/2015 12:45 PM, input/ldompeling at casema.nl wrote:
> In reply to "MRAB" who wrote the following:
> Have you installed pyttsx?
>
> No, I did not.
> Where can I find pyttsx to install ?

Let pip find it (its on pypi).
On a command line, enter 'pip install pyttsx'

-- 
Terry Jan Reedy



From motoom at xs4all.nl  Mon Nov 16 13:20:59 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Mon, 16 Nov 2015 19:20:59 +0100
Subject: write data in Excel using python
In-Reply-To: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>
References: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>
Message-ID: <9559B3D4-FF2F-4CCA-8C52-BF0D1988755E@xs4all.nl>


Hi,

> On 16 Nov 2015, at 18:14, syedmwaliullah at gmail.com wrote:
> For some reason it doesn't save the file.

Did you get an error message?

> excel.activeWorkbook.SaveAs ("c:\TurnData.xlsx")

When you use backslashes in strings, don't forget to escape them:

> excel.activeWorkbook.SaveAs("c:\\TurnData.xlsx")

or use raw strings:

> excel.activeWorkbook.SaveAs(r"c:\TurnData.xlsx")

Greetings,




From chris at chrullrich.net  Mon Nov 16 13:38:09 2015
From: chris at chrullrich.net (Christian Ullrich)
Date: Mon, 16 Nov 2015 19:38:09 +0100
Subject: Running latest 32-bit Python on 64-bit system
In-Reply-To: <mailman.368.1447692171.16136.python-list@python.org>
References: <daltmhFas7qU1@mid.individual.net>
 <mailman.368.1447692171.16136.python-list@python.org>
Message-ID: <daum5tFis26U1@mid.individual.net>

* Zachary Ware wrote:

> On Fri, Nov 13, 2015 at 4:52 AM, Christian Ullrich <chris at chrullrich.net> wrote:

>> However, with the shebang syntax supported by the launcher, I can only
>> demand a 32-bit version if I also specify the Python minor version I want,
>> and I don't necessarily know that in advance.
>>
>> I can code around that, of course, but I don't want to. If Python can select
>> the 64-bit version to run by itself, it should also be able to for the
>> 32-bit version, right?
>
> I don't think there's currently a way to do what you want, but it
> seems like a reasonable thing to do.  Would you mind raising an
> enhancement request on bugs.python.org?

<https://bugs.python.org/issue25636>. Crossing my fingers ...

> About the closest you could come currently would be to specify the
> full path to the interpreter, but of course that may vary by machine.

And it would include the version number in either the path (Windows) or 
the file name (elsewhere) again, rather defeating the purpose.

Thanks for your help,

-- 
Christian




From input/ldompeling at casema.nl  Mon Nov 16 15:03:30 2015
From: input/ldompeling at casema.nl (input/ldompeling at casema.nl)
Date: Mon, 16 Nov 2015 20:03:30 GMT
Subject: import module pyttsx in windows IDLE failed
References: <mailman.371.1447698071.16136.python-list@python.org>
Message-ID: <mEq2y.106808$ZM.8705@fx11.ams1>

Now I get this error:

Traceback (most recent call last):
  File "C:\raspberrypi\recipe-578839-1.py", line 1, in <module>
    import pyttsx
  File "C:\Users\loek\AppData\Local\Programs\Python\Python35\lib\site-packages\pyttsx\__init__.py", line 18, in <module>
    from engine import Engine
ImportError: No module named 'engine'
===========================================================================================================================



In reply to "Terry Reedy" who wrote the following:

> On 11/16/2015 12:45 PM, input/ldompeling at casema.nl wrote:
> > In reply to "MRAB" who wrote the following:
> > Have you installed pyttsx?
> > 
> > No, I did not.
> > Where can I find pyttsx to install ?
> 
> Let pip find it (its on pypi).
> On a command line, enter 'pip install pyttsx'
> 
> --
> Terry Jan Reedy




-- 
--------------------------------- --- -- -
Posted with NewsLeecher v7.0 Beta 2
Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -



From acropolis7844 at yahoo.com  Mon Nov 16 16:08:33 2015
From: acropolis7844 at yahoo.com (Robert Ziomkowski)
Date: Mon, 16 Nov 2015 21:08:33 +0000 (UTC)
Subject: Trouble installing Python 3.5.0
References: <1479749727.6211494.1447708113131.JavaMail.yahoo.ref@mail.yahoo.com>
Message-ID: <1479749727.6211494.1447708113131.JavaMail.yahoo@mail.yahoo.com>

Hello,

I installed 3.5, "successfully" as the installer indicated, yet the program wouldn't run, with the following error message: "...failed to start because api-ms-win-crt-runtime-I1-1-0.dll was not found. Re-installing the application may fix this problem." I reinstalled, but no luck. 

I noticed during installation that all the files were 64-bit (as my computer is), except one: the Launcher appears as 32-bit. Could that be the source of the problem? (The error occurs during launch, after all.) The installer I used is "python-3.5.0-amd64.exe" downloaded from Python.org directly. Could you have accidentally shipped the 32-bit Launcher with the 64-bit exe?

There was one other wrinkle. When I first installed Python 3.5, I accidentally installed the 32-bit version, because it is what came up when I pressed the big yellow button for 3.5 on your site (next to the other yellow button for Python 2.7.10). In a moment of forgetfulness I didn't check for the 64-bit version. Could this have messed things up? I uninstalled a couple times, so it should have cleared things up. But maybe not?

I found the 64-bit version later, but it was a bit hard to find. Why are you putting the 32-bit version out front and center, and not offering an option for the 64-bit right next to it?

Best wishes,
Robert Z.

P.S. I'm running Vista, so my PC is a bit old, but it is in fact 64-bit, and Python 3.2 still runs fine on it.


From ian.g.kelly at gmail.com  Mon Nov 16 19:22:39 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 16 Nov 2015 17:22:39 -0700
Subject: write data in Excel using python
In-Reply-To: <9559B3D4-FF2F-4CCA-8C52-BF0D1988755E@xs4all.nl>
References: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>
 <9559B3D4-FF2F-4CCA-8C52-BF0D1988755E@xs4all.nl>
Message-ID: <CALwzidmBy9juYWpqPV_km1OUG-xjDbhTfCtMS13VAiWadaaE-g@mail.gmail.com>

On Mon, Nov 16, 2015 at 11:20 AM, Michiel Overtoom <motoom at xs4all.nl> wrote:
>
> Hi,
>
>> On 16 Nov 2015, at 18:14, syedmwaliullah at gmail.com wrote:
>> For some reason it doesn't save the file.
>
> Did you get an error message?
>
>> excel.activeWorkbook.SaveAs ("c:\TurnData.xlsx")
>
> When you use backslashes in strings, don't forget to escape them:
>
>> excel.activeWorkbook.SaveAs("c:\\TurnData.xlsx")
>
> or use raw strings:
>
>> excel.activeWorkbook.SaveAs(r"c:\TurnData.xlsx")

You can also just use a forward slash:

excel.activeWorkbook.SaveAs("c:/TurnData.xlsx")

Windows happily accepts this.


From tdsperth at gmail.com  Mon Nov 16 20:43:18 2015
From: tdsperth at gmail.com (tdsperth at gmail.com)
Date: Mon, 16 Nov 2015 17:43:18 -0800 (PST)
Subject: write data in Excel using python
In-Reply-To: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>
References: <3267f6a3-a047-4abf-80bf-8fdba3659223@googlegroups.com>
Message-ID: <317940a3-ac2f-4d0a-8ed5-9395cca9835b@googlegroups.com>

On Tuesday, November 17, 2015 at 1:14:56 AM UTC+8, SW wrote:
> hi, 
> I am trying to write Excel file suing output from another software where the output comes as myturnlist.Show()
> 
> The first part is for the output from the software which is saved in the clipboard. 
> 
> The big middle part works to open Excel and save the data into excel file called "TurnData.xlsx". 
> 
> For some reason it doesn't save the file. 
> 
> Any idea?
> 
> Thanks in advance.
> 
> 
> import VisumPy.excel
> 
> # Write to Excel
> 
> myturnlist.Show()
> turnData = myturnlist.SaveToClipboard(59,0)
> 
> excel = win32com.client.Dispatch("Excel.Application")
> wb = excel.Workbooks.Add()
> exce.Visible = True
> wb.WorkSheets[0].Paste()
> excel.activeWorkbook.SaveAs ("c:\TurnData.xlsx")
> 
> myturnlist.Close()

Take out exce.Visible = True ( which I believe is atypo)

Colin


From Seymore4Head at Hotmail.invalid  Mon Nov 16 23:29:01 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Mon, 16 Nov 2015 23:29:01 -0500
Subject: palindrome
Message-ID: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>

http://www.practicepython.org/exercise/2014/03/12/06-string-lists.html

Here is my answers.  What would make it better?

import random
str1=""
letcount=4
count=0
abc='abcdefghijklmnopqrstuvwxyz'
while True:
    for i in range(letcount):
        a=random.choice(abc)
        str1+=a
    print str1
    count+=1
    if str1==str1[::-1]:        
        break
    else:
        str1=""
print "Tries= ",count
print str1


From abhi.darkness at gmail.com  Mon Nov 16 23:39:27 2015
From: abhi.darkness at gmail.com (Abhiram R)
Date: Tue, 17 Nov 2015 10:09:27 +0530
Subject: palindrome
In-Reply-To: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
References: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
Message-ID: <CADgpKWa+rOX0VDrXy4Ss2wQpXgk+1tziWFXZx6aK1SWfdRjx1Q@mail.gmail.com>

On Tue, Nov 17, 2015 at 9:59 AM, Seymore4Head <Seymore4Head at hotmail.invalid>
wrote:

> http://www.practicepython.org/exercise/2014/03/12/06-string-lists.html
>
> Here is my answers.  What would make it better?
>
> import random
> str1=""
> letcount=4
> count=0
> abc='abcdefghijklmnopqrstuvwxyz'
> while True:
>     for i in range(letcount):
>         a=random.choice(abc)
>         str1+=a
>     print str1
>     count+=1
>     if str1==str1[::-1]:
>         break
>     else:
>         str1=""
> print "Tries= ",count
> print str1
> --
>
> ?

The question asks to get an input from the user and print if it's a
palindrome or not.
It should be just

strA=raw_input()
if strA==strA[::-1]:
    print "Palindrome"
else:
    print "Not"

Right? Am I missing something? Why are you generating random strings and
trying to check for palindromes??


Thanks
Abhiram R (IRC - abhiii5459_ ; Twitter - https://twitter.com/abhiii5459)


From Seymore4Head at Hotmail.invalid  Mon Nov 16 23:48:48 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Mon, 16 Nov 2015 23:48:48 -0500
Subject: palindrome
References: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
 <mailman.376.1447735216.16136.python-list@python.org>
Message-ID: <78cl4bljie79vqr80d1g084jm8ma3k0r9k@4ax.com>

On Tue, 17 Nov 2015 10:09:27 +0530, Abhiram R
<abhi.darkness at gmail.com> wrote:

>On Tue, Nov 17, 2015 at 9:59 AM, Seymore4Head <Seymore4Head at hotmail.invalid>
>wrote:
>
>> http://www.practicepython.org/exercise/2014/03/12/06-string-lists.html
>>
>> Here is my answers.  What would make it better?
>>
>> import random
>> str1=""
>> letcount=4
>> count=0
>> abc='abcdefghijklmnopqrstuvwxyz'
>> while True:
>>     for i in range(letcount):
>>         a=random.choice(abc)
>>         str1+=a
>>     print str1
>>     count+=1
>>     if str1==str1[::-1]:
>>         break
>>     else:
>>         str1=""
>> print "Tries= ",count
>> print str1
>> --
>>
>> ?
>
>The question asks to get an input from the user and print if it's a
>palindrome or not.
>It should be just
>
>strA=raw_input()
>if strA==strA[::-1]:
>    print "Palindrome"
>else:
>    print "Not"
>
>Right? Am I missing something? Why are you generating random strings and
>trying to check for palindromes??
>
The instructions do ask for input.  I am lazy.  I thought it would be
cool to have random input instead of just typing a phrase.


From abhi.darkness at gmail.com  Mon Nov 16 23:55:47 2015
From: abhi.darkness at gmail.com (Abhiram R)
Date: Tue, 17 Nov 2015 10:25:47 +0530
Subject: palindrome
In-Reply-To: <78cl4bljie79vqr80d1g084jm8ma3k0r9k@4ax.com>
References: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
 <mailman.376.1447735216.16136.python-list@python.org>
 <78cl4bljie79vqr80d1g084jm8ma3k0r9k@4ax.com>
Message-ID: <CADgpKWbZ6kVWR3kxSuBrM+kys3+7FCS8N5W1rvqMbGY7H7KGvQ@mail.gmail.com>

On Tue, Nov 17, 2015 at 10:18 AM, Seymore4Head <Seymore4Head at hotmail.invalid
> wrote:

> On Tue, 17 Nov 2015 10:09:27 +0530, Abhiram R
> <abhi.darkness at gmail.com> wrote:
>
> >On Tue, Nov 17, 2015 at 9:59 AM, Seymore4Head
> <Seymore4Head at hotmail.invalid>
> >wrote:
> >
> >> http://www.practicepython.org/exercise/2014/03/12/06-string-lists.html
> >>
> >> Here is my answers.  What would make it better?
> >>
> >> import random
> >> str1=""
> >> letcount=4
> >> count=0
> >> abc='abcdefghijklmnopqrstuvwxyz'
> >> while True:
> >>     for i in range(letcount):
> >>         a=random.choice(abc)
> >>         str1+=a
> >>     print str1
> >>     count+=1
> >>     if str1==str1[::-1]:
> >>         break
> >>     else:
> >>         str1=""
> >> print "Tries= ",count
> >> print str1
> >> --
> >>
> >> ?
> >
> >The question asks to get an input from the user and print if it's a
> >palindrome or not.
> >It should be just
> >
> >strA=raw_input()
> >if strA==strA[::-1]:
> >    print "Palindrome"
> >else:
> >    print "Not"
> >
> >Right? Am I missing something? Why are you generating random strings and
> >trying to check for palindromes??
> >
> The instructions do ask for input.  I am lazy.  I thought it would be
> cool to have random input instead of just typing a phrase.
> --
>
>
?Haha. Nice. Although with your length of string and the range you're
picking from,the chances of you getting a palindrome are (1/24!)  :D ?




-- 
-Abhiram R


From gandalf at shopzeus.com  Tue Nov 17 03:24:41 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Tue, 17 Nov 2015 09:24:41 +0100
Subject: pybabel: default locale is None ???
Message-ID: <564AE449.5010108@shopzeus.com>

Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64
bit (AMD64)] on win32
>>> from datetime import timedelta
>>> from babel.dates import format_timedelta
>>> td = timedelta(seconds=39.28355172422679)
>>> format_timedelta(td)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "C:\Python35\lib\site-packages\babel\dates.py", line 779, in
format_timedelta
    plural_form = locale.plural_form(value)
AttributeError: 'NoneType' object has no attribute 'plural_form'
>>> from babel.core import default_locale
>>> repr(default_locale('LC_CTIME'))
'None'


Why? The default_locale documentation tells this:

"Returns the system default locale for a given category, based on
environment variables."




From __peter__ at web.de  Tue Nov 17 04:31:37 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 10:31:37 +0100
Subject: palindrome
References: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
Message-ID: <n2es5q$fbs$1@ger.gmane.org>

Seymore4Head wrote:

> http://www.practicepython.org/exercise/2014/03/12/06-string-lists.html
> 
> Here is my answers.  What would make it better?

1. Break the code into functions: one to generate a random string (the 
desired length could be a parameter) and one to check if the string is a 
palindrome. With that the loop will become

tries = 0
while True:
    tries += 1
    candidate = random_string(length=4)
    print(candidate)
    if is_palindrome(candidate):
        break
print(tries, "tries")

2. If you plan to reuse these functions put the above code in a function 
(let's call it main), too, that you invoke with

if __name__ == "__main__":
    main()

to avoid that the code is executed when you import the module instead of 
running it as a script.

3. For better readability add spaces around operators. There is a tool 
called pep8 that will point out where you are breaking the standard Python 
coding conventions.

4. Minor rewrites:
4.1 Can you rewrite the while loop as a for loop?

for tries in ...:
   ...

Hint 1: you can put a while loop into a generator
Hint 2: there's a ready-made solution in itertools.

4.2 Can you build the random string using a generator expression and 
"".join(...)?

> import random
> str1=""
> letcount=4
> count=0
> abc='abcdefghijklmnopqrstuvwxyz'
> while True:
>     for i in range(letcount):
>         a=random.choice(abc)
>         str1+=a
>     print str1
>     count+=1
>     if str1==str1[::-1]:
>         break
>     else:
>         str1=""
> print "Tries= ",count
> print str1




From __peter__ at web.de  Tue Nov 17 04:48:36 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 10:48:36 +0100
Subject: palindrome
References: <s4bl4bd739gfq92c5hipb16grv8a5fh5pb@4ax.com>
 <mailman.376.1447735216.16136.python-list@python.org>
 <78cl4bljie79vqr80d1g084jm8ma3k0r9k@4ax.com>
 <CADgpKWbZ6kVWR3kxSuBrM+kys3+7FCS8N5W1rvqMbGY7H7KGvQ@mail.gmail.com>
Message-ID: <n2et5m$uv7$1@ger.gmane.org>

Abhiram R wrote:

> ?Haha. Nice. Although with your length of string and the range you're
> picking from,the chances of you getting a palindrome are (1/24!)  :D ?

Are you sure?

>>> candidates = list(itertools.product(string.ascii_lowercase, repeat=4))
>>> len(candidates)/len([c for c in candidates if c == c[::-1]])
676.0

That looks like one in 26**(length//2)



From df at see.replyto.invalid  Tue Nov 17 04:54:31 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Tue, 17 Nov 2015 09:54:31 +0000
Subject: Problems using struct pack/unpack in files, and reading them.
References: <mailman.310.1447454532.16136.python-list@python.org>
 <56469f14$0$1612$c3e8da3$5496439d@news.astraweb.com>
 <mailman.314.1447470111.16136.python-list@python.org>
 <5646c95a$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.329.1447515842.16136.python-list@python.org>
 <87vb94ikuv.fsf@elektro.pacujo.net>
 <mailman.334.1447520685.16136.python-list@python.org>
 <datajrF7ojoU2@mid.individual.net>
 <5649c807$0$1615$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5isl4bpluclfm0fhj3aa7a4u4gj1n2c4nh@4ax.com>

Steven D'Aprano <steve at pearwood.info> wrote:

>On Mon, 16 Nov 2015 05:15 pm, Gregory Ewing wrote:
>
>> Ints are not the only thing that // can be applied to:
>> 
>>  >>> 1.0//0.01
>> 99.0
>
>Good catch!

Hmmm. I see that the float for 0.01 _is_ slightly larger than 0.01

>>> Decimal(0.01)
Decimal('0.01000000000000000020816681711721685132943093776702880859375')

But it seems that 1.0 // 0.01 is not directly equivalent to:

>>> int(1.0 / 0.01)
100

And I see that:

>>> Decimal(1.0 / 0.01)
Decimal('100')
>>> floor(1.0 / 0.01)
100
>>> 0.01 * 100.0 - 1.0
0.0

So I guess that the // operator is _very_ strict in its "floor division"
of floats, but that the "/" operator returns the nearest float value.


From michael at stroeder.com  Tue Nov 17 05:14:21 2015
From: michael at stroeder.com (=?UTF-8?Q?Michael_Str=c3=b6der?=)
Date: Tue, 17 Nov 2015 11:14:21 +0100
Subject: JOSE modules
Message-ID: <n2euhi$nlv$1@dont-email.me>

HI!

It seems there are already three modules for implementing JOSE (see RFC
7515..7520). :-/

Anyone here who has practical experience with any of them (with Python 2.7.x
and preferrably with elliptic curves)?

Ciao, Michael.

pyjwkest
https://pypi.python.org/pypi/pyjwkest

JWCrypto
https://pypi.python.org/pypi/jwcrypto
http://jwcrypto.readthedocs.org/en/stable/index.html

python-jose
https://pypi.python.org/pypi/python-jose


From alexander_naumov at opensuse.org  Tue Nov 17 05:44:42 2015
From: alexander_naumov at opensuse.org (Alex Naumov)
Date: Tue, 17 Nov 2015 11:44:42 +0100
Subject: HTTPSConnection from http.client?
Message-ID: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>

Hello,

does anybody know how to create a HTTPS connections in python2 or python3?
I tried second day to do that with http.client[1], but every time get error:

from http.client import HTTPSConnection
ImportError: cannot import name HTTPSConnection


Where is HTTPSConnection located? Which module?

I use openSUSE 13.1 x86_64.

Thank you,
Alex


[1] https://docs.python.org/3/library/http.client.html


From __peter__ at web.de  Tue Nov 17 06:22:50 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 12:22:50 +0100
Subject: HTTPSConnection from http.client?
References: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>
Message-ID: <n2f2mb$qoo$1@ger.gmane.org>

Alex Naumov wrote:

> Hello,
> 
> does anybody know how to create a HTTPS connections in python2 or python3?
> I tried second day to do that with http.client[1], but every time get
> error:
> 
> from http.client import HTTPSConnection
> ImportError: cannot import name HTTPSConnection
> 
> 
> Where is HTTPSConnection located? Which module?
> 
> I use openSUSE 13.1 x86_64.
> 
> Thank you,
> Alex
> 
> 
> [1] https://docs.python.org/3/library/http.client.html

Did you compile Python from source? You may be missing the development 
packages.

If you are using the Python provided by the distribution, perhaps support 
for SSL is in a separate package?

Note that I'm guessing, I don't have openSUSE.




From marko at pacujo.net  Tue Nov 17 06:41:23 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 17 Nov 2015 13:41:23 +0200
Subject: HTTPSConnection from http.client?
References: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>
 <mailman.382.1447759388.16136.python-list@python.org>
Message-ID: <87lh9wrgyk.fsf@elektro.pacujo.net>

Peter Otten <__peter__ at web.de>:

> Alex Naumov wrote:
>> I tried second day to do that with http.client[1], but every time get
>> error:
>> 
>> from http.client import HTTPSConnection
>> ImportError: cannot import name HTTPSConnection
>> [...]
>> I use openSUSE 13.1 x86_64.
>
> Did you compile Python from source? You may be missing the development 
> packages.
>
> If you are using the Python provided by the distribution, perhaps support 
> for SSL is in a separate package?
>
> Note that I'm guessing, I don't have openSUSE.

On a minimal SLES-12-x86_64 installation:

   $ python3
   Python 3.4.1 (default, Jun 19 2014, 14:40:48) [GCC] on linux
   Type "help", "copyright", "credits" or "license" for more information.
   >>> from http.client import HTTPSConnection
   >>> 


Marko


From alexander_naumov at opensuse.org  Tue Nov 17 07:34:56 2015
From: alexander_naumov at opensuse.org (Alex Naumov)
Date: Tue, 17 Nov 2015 13:34:56 +0100
Subject: HTTPSConnection from http.client?
In-Reply-To: <n2f2mb$qoo$1@ger.gmane.org>
References: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>
 <n2f2mb$qoo$1@ger.gmane.org>
Message-ID: <CABPy6+zTajMJ8uoPxADbs7hzhVt31XoxGg_NZtaTYwL=LDMwBw@mail.gmail.com>

On Tue, Nov 17, 2015 at 12:22 PM, Peter Otten <__peter__ at web.de> wrote:
> Alex Naumov wrote:
>
>> Hello,
>>
>> does anybody know how to create a HTTPS connections in python2 or python3?
>> I tried second day to do that with http.client[1], but every time get
>> error:
>>
>> from http.client import HTTPSConnection
>> ImportError: cannot import name HTTPSConnection
>>
>>
>> Where is HTTPSConnection located? Which module?
>>
>> I use openSUSE 13.1 x86_64.
>>
>> Thank you,
>> Alex
>>
>>
>> [1] https://docs.python.org/3/library/http.client.html
>
> Did you compile Python from source?

No, I install it as a package.

> You may be missing the development
> packages.

Yes, it looks like some packages are not there.


> On a minimal SLES-12-x86_64 installation:

Can you tell me what's the name of package with http.client module please?

Thank you,
Alex


From __peter__ at web.de  Tue Nov 17 08:24:45 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 14:24:45 +0100
Subject: HTTPSConnection from http.client?
References: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>
 <n2f2mb$qoo$1@ger.gmane.org>
 <CABPy6+zTajMJ8uoPxADbs7hzhVt31XoxGg_NZtaTYwL=LDMwBw@mail.gmail.com>
Message-ID: <n2f9qv$gv4$1@ger.gmane.org>

Alex Naumov wrote:

> On Tue, Nov 17, 2015 at 12:22 PM, Peter Otten <__peter__ at web.de> wrote:
>> Alex Naumov wrote:
>>
>>> Hello,
>>>
>>> does anybody know how to create a HTTPS connections in python2 or
>>> python3? I tried second day to do that with http.client[1], but every
>>> time get error:
>>>
>>> from http.client import HTTPSConnection
>>> ImportError: cannot import name HTTPSConnection
>>>
>>>
>>> Where is HTTPSConnection located? Which module?
>>>
>>> I use openSUSE 13.1 x86_64.
>>>
>>> Thank you,
>>> Alex
>>>
>>>
>>> [1] https://docs.python.org/3/library/http.client.html
>>
>> Did you compile Python from source?
> 
> No, I install it as a package.
> 
>> You may be missing the development
>> packages.
> 
> Yes, it looks like some packages are not there.
> 
> 
>> On a minimal SLES-12-x86_64 installation:
> 
> Can you tell me what's the name of package with http.client module please?

You already have that module as it is part of the Python standard 
installation. You can double check by importing something that is always 
available. E. g. the following should succeed on your system

>>> from http.client import HTTPConnection
>>>

What you are likely missing is ssl support. Try

>>> import ssl

to verify that it fails and post the traceback.

Unfortunately my conclusion from Marco's post is that

>>> from http.client import HTTPSConnection

should succeed on your system without the need for additional packages. 
Something seems to be broken, but I have no idea what, sorry.



From andrea.gavana at gmail.com  Tue Nov 17 08:26:49 2015
From: andrea.gavana at gmail.com (andrea.gavana at gmail.com)
Date: Tue, 17 Nov 2015 05:26:49 -0800 (PST)
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
Message-ID: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>

Hello List,

     I am working with relatively humongous binary files (created via cPickle), and I stumbled across some unexpected (for me) performance differences between two approaches I use to load those files:

1. Simply use cPickle.load(fid)

2. Read the file as binary using file.read() and then use cPickle.loads on the resulting output

In the snippet below, the MakePickle function is a dummy function that generates a relatively big binary file with cPickle (WARNING: around 3 GB) in the current directory. I am using NumPy arrays to make the file big but my original data structure is much more complicated, and things like HDF5 or databases are currently not an option - I'd like to stay with pickles.

The ReadPickle function simply uses cPickle.load(fid) on the opened binary file, and on my PC it takes about 2.3 seconds (approach 1).

The ReadPlusLoads function reads the file using file.read() and then use cPickle.loads on the resulting output (approach 2). On my PC, the file.read() process takes 15 seconds (!!!) and the cPickle.loads only 1.5 seconds.

What baffles me is the time it takes to read the file using file.read(): is there any way to slurp it all in one go (somehow) into a string ready for cPickle.loads without that much of an overhead?

Note that all of this has been done on Windows 7 64bit with Python 2.7 64bit, with 16 cores and 100 GB RAM (so memory should not be a problem).

Thank you in advance for all suggestions :-) .

Andrea.


# Begin code

import os, sys
import time
import cPickle
import numpy


class Dummy(object):

    def __init__(self, name):

        self.name = name
        self.data = numpy.random.rand(200, 600, 10)


def MakePickle():

    num_objects = 300
    list_of_objects = []

    for index in xrange(num_objects):
        dummy = Dummy('dummy_%d'%index)
        list_of_objects.append(dummy)

    fid = open('dummy.pkl', 'wb')

    start = time.time()
    out = cPickle.dumps(list_of_objects, cPickle.HIGHEST_PROTOCOL)
    end = time.time()
    print 'cPickle.dumps time:', end-start
    start = end
    fid.write(out)
    end = time.time()
    print 'file.write time:', end-start
    fid.close()


def ReadPickle():

    fid = open('dummy.pkl', 'rb')

    start = time.time()
    out = cPickle.load(fid)
    end = time.time()
    print 'cPickle.load time:', end-start
    fid.close()


def ReadPlusLoads():

    start = time.time()
    fid = open('dummy.pkl', 'rb')
    strs = fid.read()
    fid.close()
    end = time.time()
    print 'file.read time:', end-start
    start = end
    out = cPickle.loads(strs)
    end = time.time()
    print 'cPickle.loads time:', end-start


if __name__ == '__main__':
    ReadPickle()
    ReadPlusLoads()

# End code


From __peter__ at web.de  Tue Nov 17 09:14:18 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 15:14:18 +0100
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
Message-ID: <n2fcnr$1np$1@ger.gmane.org>

andrea.gavana at gmail.com wrote:

> Hello List,
> 
>      I am working with relatively humongous binary files (created via
>      cPickle), and I stumbled across some unexpected (for me) performance
>      differences between two approaches I use to load those files:
> 
> 1. Simply use cPickle.load(fid)
> 
> 2. Read the file as binary using file.read() and then use cPickle.loads on
> the resulting output
> 
> In the snippet below, the MakePickle function is a dummy function that
> generates a relatively big binary file with cPickle (WARNING: around 3 GB)
> in the current directory. I am using NumPy arrays to make the file big but
> my original data structure is much more complicated, and things like HDF5
> or databases are currently not an option - I'd like to stay with pickles.
> 
> The ReadPickle function simply uses cPickle.load(fid) on the opened binary
> file, and on my PC it takes about 2.3 seconds (approach 1).
> 
> The ReadPlusLoads function reads the file using file.read() and then use
> cPickle.loads on the resulting output (approach 2). On my PC, the
> file.read() process takes 15 seconds (!!!) and the cPickle.loads only 1.5
> seconds.
> 
> What baffles me is the time it takes to read the file using file.read():
> is there any way to slurp it all in one go (somehow) into a string ready
> for cPickle.loads without that much of an overhead?
> 
> Note that all of this has been done on Windows 7 64bit with Python 2.7
> 64bit, with 16 cores and 100 GB RAM (so memory should not be a problem).
> 
> Thank you in advance for all suggestions :-) .
> 
> Andrea.
> 
> if __name__ == '__main__':
>     ReadPickle()
>     ReadPlusLoads()

Do you get roughly the same times when you execute ReadPlusLoads() before 
ReadPIckle()?



From andrea.gavana at gmail.com  Tue Nov 17 09:20:03 2015
From: andrea.gavana at gmail.com (andrea.gavana at gmail.com)
Date: Tue, 17 Nov 2015 06:20:03 -0800 (PST)
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <mailman.387.1447769670.16136.python-list@python.org>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
Message-ID: <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>

Hi Peter,

On Tuesday, November 17, 2015 at 3:14:57 PM UTC+1, Peter Otten wrote:
> Andrea Gavana wrote:
> 
> > Hello List,
> > 
> >      I am working with relatively humongous binary files (created via
> >      cPickle), and I stumbled across some unexpected (for me) performance
> >      differences between two approaches I use to load those files:
> > 
> > 1. Simply use cPickle.load(fid)
> > 
> > 2. Read the file as binary using file.read() and then use cPickle.loads on
> > the resulting output
> > 
> > In the snippet below, the MakePickle function is a dummy function that
> > generates a relatively big binary file with cPickle (WARNING: around 3 GB)
> > in the current directory. I am using NumPy arrays to make the file big but
> > my original data structure is much more complicated, and things like HDF5
> > or databases are currently not an option - I'd like to stay with pickles.
> > 
> > The ReadPickle function simply uses cPickle.load(fid) on the opened binary
> > file, and on my PC it takes about 2.3 seconds (approach 1).
> > 
> > The ReadPlusLoads function reads the file using file.read() and then use
> > cPickle.loads on the resulting output (approach 2). On my PC, the
> > file.read() process takes 15 seconds (!!!) and the cPickle.loads only 1.5
> > seconds.
> > 
> > What baffles me is the time it takes to read the file using file.read():
> > is there any way to slurp it all in one go (somehow) into a string ready
> > for cPickle.loads without that much of an overhead?
> > 
> > Note that all of this has been done on Windows 7 64bit with Python 2.7
> > 64bit, with 16 cores and 100 GB RAM (so memory should not be a problem).
> > 
> > Thank you in advance for all suggestions :-) .
> > 
> > Andrea.
> > 
> > if __name__ == '__main__':
> >     ReadPickle()
> >     ReadPlusLoads()
> 
> Do you get roughly the same times when you execute ReadPlusLoads() before 
> ReadPIckle()?


Thank you for your answer. I do get similar timings when I swap the two functions, and specifically still 15 seconds to read the file via file.read() and 2.4 seconds (more or less as before) via cPickle.load(fid).

I thought that the order of operations might be an issue but apparently that was not the case...

Andrea.



From nicoe at altern.org  Tue Nov 17 09:27:39 2015
From: nicoe at altern.org (Nicolas =?utf-8?Q?=C3=89vrard?=)
Date: Tue, 17 Nov 2015 11:27:39 -0300
Subject: Which type should be used when testing static structure appartenance
Message-ID: <20151117142739.GC20735@localhost.localdomain>

Hello,

I saw the following retweet by Raymond Hettinger in this morning:

    https://twitter.com/sanityinc/status/666485814214287360

    Programming tip: many of those arrays and hashes in your code
    should actually be sets. Match data structures to data
    constraints!

I saw just in time because in a review I wrote something like this:

    if operator not in ('where', 'not where')

and my colleague proposed that I should use a list instead of a tuple.
But reading the mentioned tweet I tend to think that a set would be a
better choice.

What are your opinion on this issue (I realize it's not something of
the utmost importance but rather a "philosophical" question).

-- 
Nicolas ?vrard - B2CK SPRL
E-mail/Jabber: nicolas.evrard at b2ck.com
Tel: +32 472 54 46 59
Website: http://www.b2ck.com/


From gandalf at shopzeus.com  Tue Nov 17 09:45:58 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Tue, 17 Nov 2015 15:45:58 +0100
Subject: Trouble installing Python 3.5.0
In-Reply-To: <1479749727.6211494.1447708113131.JavaMail.yahoo@mail.yahoo.com>
References: <1479749727.6211494.1447708113131.JavaMail.yahoo.ref@mail.yahoo.com>
 <1479749727.6211494.1447708113131.JavaMail.yahoo@mail.yahoo.com>
Message-ID: <564B3DA6.5080401@shopzeus.com>



> Hello,
>
> I installed 3.5, "successfully" as the installer indicated, yet the program wouldn't run, with the following error message: "...failed to start because api-ms-win-crt-runtime-I1-1-0.dll was not found. Re-installing the application may fix this problem." I reinstalled, but no luck. 
I think Vista and XP was supported up to Python 3.4. The newest Python
3.5 does not support Vista or XP.



From gandalf at shopzeus.com  Tue Nov 17 09:51:45 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Tue, 17 Nov 2015 15:51:45 +0100
Subject: Trouble installing Python 3.5.0
In-Reply-To: <564B3DA6.5080401@shopzeus.com>
References: <1479749727.6211494.1447708113131.JavaMail.yahoo.ref@mail.yahoo.com>
 <1479749727.6211494.1447708113131.JavaMail.yahoo@mail.yahoo.com>
 <564B3DA6.5080401@shopzeus.com>
Message-ID: <564B3F01.2000901@shopzeus.com>


>> Hello,
>>
>> I installed 3.5, "successfully" as the installer indicated, yet the program wouldn't run, with the following error message: "...failed to start because api-ms-win-crt-runtime-I1-1-0.dll was not found. Re-installing the application may fix this problem." I reinstalled, but no luck. 
> I think Vista and XP was supported up to Python 3.4. The newest Python
> 3.5 does not support Vista or XP.
https://docs.python.org/3.5/whatsnew/3.5.html

You will find this under "Unsupported Operating Systems" section.
Although Vista is not mentioned there, but Python 3.5 is built with
Microsoft Visual Studio 2015, and its runtime library is AFAIK does not
work under Vista.



From rosuav at gmail.com  Tue Nov 17 10:20:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 18 Nov 2015 02:20:04 +1100
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
Message-ID: <CAPTjJmrwpLh0-FJPq3-TOsP_14ARD5vY7qPyReJ++rDKgtTRXg@mail.gmail.com>

On Wed, Nov 18, 2015 at 1:20 AM,  <andrea.gavana at gmail.com> wrote:
> Thank you for your answer. I do get similar timings when I swap the two functions, and specifically still 15 seconds to read the file via file.read() and 2.4 seconds (more or less as before) via cPickle.load(fid).
>
> I thought that the order of operations might be an issue but apparently that was not the case...

What if you call one of them twice and then the other? Just trying to
rule out any possibility that it's a caching problem.

On my Linux box, running 2.7.9 64-bit, the two operations take roughly
the same amount of time (1.8 seconds for load vs 1s to read and 0.8 to
loads). Are you able to run this off a RAM disk or something?

Most curious.

ChrisA


From rosuav at gmail.com  Tue Nov 17 10:28:31 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 18 Nov 2015 02:28:31 +1100
Subject: Which type should be used when testing static structure
 appartenance
In-Reply-To: <20151117142739.GC20735@localhost.localdomain>
References: <20151117142739.GC20735@localhost.localdomain>
Message-ID: <CAPTjJmrbCCoQ+wAcPbk8QQneFrEyHgxqNc6bKPmZCQorgQOd+g@mail.gmail.com>

On Wed, Nov 18, 2015 at 1:27 AM, Nicolas ?vrard <nicoe at altern.org> wrote:
> I saw just in time because in a review I wrote something like this:
>
>    if operator not in ('where', 'not where')
>
> and my colleague proposed that I should use a list instead of a tuple.
> But reading the mentioned tweet I tend to think that a set would be a
> better choice.
>
> What are your opinion on this issue (I realize it's not something of
> the utmost importance but rather a "philosophical" question).

Definitely a set. I don't know why it would be better to use a list;
there's no advantage here for the list. "x [not] in some_set"
accurately represents the concept of "any of these will match". With a
two-element list/tuple/set, I doubt there's going to be any
significant performance difference, but if anything, I would expect
the tuple to be the fastest (because it can be stored as a literal),
and the other two need to be built; but CPython's optimizer has me
beat there - they're all stored as literals (the list becomes a tuple,
the set becomes a frozenset), meaning there's basically no difference.
So you're free to use the one that expresses the concept of "is this
part of this set of strings", which is the set.

ChrisA


From andrea.gavana at gmail.com  Tue Nov 17 10:31:50 2015
From: andrea.gavana at gmail.com (andrea.gavana at gmail.com)
Date: Tue, 17 Nov 2015 07:31:50 -0800 (PST)
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <mailman.392.1447773612.16136.python-list@python.org>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
Message-ID: <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>

Hi Chris,

On Tuesday, November 17, 2015 at 4:20:34 PM UTC+1, Chris Angelico wrote:
> On Wed, Nov 18, 2015 at 1:20 AM,  Andrea Gavana wrote:
> > Thank you for your answer. I do get similar timings when I swap the two functions, and specifically still 15 seconds to read the file via file.read() and 2.4 seconds (more or less as before) via cPickle.load(fid).
> >
> > I thought that the order of operations might be an issue but apparently that was not the case...
> 
> What if you call one of them twice and then the other? Just trying to
> rule out any possibility that it's a caching problem.
> 
> On my Linux box, running 2.7.9 64-bit, the two operations take roughly
> the same amount of time (1.8 seconds for load vs 1s to read and 0.8 to
> loads). Are you able to run this off a RAM disk or something?
> 
> Most curious.


Thank you for taking the time to run my little script. I have now run it with multiple combinations of calls (twice the first then the other, then viceversa, then alternate between the two functions multiple times, then three times the second and once the first, ...) with no luck at all.

The file.read() line of code takes always at minimum 14 seconds (in all the trials I have done), while the cPickle.load call ranges between 2.3 and 2.5 seconds.

I am puzzled with no end... Might there be something funny with my C libraries that use fread? I'm just shooting in the dark. I have a standard Python installation on Windows, nothing fancy :-( 

Andrea.


From alexander_naumov at opensuse.org  Tue Nov 17 10:47:05 2015
From: alexander_naumov at opensuse.org (Alex Naumov)
Date: Tue, 17 Nov 2015 16:47:05 +0100
Subject: HTTPSConnection from http.client?
In-Reply-To: <n2f9qv$gv4$1@ger.gmane.org>
References: <CABPy6+zYvqmOFy7aMNMH0DtUNaaJ3M3nR47QPhDPijsvN2jHbA@mail.gmail.com>
 <n2f2mb$qoo$1@ger.gmane.org>
 <CABPy6+zTajMJ8uoPxADbs7hzhVt31XoxGg_NZtaTYwL=LDMwBw@mail.gmail.com>
 <n2f9qv$gv4$1@ger.gmane.org>
Message-ID: <CABPy6+wsb3nUGMMOgRkxDBBNNdxQGV_qF2hk+d32ZmKB6ZY0GQ@mail.gmail.com>

Hello Peter,

thanks for your reply.

>>> import ssl

Works well in python2 and 3.

Maybe somebody know another way to create a SSL connection (username/password)?
I just need to log in and log out.

Thanks,
Alex

On Tue, Nov 17, 2015 at 2:24 PM, Peter Otten <__peter__ at web.de> wrote:
> Alex Naumov wrote:
>
>> On Tue, Nov 17, 2015 at 12:22 PM, Peter Otten <__peter__ at web.de> wrote:
>>> Alex Naumov wrote:
>>>
>>>> Hello,
>>>>
>>>> does anybody know how to create a HTTPS connections in python2 or
>>>> python3? I tried second day to do that with http.client[1], but every
>>>> time get error:
>>>>
>>>> from http.client import HTTPSConnection
>>>> ImportError: cannot import name HTTPSConnection
>>>>
>>>>
>>>> Where is HTTPSConnection located? Which module?
>>>>
>>>> I use openSUSE 13.1 x86_64.
>>>>
>>>> Thank you,
>>>> Alex
>>>>
>>>>
>>>> [1] https://docs.python.org/3/library/http.client.html
>>>
>>> Did you compile Python from source?
>>
>> No, I install it as a package.
>>
>>> You may be missing the development
>>> packages.
>>
>> Yes, it looks like some packages are not there.
>>
>>
>>> On a minimal SLES-12-x86_64 installation:
>>
>> Can you tell me what's the name of package with http.client module please?
>
> You already have that module as it is part of the Python standard
> installation. You can double check by importing something that is always
> available. E. g. the following should succeed on your system
>
>>>> from http.client import HTTPConnection
>>>>
>
> What you are likely missing is ssl support. Try
>
>>>> import ssl
>
> to verify that it fails and post the traceback.
>
> Unfortunately my conclusion from Marco's post is that
>
>>>> from http.client import HTTPSConnection
>
> should succeed on your system without the need for additional packages.
> Something seems to be broken, but I have no idea what, sorry.
>
> --
> https://mail.python.org/mailman/listinfo/python-list


From __peter__ at web.de  Tue Nov 17 10:57:28 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 16:57:28 +0100
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
 <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>
Message-ID: <n2fip9$ajg$1@ger.gmane.org>

andrea.gavana at gmail.com wrote:

> Hi Chris,
> 
> On Tuesday, November 17, 2015 at 4:20:34 PM UTC+1, Chris Angelico wrote:
>> On Wed, Nov 18, 2015 at 1:20 AM,  Andrea Gavana wrote:
>> > Thank you for your answer. I do get similar timings when I swap the two
>> > functions, and specifically still 15 seconds to read the file via
>> > file.read() and 2.4 seconds (more or less as before) via
>> > cPickle.load(fid).
>> >
>> > I thought that the order of operations might be an issue but apparently
>> > that was not the case...
>> 
>> What if you call one of them twice and then the other? Just trying to
>> rule out any possibility that it's a caching problem.
>> 
>> On my Linux box, running 2.7.9 64-bit, the two operations take roughly
>> the same amount of time (1.8 seconds for load vs 1s to read and 0.8 to
>> loads). Are you able to run this off a RAM disk or something?
>> 
>> Most curious.
> 
> 
> Thank you for taking the time to run my little script. I have now run it
> with multiple combinations of calls (twice the first then the other, then
> viceversa, then alternate between the two functions multiple times, then
> three times the second and once the first, ...) with no luck at all.
> 
> The file.read() line of code takes always at minimum 14 seconds (in all
> the trials I have done), while the cPickle.load call ranges between 2.3
> and 2.5 seconds.
> 
> I am puzzled with no end... Might there be something funny with my C
> libraries that use fread? I'm just shooting in the dark. I have a standard
> Python installation on Windows, nothing fancy :-(

Perhaps there is a size threshold? You could experiment with different block 
sizes in the following f.read() replacement:

def read_chunked(f, size=2**20):
    read = functools.partial(f.read, size)
    return "".join(iter(read, ""))



From oscar.j.benjamin at gmail.com  Tue Nov 17 11:15:37 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 17 Nov 2015 16:15:37 +0000
Subject: Which type should be used when testing static structure
 appartenance
In-Reply-To: <20151117142739.GC20735@localhost.localdomain>
References: <20151117142739.GC20735@localhost.localdomain>
Message-ID: <CAHVvXxRiUcRYnd62qOCn5dmZXUxb_w05dpTgifFNA7qwB6Dn+g@mail.gmail.com>

On 17 November 2015 at 14:27, Nicolas ?vrard <nicoe at altern.org> wrote:
> Hello,
>
> I saw the following retweet by Raymond Hettinger in this morning:
>
>    https://twitter.com/sanityinc/status/666485814214287360
>
>    Programming tip: many of those arrays and hashes in your code
>    should actually be sets. Match data structures to data
>    constraints!
>
> I saw just in time because in a review I wrote something like this:
>
>    if operator not in ('where', 'not where')
>
> and my colleague proposed that I should use a list instead of a tuple.
> But reading the mentioned tweet I tend to think that a set would be a
> better choice.
>
> What are your opinion on this issue (I realize it's not something of
> the utmost importance but rather a "philosophical" question).

Conceptually it should be a set. Really it makes little difference though.

I think that what the tip is really referring to is a situation where
you have a larger data structure. For example asking if x in y has
different algorithmic performance when y is a large tuple/list than a
set. This is because a set is a hash-table with O(1) average lookup
cost and a tuple/list needs to be scanned linearly having O(N) average
cost. This can be very costly and can often be seen in beginner code
where someone does something like:

   for x in stuff:
       if x in alist:
           # do stuff

Here the "in" operator loops over alist once for each item in stuff
(until it finds a match). If there are M things in stuff and N things
in alist then this is O(M*N) items to compare. If we convert alist to
a set at the start of the loop then we have:

    aset = set(alist)
    for xin stuff:
        if x in aset:
            # do stuff

Here the set constructor scans alist which is O(N) and then for each
of M things in stuff we do an O(1) lookup in aset. So the result is
O(M+N) meaning linear rather than quadratic performance. This can be a
significant difference especially for something so trivially easy to
do.

--
Oscar


From zachary.ware+pylist at gmail.com  Tue Nov 17 11:25:08 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Tue, 17 Nov 2015 10:25:08 -0600
Subject: Trouble installing Python 3.5.0
In-Reply-To: <564B3F01.2000901@shopzeus.com>
References: <1479749727.6211494.1447708113131.JavaMail.yahoo.ref@mail.yahoo.com>
 <1479749727.6211494.1447708113131.JavaMail.yahoo@mail.yahoo.com>
 <564B3DA6.5080401@shopzeus.com> <564B3F01.2000901@shopzeus.com>
Message-ID: <CAKJDb-M+R6=yM+Ek2S59SW78BdygsFKO-LF=6-tvFoNowOTcRw@mail.gmail.com>

On Tue, Nov 17, 2015 at 8:51 AM, Nagy L?szl? Zsolt <gandalf at shopzeus.com> wrote:
> I think Vista and XP was supported up to Python 3.4. The newest Python
> 3.5 does not support Vista or XP.

Vista is still supported in Python 3.5, but it requires the Universal
CRT update, which requires the latest Service Pack for Vista (see
here: https://support.microsoft.com/en-us/kb/2999226).  If your Vista
is up to date, you should have no problem.

It could be argued that if you're not up to date you're not supported
by Microsoft and thus not supported by Python, but that may be
stretching things a bit.

-- 
Zach


From rxjwg98 at gmail.com  Tue Nov 17 11:31:08 2015
From: rxjwg98 at gmail.com (fl)
Date: Tue, 17 Nov 2015 08:31:08 -0800 (PST)
Subject: Help on savefig parameters
Message-ID: <38fcc7ab-409d-4050-9058-634d987bcdd8@googlegroups.com>

Hi,
I find the parameters of savefig function has the similar format of that of
main(*argc, **argv) in C. I have tried with savefig("temp.pdf", format='pdf'),
and it works. I get the help content of savefig() as below.
But I cannot understand why they also give: 

savefig(fname, dpi=None, facecolor='w', edgecolor='w', ...

For me, it looks like the first item, i.e. 'args' is missing.
Could you explain it to me?

Thanks,

////////////////
savefig(*args, **kwargs)
    Save the current figure.
    
    Call signature::
    
      savefig(fname, dpi=None, facecolor='w', edgecolor='w',
              orientation='portrait', papertype=None, format=None,
              transparent=False, bbox_inches=None, pad_inches=0.1,
              frameon=None)


From andrea.gavana at gmail.com  Tue Nov 17 11:31:41 2015
From: andrea.gavana at gmail.com (andrea.gavana at gmail.com)
Date: Tue, 17 Nov 2015 08:31:41 -0800 (PST)
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <mailman.395.1447775861.16136.python-list@python.org>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
 <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>
 <mailman.395.1447775861.16136.python-list@python.org>
Message-ID: <f9a98231-e6df-4557-8ca1-20d9644825ca@googlegroups.com>

Hi Peter,

On Tuesday, November 17, 2015 at 4:57:57 PM UTC+1, Peter Otten wrote:
> Andrea Gavana wrote:
> 
> > Hi Chris,
> > 
> > On Tuesday, November 17, 2015 at 4:20:34 PM UTC+1, Chris Angelico wrote:
> >> On Wed, Nov 18, 2015 at 1:20 AM,  Andrea Gavana wrote:
> >> > Thank you for your answer. I do get similar timings when I swap the two
> >> > functions, and specifically still 15 seconds to read the file via
> >> > file.read() and 2.4 seconds (more or less as before) via
> >> > cPickle.load(fid).
> >> >
> >> > I thought that the order of operations might be an issue but apparently
> >> > that was not the case...
> >> 
> >> What if you call one of them twice and then the other? Just trying to
> >> rule out any possibility that it's a caching problem.
> >> 
> >> On my Linux box, running 2.7.9 64-bit, the two operations take roughly
> >> the same amount of time (1.8 seconds for load vs 1s to read and 0.8 to
> >> loads). Are you able to run this off a RAM disk or something?
> >> 
> >> Most curious.
> > 
> > 
> > Thank you for taking the time to run my little script. I have now run it
> > with multiple combinations of calls (twice the first then the other, then
> > viceversa, then alternate between the two functions multiple times, then
> > three times the second and once the first, ...) with no luck at all.
> > 
> > The file.read() line of code takes always at minimum 14 seconds (in all
> > the trials I have done), while the cPickle.load call ranges between 2.3
> > and 2.5 seconds.
> > 
> > I am puzzled with no end... Might there be something funny with my C
> > libraries that use fread? I'm just shooting in the dark. I have a standard
> > Python installation on Windows, nothing fancy :-(
> 
> Perhaps there is a size threshold? You could experiment with different block 
> sizes in the following f.read() replacement:
> 
> def read_chunked(f, size=2**20):
>     read = functools.partial(f.read, size)
>     return "".join(iter(read, ""))


Thank you for the suggestion. I have used the read_chunked function in my experiments now and I can report a nice improvements - I have tried various chunk sizes, from 2**10 to 2**31-1, and in general the optimum lies around size=2**22, although it is essentially flat from 2**20 up to 2**30 - with some interesting spikes at 45 seconds for 2**14 and 2**15 (see table below).

Using your suggestion, I got it down to 3.4 seconds (on average). Still at least twice slower than cPickle.load, but better. 

What I find most puzzling is that a pure file.read() (or your read_chunked variation) should normally be much faster than a cPickle.load (which does so many more things than just reading a file), shouldn't it?


Timing table:

Size (power of 2)	Read Time (seconds)
10	9.14
11	8.59
12	7.67
13	5.70
14	46.06
15	45.00
16	24.80
17	14.23
18	8.95
19	5.58
20	3.41
21	3.39
22	3.34
23	3.39
24	3.39
25	3.42
26	3.43
27	3.44
28	3.48
29	3.59
30	3.72



From rgaddi at technologyhighland.invalid  Tue Nov 17 11:39:15 2015
From: rgaddi at technologyhighland.invalid (Rob Gaddi)
Date: Tue, 17 Nov 2015 16:39:15 -0000 (UTC)
Subject: Help on savefig parameters
References: <38fcc7ab-409d-4050-9058-634d987bcdd8@googlegroups.com>
Message-ID: <n2fl7j$bbq$1@dont-email.me>

On Tue, 17 Nov 2015 08:31:08 -0800, fl wrote:

> Hi,
> I find the parameters of savefig function has the similar format of that
> of main(*argc, **argv) in C. I have tried with savefig("temp.pdf",
> format='pdf'),
> and it works. I get the help content of savefig() as below.
> But I cannot understand why they also give:
> 
> savefig(fname, dpi=None, facecolor='w', edgecolor='w', ...
> 
> For me, it looks like the first item, i.e. 'args' is missing.
> Could you explain it to me?
> 
> Thanks,
> 
> ////////////////
> savefig(*args, **kwargs)
>     Save the current figure.
>     
>     Call signature::
>     
>       savefig(fname, dpi=None, facecolor='w', edgecolor='w',
>               orientation='portrait', papertype=None, format=None,
>               transparent=False, bbox_inches=None, pad_inches=0.1,
>               frameon=None)

Numpy/scipy/matplotlib are in large part autogenerated code from the 
underlying libraries; that's where the default *args, **kwargs arguments 
are coming from.  The signature given in the documentation is the one 
that actually matters.

Prefer the web documentation to the inline docs for that entire set of 
libraries; it'll make your life easier.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.


From __peter__ at web.de  Tue Nov 17 12:20:44 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 17 Nov 2015 18:20:44 +0100
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
 <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>
 <mailman.395.1447775861.16136.python-list@python.org>
 <f9a98231-e6df-4557-8ca1-20d9644825ca@googlegroups.com>
Message-ID: <n2fnle$r7$1@ger.gmane.org>

andrea.gavana at gmail.com wrote:

>> > I am puzzled with no end... Might there be something funny with my C
>> > libraries that use fread? I'm just shooting in the dark. I have a
>> > standard Python installation on Windows, nothing fancy :-(
>> 
>> Perhaps there is a size threshold? You could experiment with different
>> block sizes in the following f.read() replacement:
>> 
>> def read_chunked(f, size=2**20):
>>     read = functools.partial(f.read, size)
>>     return "".join(iter(read, ""))
> 
> 
> Thank you for the suggestion. I have used the read_chunked function in my
> experiments now and I can report a nice improvements - I have tried
> various chunk sizes, from 2**10 to 2**31-1, and in general the optimum
> lies around size=2**22, although it is essentially flat from 2**20 up to
> 2**30 - with some interesting spikes at 45 seconds for 2**14 and 2**15
> (see table below).
> 
> Using your suggestion, I got it down to 3.4 seconds (on average). Still at
> least twice slower than cPickle.load, but better.
> 
> What I find most puzzling is that a pure file.read() (or your read_chunked
> variation) should normally be much faster than a cPickle.load (which does
> so many more things than just reading a file), shouldn't it?

That would have been my expectation, too. 

I had a quick look into the fileobject.c source and didn't see anything that 
struck me as suspicious.

I think you should file a bug report so that an expert can check if there is 
an underlying problem in Python or if it is a matter of the OS. 

> Timing table:
> 
> Size (power of 2)	Read Time (seconds)
> 10	9.14
> 11	8.59
> 12	7.67
> 13	5.70
> 14	46.06
> 15	45.00
> 16	24.80
> 17	14.23
> 18	8.95
> 19	5.58
> 20	3.41
> 21	3.39
> 22	3.34
> 23	3.39
> 24	3.39
> 25	3.42
> 26	3.43
> 27	3.44
> 28	3.48
> 29	3.59
> 30	3.72




From ian.g.kelly at gmail.com  Tue Nov 17 12:49:00 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 17 Nov 2015 10:49:00 -0700
Subject: PEP 484 stubs with generic types
Message-ID: <CALwzidkRSaLnh8pDioJC7pqdzOEw=2BBRZNyN=0HsLyCsZXz=w@mail.gmail.com>

Playing around a bit with PEP 484, I annotated a function that returns
an asyncio.Future:

import asyncio

def get_future() -> asyncio.Future[int]:
    future = asyncio.Future()
    future.set_result(42)
    return future

The problem with this is that in Python 3.5, asyncio.Future can't be
used as a generic type. Fortunately, the typeshed repository provides
a stub that defines it as a generic type:

https://github.com/python/typeshed/blob/master/stdlib/3.4/asyncio/futures.pyi

This is fine for running a static type checker, but it still creates a
problem when actually running the code. The real asyncio.Future
doesn't support indexing, and so the annotation causes a TypeError at
runtime.

I could write the annotation as a forward reference, avoiding the TypeError:

def get_future() -> "asyncio.Future[int]":
    ...

But PEP 484 stipulates that a forward reference "should evaluate
without errors once the module has been fully loaded", so this is
invalid.

Is there any advice for this case? How are generic types meant to be
used with stub files?


From rxjwg98 at gmail.com  Tue Nov 17 15:51:12 2015
From: rxjwg98 at gmail.com (fl)
Date: Tue, 17 Nov 2015 12:51:12 -0800 (PST)
Subject: Is there any reason to introduce this intermediate variable (sz)?
Message-ID: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>

Hi,

I find the following code snippet, which is useful in my project:


n_iter = 50
sz = (n_iter,) # size of array
x = -0.37727 
z = np.random.normal(x,0.1,size=sz) 

Q = 1e-5 # process variance

# allocate space for arrays
xhat=np.zeros(sz)      
P=np.zeros(sz)         


I learn Python now and the above code seems from an experienced author.
The curious thing to me is the variable 'sz'. I have check np.zeros(shape, ..)

shape : int or sequence of ints


The introduced 'sz' is a tuple. If n_iter function is similar to a constant
in C, I don't see the reason for 'sz'. In fact, 'n_iter' is an int, which fits
the below 

np.zeros(shape)

correctly. Could you see something useful with variable 'sz'?

Thanks,


From gordon at panix.com  Tue Nov 17 16:02:33 2015
From: gordon at panix.com (John Gordon)
Date: Tue, 17 Nov 2015 21:02:33 +0000 (UTC)
Subject: Is there any reason to introduce this intermediate variable (sz)?
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
Message-ID: <n2g4l9$dqh$1@reader1.panix.com>

In <bad9ac66-38aa-4445-a486-6df0e9c7752c at googlegroups.com> fl <rxjwg98 at gmail.com> writes:

> correctly. Could you see something useful with variable 'sz'?

'sz' is fewer characters than '(n_iter,)', which may make your code easier
to read.

The np.zeros() function explicitly accepts an 'int or sequence of ints',
so you don't specifically need a sequence.  Is the same true for the
'size' keyword argument of np.random.normal()?

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From rxjwg98 at gmail.com  Tue Nov 17 16:27:22 2015
From: rxjwg98 at gmail.com (fl)
Date: Tue, 17 Nov 2015 13:27:22 -0800 (PST)
Subject: Is there any reason to introduce this intermediate variable (sz)?
In-Reply-To: <n2g4l9$dqh$1@reader1.panix.com>
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
 <n2g4l9$dqh$1@reader1.panix.com>
Message-ID: <c9b5f60f-b1ec-4857-bb02-2748a28b5460@googlegroups.com>

On Tuesday, November 17, 2015 at 4:03:05 PM UTC-5, John Gordon wrote:
> In <bad9ac66-38aa-4445-a486-6df0e9c7752c at googlegroups.com> fl <@gmail.com> writes:
> 
> > correctly. Could you see something useful with variable 'sz'?
> 
> 'sz' is fewer characters than '(n_iter,)', which may make your code easier
> to read.
> 
> The np.zeros() function explicitly accepts an 'int or sequence of ints',
> so you don't specifically need a sequence.  Is the same true for the
> 'size' keyword argument of np.random.normal()?
> 
> -- 
> John Gordon                   A is for Amy, who fell down the stairs
> @panix.com              B is for Basil, assaulted by bears
>                                 -- Edward Gorey, "The Gashlycrumb Tinies"

Hi, I get the following for the third parameter of np.random.normal():
size : int or tuple of ints, optional

I still don't see the necessity of 'sz'. Thanks,


From gordon at panix.com  Tue Nov 17 17:20:39 2015
From: gordon at panix.com (John Gordon)
Date: Tue, 17 Nov 2015 22:20:39 +0000 (UTC)
Subject: Is there any reason to introduce this intermediate variable (sz)?
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
 <n2g4l9$dqh$1@reader1.panix.com>
 <c9b5f60f-b1ec-4857-bb02-2748a28b5460@googlegroups.com>
Message-ID: <n2g97m$qf6$1@reader1.panix.com>

In <c9b5f60f-b1ec-4857-bb02-2748a28b5460 at googlegroups.com> fl <rxjwg98 at gmail.com> writes:

> I still don't see the necessity of 'sz'. Thanks,

sz isn't required.  You can use (n_iter,) in place of sz.

However, as I posted earlier, sz is shorter so it might make your code
easier to read.

Using sz can also lead to easier code maintenance.  If the contents of
the tuple were ever to change, it would be much easier to simply change
it in once place (the definition of sz), rather than having to edit
several different occurrences of (n_iter,) in your code.


-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From breamoreboy at yahoo.co.uk  Tue Nov 17 17:33:34 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 17 Nov 2015 22:33:34 +0000
Subject: Is there any reason to introduce this intermediate variable (sz)?
In-Reply-To: <c9b5f60f-b1ec-4857-bb02-2748a28b5460@googlegroups.com>
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
 <n2g4l9$dqh$1@reader1.panix.com>
 <c9b5f60f-b1ec-4857-bb02-2748a28b5460@googlegroups.com>
Message-ID: <n2ga0g$gso$1@ger.gmane.org>

On 17/11/2015 21:27, fl wrote:
> On Tuesday, November 17, 2015 at 4:03:05 PM UTC-5, John Gordon wrote:
>> In <bad9ac66-38aa-4445-a486-6df0e9c7752c at googlegroups.com> fl <@gmail.com> writes:
>>
>>> correctly. Could you see something useful with variable 'sz'?
>>
>> 'sz' is fewer characters than '(n_iter,)', which may make your code easier
>> to read.
>>
>> The np.zeros() function explicitly accepts an 'int or sequence of ints',
>> so you don't specifically need a sequence.  Is the same true for the
>> 'size' keyword argument of np.random.normal()?
>>
>> --
>> John Gordon                   A is for Amy, who fell down the stairs
>> @panix.com              B is for Basil, assaulted by bears
>>                                  -- Edward Gorey, "The Gashlycrumb Tinies"
>
> Hi, I get the following for the third parameter of np.random.normal():
> size : int or tuple of ints, optional
>
> I still don't see the necessity of 'sz'. Thanks,
>

I don't see the necessity for you to bombard this list with question 
after question without bothering to try and provide your own answers 
first.  Did your last skivvy die of overwork?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From stephane at wirtel.be  Tue Nov 17 22:29:03 2015
From: stephane at wirtel.be (Stephane Wirtel)
Date: Wed, 18 Nov 2015 04:29:03 +0100
Subject: Mapping between python packages and distro packages?
Message-ID: <20151118032903.GA8040@sg1>


Hi,

Do you know if there is a library to match a python package (from PyPI)
and find the right debian/redhat packages ?

Thank you,

Stephane
-- 
St?phane Wirtel - http://wirtel.be - @matrixise


From ben+python at benfinney.id.au  Tue Nov 17 23:33:08 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 18 Nov 2015 15:33:08 +1100
Subject: Mapping between python packages and distro packages?
References: <20151118032903.GA8040@sg1>
Message-ID: <85vb90c4fv.fsf@benfinney.id.au>

Stephane Wirtel <stephane at wirtel.be> writes:

> Do you know if there is a library to match a python package (from PyPI)
> and find the right debian/redhat packages ?

What would count as ?the right package??

Do you mean ?the package that has that PyPI distribution URL in its
?debian/watch? configuration??

Do you mean ?the package that names that PyPI distribution in its
?debian/copyright? ?Source? field??

Or something else?

The answers will differ depending on exactly what question is being
asked of the data.

If you can define exactly what query you want to perform, perhaps a
solution can be offered.

-- 
 \     ?The Vatican is not a state.? a state must have territory. This |
  `\         is a palace with gardens, about as big as an average golf |
_o__)                         course.? ?Geoffrey Robertson, 2010-09-18 |
Ben Finney



From hua_lin at live.cn  Tue Nov 17 23:58:30 2015
From: hua_lin at live.cn (=?gb2312?B?z8S7qsHW?=)
Date: Wed, 18 Nov 2015 04:58:30 +0000
Subject: how do I learn python ?
Message-ID: <BLU177-W25FC22D76121842F28AC97871C0@phx.gbl>

 		 	   		  

From rosuav at gmail.com  Wed Nov 18 01:44:51 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 18 Nov 2015 17:44:51 +1100
Subject: Mapping between python packages and distro packages?
In-Reply-To: <85vb90c4fv.fsf@benfinney.id.au>
References: <20151118032903.GA8040@sg1>
	<85vb90c4fv.fsf@benfinney.id.au>
Message-ID: <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>

On Wed, Nov 18, 2015 at 3:33 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> What would count as ?the right package??
>
> Do you mean ?the package that has that PyPI distribution URL in its
> ?debian/watch? configuration??
>
> Do you mean ?the package that names that PyPI distribution in its
> ?debian/copyright? ?Source? field??
>
> Or something else?

I don't know how the program would detect it, but I'd be thinking "the
one where 'sudo apt-get install PACKAGENAME' gets the same code that
'pip install THING' gets". In a lot of cases, PACKAGENAME will simply
be python-THING or python3-THING, eg python3-sqlalchemy,
python3-scipy, python3-bs4; as a human, that's what I'd try first. But
having a program recognize this would be hugely beneficial.

ChrisA


From dh at dotcom.mfs32  Wed Nov 18 02:50:30 2015
From: dh at dotcom.mfs32 (Daniel Haude)
Date: 18 Nov 2015 07:50:30 GMT
Subject: Writing SOME class methods in C
Message-ID: <slrnn4obfa.db7.dh@dotcom.mfs32>

Hello,

I'm trying to implement some (but not all) methods of a Python class in C.
What I've found on the Net is:
 - how to implement entire modules in C so that I can import that module and
   use the C functions (successfully done it, too).
 - how to implement entire classes in C

But I can't find any examples of modules which consist of a mixture of C and
Python, nor modules that define classes of which some members are
implemented in C, others in Python. Of course, once I have the "mixture" bit
figured out I could just define wrapper class methods that call C functions
(functions impleneted in C, that is). But I would find it rather elegant if
the C function could access the class members directly. The fact that the
C extension functions have a mandatory "PyObject *self" parameter tells me
that this must be somehow possible, but I don't know how.

I'm sure that many of the plethora of Python extension modules out there
must use the technique that I'm looking for, but I don't even know where to
start looking. Pointers are welcome.

Thanks,
robert




From df at see.replyto.invalid  Wed Nov 18 03:05:37 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Wed, 18 Nov 2015 08:05:37 +0000
Subject: Is there any reason to introduce this intermediate variable (sz)?
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
Message-ID: <auao4btnismb7i1r1fi8tpi8f2s1asvmig@4ax.com>

fl <rxjwg98 at gmail.com> wrote:

>Hi,
>I find the following code snippet, which is useful in my project:
> ...
>correctly. Could you see something useful with variable 'sz'?

So that's example code in "An Introduction to the Kalman Filter" by Greg
Welch and Gary Bishop, and no, that construct was unnecessary. As you've
figured out, you can use the integer directly.

It's the usual problem that people get when they switch from using
Octave/Matlab to numpy/scipy/matplotlib. The former are better in an
interactive maths-oriented environment, but people then often then
switch to Python for more complex algorithms to take advantage of the
features of an advanced general-purpose programming language. The
problem that people then run into is that although there are equivalents
in the Python libraries for most of the Matlab functions, this happens
to be an area where the documentation is particularly uneven.

"Pylab" is a project that attempted to be a Python equivalent of Matlab,
but has now become a depreciated appendix to matplotlib. There have been
attempts to restart it as a feature of Ipython, but although it mostly
works, the documentation is almost nonexistent. The only way to figure
out what it can do is to try it yourself with a lot of trial and error.

Anyway, don't be surprised if you see unnecessary elaborations in
maths/science Python code because it's what you expect when people are
arriving at code that works from reading poor documentation, trial and
error, and Googling other peoples code snippets. Just try it yourself
and save yourself time rather than asking for hand-holding.


From v+python at g.nevcal.com  Wed Nov 18 03:12:35 2015
From: v+python at g.nevcal.com (Glenn Linderman)
Date: Wed, 18 Nov 2015 00:12:35 -0800
Subject: Launcher, and ftype Python.File
Message-ID: <564C32F3.2070909@g.nevcal.com>

Setting up a new machine with Windows 10, I installed Python 3.5.0 and 
the Launcher. Invoking python files from batch files as

foo.py -a -bunch -of -parameters

Didn't seem to do _anything_ so I checked:

d:\>assoc .py
.py=Python.File

d:\>ftype Python.File
Python.File="C:\Windows\py.exe" "%L" %*

I'm surprised by the "%L" where usually programs have "%1". Is this a 
new Windows feature I don't know about yet, or is it a bug in the 
installer for the Launcher?

ftype /?  does not enlighten me that there is a new %L feature available.


I did upgrade to Threshold 2 after installing Python and before using 
it, if that matters, just due to the timing of setting up the new machine.

Turns out I had an empty file named foo.py and that is why it didn't do 
anything, but now I'm just really puzzled about what "%L" means... 
Google doesn't support searching for "%L" very well.


From framstag at rus.uni-stuttgart.de  Wed Nov 18 03:39:19 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 08:39:19 +0000 (UTC)
Subject: non-blocking getkey?
Message-ID: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>

In my program (for python 2.7) the user must enter file names with
mouse copy+paste. I use:

while True:
  file = raw_input(prompt)
  if file == '': break
  files.append(file)
      
The problem now is: my users do not hit ENTER after pasting.
The file names are pasted together in one single line without space or
other delimiter.

My idea now is: instead of raw_input() I use a get_paste() function, which
reads input character for input character and after a (say) 1 s timeout it
returns the string. Pasting a string with the mouse is rather fast, there
should be no big delay between the characters.

How can I implement such a get_paste() function?
I need a non-blocking getkey() function.

It must work on Windows and Linux.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From gandalf at shopzeus.com  Wed Nov 18 04:00:21 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Wed, 18 Nov 2015 10:00:21 +0100
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <n2fip9$ajg$1@ger.gmane.org>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
 <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>
 <n2fip9$ajg$1@ger.gmane.org>
Message-ID: <564C3E25.5090900@shopzeus.com>


> Perhaps there is a size threshold? You could experiment with different block 
> sizes in the following f.read() replacement:
>
> def read_chunked(f, size=2**20):
>     read = functools.partial(f.read, size)
>     return "".join(iter(read, ""))
>
Under win32 platform, my experience is that the fastest way to read
binary file from disk is the mmap module. You should try that too.


From auriocus at gmx.de  Wed Nov 18 04:14:45 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 18 Nov 2015 10:14:45 +0100
Subject: non-blocking getkey?
In-Reply-To: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n2hfe1$n3l$1@dont-email.me>

Am 18.11.15 um 09:39 schrieb Ulli Horlacher:
> In my program (for python 2.7) the user must enter file names with
> mouse copy+paste. I use:
>
> while True:
>    file = raw_input(prompt)
>    if file == '': break
>    files.append(file)
>
> How can I implement such a get_paste() function?
> I need a non-blocking getkey() function.
> It must work on Windows and Linux.

Non-blocking I/O from the commandline is OS specific. There are 
different solutions, and it's usually hacky (stty on Linux, Console API 
on Windows)

Why do you not use a proper GUI toolkit to do this? It is 
straight-forward to accept keystrokes, copy/paste and drag'n'drop with 
most toolkits. Especially if you target Windows users, I think they 
would be more than happy to get a GUI app then to open a terminal window 
and paste something there. The standard terminal on Windows is very 
ugly, can't resize the width, and pasting works only if you right-click 
-> paste.

	Christian


From tjreedy at udel.edu  Wed Nov 18 04:47:56 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 18 Nov 2015 04:47:56 -0500
Subject: Writing SOME class methods in C
In-Reply-To: <slrnn4obfa.db7.dh@dotcom.mfs32>
References: <slrnn4obfa.db7.dh@dotcom.mfs32>
Message-ID: <n2hhgc$o3p$1@ger.gmane.org>

On 11/18/2015 2:50 AM, Daniel Haude wrote:
> Hello,
>
> I'm trying to implement some (but not all) methods of a Python class in C.
> What I've found on the Net is:
>   - how to implement entire modules in C so that I can import that module and
>     use the C functions (successfully done it, too).
>   - how to implement entire classes in C
>
> But I can't find any examples of modules which consist of a mixture of C and
> Python,

There at least to be such in the stdlib.  The .py module defined 
*everything* and then ended with

try:
     from _module import *
except ImportError:
     pass

to replace whatever top-level objects were also written in C.  The 
try-except part is optional but let the module run when _module was not 
present.  I believe the string module was once like this.

> nor modules that define classes of which some members are
> implemented in C, others in Python.

I would try putting the C part in separate base or mix-in class, 
imported before the class statement.  To make the C part optional:

class mixin: ...

try:
     from _module import mixin
except ImportError
     pass

class myclass(mixin): ...

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Wed Nov 18 05:02:13 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 18 Nov 2015 05:02:13 -0500
Subject: Is there any reason to introduce this intermediate variable (sz)?
In-Reply-To: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
References: <bad9ac66-38aa-4445-a486-6df0e9c7752c@googlegroups.com>
Message-ID: <n2hib5$61t$1@ger.gmane.org>

On 11/17/2015 3:51 PM, fl wrote:

> n_iter = 50
> sz = (n_iter,) # size of array
> x = -0.37727
> z = np.random.normal(x,0.1,size=sz)
>
> Q = 1e-5 # process variance
>
> # allocate space for arrays
> xhat=np.zeros(sz)
> P=np.zeros(sz)
>
>
> I learn Python now and the above code seems from an experienced author.
> The curious thing to me is the variable 'sz'.

'sz' is a name and in the program above, it is a constant tuple derived 
from constant int n_iter.  Since the tuple is used more than once, 
calculating it just once and naming it is a good idea.

 > I have check np.zeros(shape, ..)

Reading about the the signature of functions that you use or read about 
is a good idea and quite normal.

> shape : int or sequence of ints

> The introduced 'sz' is a tuple.

and tuples are sequences.

 > If n_iter function is similar to a constant in C,

n_iter is a named constant, not a function, as you note below.

 > I don't see the reason for 'sz'.

I gave a reason for it existig above, but I think you are asking about 
its use in the particular location.

> In fact, 'n_iter' is an int, which fits  the below
>
> np.zeros(shape)
>
> correctly.  Could you see something useful with variable 'sz'?

I would presume until I tried it that np.zeros(50) and np.zeros((50,)) 
are different (have a different shape).  If they are not, then the use 
of a singleton tuple is confusing, whether or not the tuple is given a name.

-- 
Terry Jan Reedy



From andrea.gavana at gmail.com  Wed Nov 18 05:31:34 2015
From: andrea.gavana at gmail.com (andrea.gavana at gmail.com)
Date: Wed, 18 Nov 2015 02:31:34 -0800 (PST)
Subject: cPickle.load vs. file.read+cPickle.loads on large binary files
In-Reply-To: <mailman.406.1447837229.16136.python-list@python.org>
References: <463ad93c-0186-4911-9cd1-92d97b9dc87b@googlegroups.com>
 <mailman.387.1447769670.16136.python-list@python.org>
 <54330891-6568-4469-93ae-7a7825961500@googlegroups.com>
 <mailman.392.1447773612.16136.python-list@python.org>
 <420ec4e9-6af6-49bd-a9f4-8b47ef1f136e@googlegroups.com>
 <n2fip9$ajg$1@ger.gmane.org>
 <mailman.406.1447837229.16136.python-list@python.org>
Message-ID: <f2a42caa-2cde-455b-83bb-3beef8e4c52f@googlegroups.com>

Hi,

On Wednesday, November 18, 2015 at 10:00:43 AM UTC+1, Nagy L?szl? Zsolt wrote:
> > Perhaps there is a size threshold? You could experiment with different block 
> > sizes in the following f.read() replacement:
> >
> > def read_chunked(f, size=2**20):
> >     read = functools.partial(f.read, size)
> >     return "".join(iter(read, ""))
> >
> Under win32 platform, my experience is that the fastest way to read
> binary file from disk is the mmap module. You should try that too.

Thank you for your suggestion. I have tried that now, and with my naive approach I have done this:

    start = time.time()
    fid = open(filename, 'r+b')
    strs = mmap.mmap(fid.fileno(), 0, access=mmap.ACCESS_READ)[:]
    end = time.time()
    print 'mmap.read time:', end-start

And it takes about 2.7 seconds. Not a bad improvement :-) . Unfortunately, when the file is on a network drive, all the other approaches ran at around 25-30 seconds loading time, while the mmap one clocks at 110 seconds :-(

Andrea.




From framstag at rus.uni-stuttgart.de  Wed Nov 18 05:39:52 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 10:39:52 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me>
Message-ID: <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>

Christian Gollwitzer <auriocus at gmx.de> wrote:

> > How can I implement such a get_paste() function?
> > I need a non-blocking getkey() function.
> > It must work on Windows and Linux.
> 
> Non-blocking I/O from the commandline is OS specific. There are 
> different solutions, and it's usually hacky (stty on Linux, Console API 
> on Windows)

A "if windows (...) else linux (...)" solution is ok, I have such
distinction already at several places in my code.

Do you have example code for non-blocking I/O?


> Why do you not use a proper GUI toolkit to do this? 

it is too complicated to rewrite my application from CLI to GUI.
But... is there a windows program with which one can select files and the
result is written to STDOUT?
Then I could use pipe open in my Python program.


> The standard terminal on Windows is very ugly, can't resize the width,
> and pasting works only if you right-click -> paste.

You can also use drag&drop. This is ok for my users.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From tjreedy at udel.edu  Wed Nov 18 05:52:57 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 18 Nov 2015 05:52:57 -0500
Subject: Launcher, and ftype Python.File
In-Reply-To: <564C32F3.2070909@g.nevcal.com>
References: <564C32F3.2070909@g.nevcal.com>
Message-ID: <564C5889.5040903@udel.edu>

On 11/18/2015 3:12 AM, Glenn Linderman wrote:
> Setting up a new machine with Windows 10, I installed Python 3.5.0 and
> the Launcher. Invoking python files from batch files as
>
> foo.py -a -bunch -of -parameters
>
> Didn't seem to do _anything_ so I checked:
>
> d:\>assoc .py
> .py=Python.File
>
> d:\>ftype Python.File
> Python.File="C:\Windows\py.exe" "%L" %*

Verified on my Win 10

> I'm surprised by the "%L" where usually programs have "%1". Is this a
> new Windows feature I don't know about yet, or is it a bug in the
> installer for the Launcher?

It puzzles me tool. However, it works.

> ftype /?  does not enlighten me that there is a new %L feature available.

I accidentally entered just 'ftype' and since WMP11 listings are at the 
end, noticed that they also use %L.  I also see that WMP11 listings are 
the only ones (other than Python.*) using %L.  Not even other MS 
listings, as for IE, do.

After entering 'ftype /?' as intended, I see that %0 and %1 are synonyms 
for the first word == the file being launched.  I also did not find 
mention of %L.  My guess is 'L' is a new term for 'Launched file'. 
Steve Dower, who wrote the 3.5 intaller, would know about it as a MS 
employer.

Steve, can you verify the above, and maybe tell whoever to update the 
ftype help?  Is there any difference (other than our puzzlement) between 
using %1 and %L?

> Turns out I had an empty file named foo.py and that is why it didn't do
> anything, but now I'm just really puzzled about what "%L" means...
> Google doesn't support searching for "%L" very well.


-- 
Terry Jan Reedy



From framstag at rus.uni-stuttgart.de  Wed Nov 18 06:01:59 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 11:01:59 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:

> it is too complicated to rewrite my application from CLI to GUI.
> But... is there a windows program with which one can select files and the
> result is written to STDOUT?

Found it:

	from Tkinter import Tk
	from tkFileDialog import askopenfilename

	Tk().withdraw()
	file = askopenfilename()


Hey, easy! :-)

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From auriocus at gmx.de  Wed Nov 18 06:17:07 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 18 Nov 2015 12:17:07 +0100
Subject: non-blocking getkey?
In-Reply-To: <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2hmj7$fht$1@dont-email.me>

Am 18.11.15 um 12:01 schrieb Ulli Horlacher:
> Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
>
>> it is too complicated to rewrite my application from CLI to GUI.
>> But... is there a windows program with which one can select files and the
>> result is written to STDOUT?
>
> Found it:
>
> 	from Tkinter import Tk
> 	from tkFileDialog import askopenfilename
>
> 	Tk().withdraw()
> 	file = askopenfilename()
>
>
> Hey, easy! :-)
>

Welcome to GUI programming ;) Do you still have other data to input? 
There are nice tutorials at http://tkdocs.com and for simple input like 
a single number or a line of text, there is a module simpledialog

	Christian


From steve at pearwood.info  Wed Nov 18 06:37:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 18 Nov 2015 22:37:20 +1100
Subject: Which type should be used when testing static structure
 appartenance
References: <mailman.388.1447770859.16136.python-list@python.org>
Message-ID: <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Wed, 18 Nov 2015 01:27 am, Nicolas ?vrard wrote:

> Hello,
> 
> I saw the following retweet by Raymond Hettinger in this morning:
> 
>     https://twitter.com/sanityinc/status/666485814214287360
> 
>     Programming tip: many of those arrays and hashes in your code
>     should actually be sets. Match data structures to data
>     constraints!

This is why I hold Twitter in contempt. What Raymond says could be a good
tip, or a load of old hogwash, and there is no way of knowing because you
can't explain much in 130 characters. If it were a blog post, he could
explain what he means. But its a tweet, so he can't.

Of course you should match the data structure to your data constraints, but
what does that mean in practice? *Which* arrays and hashes should be sets?
How do you know which should be changed to sets?


> I saw just in time because in a review I wrote something like this:
> 
>     if operator not in ('where', 'not where')
> 
> and my colleague proposed that I should use a list instead of a tuple.
> But reading the mentioned tweet I tend to think that a set would be a
> better choice.

Exactly. Raymond's tweet only serves to muddy the water and add more
confusion. Before, you thought you knew the right answer: use a tuple.
Then, your colleague proposed a list, adding some uncertainty and
confusion: which is better, a list or a tuple? And now Raymond's tweet has
*increased* the uncertainty: should you use a set?


> What are your opinion on this issue (I realize it's not something of
> the utmost importance but rather a "philosophical" question).

I would say that there is no doubt that in Python 2, using a tuple is far
and away the best solution for the situation you show above.


There are three factors to weigh up: 

(1) how easy is it to create the data structure?

(2) how much space does the data structure use?

(3) how fast is searching the data structure?


How easy is it to create the data structure? In Python 2, lists and tuples
are effectively just as easy to type, but sets not so much:

('where', 'not where')
['where', 'not where']
set(['where', 'not where'])


Not only are sets longer to type, but they are created at runtime. Compare
the byte-code compiled for each expression:


py> from dis import dis
py> a = compile("('where', 'not where')", "", "single")
py> b = compile("['where', 'not where']", "", "single")
py> c = compile("set(['where', 'not where'])", "", "single")
py> dis(a)
  1           0 LOAD_CONST               3 (('where', 'not where'))
              3 PRINT_EXPR
              4 LOAD_CONST               2 (None)
              7 RETURN_VALUE
py> dis(b)
  1           0 LOAD_CONST               0 ('where')
              3 LOAD_CONST               1 ('not where')
              6 BUILD_LIST               2
              9 PRINT_EXPR
             10 LOAD_CONST               2 (None)
             13 RETURN_VALUE
py> dis(c)
  1           0 LOAD_NAME                0 (set)
              3 LOAD_CONST               0 ('where')
              6 LOAD_CONST               1 ('not where')
              9 BUILD_LIST               2
             12 CALL_FUNCTION            1
             15 PRINT_EXPR
             16 LOAD_CONST               2 (None)
             19 RETURN_VALUE


Python can optimise the creation of the tuple to compile-time, but it has to
create the list at run time. It also creates the set at run time, but it
also needs to do a name lookup. All this takes time.

How much space does each data structure take? Again, a tuple easily wins
over the others:


py> import sys
py> sys.getsizeof(('where', 'not where'))
32
py> sys.getsizeof(['where', 'not where'])
40
py> sys.getsizeof(set(['where', 'not where']))
112

The tuple is smaller than the list, and MUCH smaller than the set. (The
exact sizes you see will depend on the precise version and platform you are
using, but I am confident that the tuple will win.)


Last but not least, which is fastest? For that, we can use the timeit
module, running it as a script from the shell:


[steve at ando ~]$ python -m timeit -s "x = 'not where'" "x in ('where', 'not
where')"
10000000 loops, best of 3: 0.122 usec per loop
[steve at ando ~]$ python -m timeit -s "x = 'not where'" "x in ['where', 'not
where']"
10000000 loops, best of 3: 0.119 usec per loop
[steve at ando ~]$ python -m timeit -s "x = 'not where'" "x in
set(['where', 'not where'])"
1000000 loops, best of 3: 0.728 usec per loop


The difference between 0.122 microseconds and 0.119 microseconds is too
close to call. We can say that the tuple and the list are equally fast, and
the set much, much slower.

But... we can speed the set up, by only creating it once:

[steve at ando ~]$ python -m timeit -s "x = 'not where'" -s "S =
set(['where', 'not where'])" "x in S"
10000000 loops, best of 3: 0.101 usec per loop

That's better! But only *marginally* faster than the tuple, and to get the
speed increase you have to factor out the set into a constant.

So for Python 2, I would say that tuples are the clean winner, at least for
the case where you only have two items to check. If you have more than two,
sets start becoming more attractive.


How about Python 3? Python 3 has the advantage of using set literals. Let's
test the speed:

[steve at ando ~]$ python3.3 -m timeit -s "x = 'not where'" "x in
('where', 'not where')"
10000000 loops, best of 3: 0.11 usec per loop
[steve at ando ~]$ python3.3 -m timeit -s "x = 'not where'" "x in
['where', 'not where']"
10000000 loops, best of 3: 0.113 usec per loop
[steve at ando ~]$ python3.3 -m timeit -s "x = 'not where'" "x in
{'where', 'not where'}"
10000000 loops, best of 3: 0.0907 usec per loop

This makes sets much more attractive in Python 3.


-- 
Steven



From tjreedy at udel.edu  Wed Nov 18 07:26:12 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 18 Nov 2015 07:26:12 -0500
Subject: non-blocking getkey?
In-Reply-To: <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2hqp5$fp5$1@ger.gmane.org>

On 11/18/2015 6:01 AM, Ulli Horlacher wrote:
> Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
>
>> it is too complicated to rewrite my application from CLI to GUI.
>> But... is there a windows program with which one can select files and the
>> result is written to STDOUT?
>
> Found it:
>
> 	from Tkinter import Tk
> 	from tkFileDialog import askopenfilename
>
> 	Tk().withdraw()
> 	file = askopenfilename()

To get multiple names, add 's'.  On Windows, one uses control-leftclick 
to get multiple names.  Don't know about other systems.

 >>> fd.askopenfilenames()  # ^click 4 names
('F:/Python/dev/27/Lib/idlelib/aboutDialog.py', 
'F:/Python/dev/27/Lib/idlelib/AutoComplete.py', 
'F:/Python/dev/27/Lib/idlelib/AutoCompleteWindow.pyc', 
'F:/Python/dev/27/Lib/idlelib/Bindings.py')

The limitation is that this will not work if any of the file names 
contain astral (non-BMP) chars because tk cannot handle such characters.

-- 
Terry Jan Reedy



From rosuav at gmail.com  Wed Nov 18 07:40:09 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 18 Nov 2015 23:40:09 +1100
Subject: Which type should be used when testing static structure
 appartenance
In-Reply-To: <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.388.1447770859.16136.python-list@python.org>
 <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmogJNzqMs4HOk0i9PqD0WDt+_Jz_NokQa6=CqepyQ4xdg@mail.gmail.com>

On Wed, Nov 18, 2015 at 10:37 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> How about Python 3? Python 3 has the advantage of using set literals.

2.7 has set literals too. All the questions of performance should be
secondary to code clarity, though; so I would say the choices are: Set
literal if available, else tuple. Forget the performance.

ChrisA


From oscar.j.benjamin at gmail.com  Wed Nov 18 07:52:26 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Wed, 18 Nov 2015 12:52:26 +0000
Subject: Writing SOME class methods in C
In-Reply-To: <slrnn4obfa.db7.dh@dotcom.mfs32>
References: <slrnn4obfa.db7.dh@dotcom.mfs32>
Message-ID: <CAHVvXxSEN5PYeJ==u=fWKxAkmsZXU8FhsFOFDQd_05T8M5OgBw@mail.gmail.com>

On 18 November 2015 at 07:50, Daniel Haude <dh at dotcom.mfs32> wrote:
>
> I'm trying to implement some (but not all) methods of a Python class in C.
> What I've found on the Net is:
>  - how to implement entire modules in C so that I can import that module and
>    use the C functions (successfully done it, too).
>  - how to implement entire classes in C

I would suggest to use Cython here. You can write your class in Python
(that will be compiled to C) and then call out to any C code from any
of its methods.

Alternatively Terry's suggestion to implement a class in C and then
subclass it in Python to add the remaining methods is a good one. But
then I would write the C class using Cython so I may as well do the
whole thing in Cython.

--
Oscar


From mal at europython.eu  Wed Nov 18 08:05:53 2015
From: mal at europython.eu (M.-A. Lemburg)
Date: Wed, 18 Nov 2015 14:05:53 +0100
Subject: EuroPython 2016: Dates and URL available
Message-ID: <564C77B1.2060201@europython.eu>

The EuroPython 2016 Team is pleased to account the dates for
EuroPython 2016 in Bilbao, Basque Country, Spain:

                  Sunday, July 17 - Sunday, July 24 2016

Pre-launch Website
------------------

To keep you updated, we have put together a pre-launch website for the
conference:

                   *** http://ep2016.europython.eu/ ***

Beginners? Day
--------------

You may wonder why we?re having an extra day for the
conference. Here?s the plan:

In 2015, we introduced Beginners? Day as a new format to EuroPython
providing special introductions and tutorials for Python
beginners. The project was a great success.

For the 2016 edition, we are planning to dedicate Sunday before the
main conference as Beginner?s Day, so we?ll have the following
conference layout:

 * Sunday, July 17: Beginners? day & registration
 * Monday, July 18 - Friday, July 22: Main conference & trainings
 * Saturday, July 23 - Sunday, July 24: Sprints

Looking for Launch Sponsors
---------------------------

We will launch the conference website in December. If your company
would like to sponsor EuroPython 2016 and get extra attention by being
one of our launch sponsors, please check our sponsor page for details.


Enjoy,
--
EuroPython 2016 Team
http://ep2016.europython.eu/
http://www.europython-society.org/


From framstag at rus.uni-stuttgart.de  Wed Nov 18 08:06:31 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 13:06:31 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
Message-ID: <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>

Terry Reedy <tjreedy at udel.edu> wrote:

> >       from Tkinter import Tk
> >       from tkFileDialog import askopenfilename
> >
> >       Tk().withdraw()
> >       file = askopenfilename()
> 
> To get multiple names, add 's'. 

I have found it already, thanks.


> The limitation is that this will not work if any of the file names 
> contain astral (non-BMP) chars because tk cannot handle such characters.

What are "astral chars"?

But anyway, askopenfilename() is a dead end for me: one cannot select
directories with it, just plain files.
In my application the user MUST select files and directories (in one go).


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rosuav at gmail.com  Wed Nov 18 08:24:11 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 00:24:11 +1100
Subject: non-blocking getkey?
In-Reply-To: <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me>
 <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
Message-ID: <CAPTjJmqkN8dLzqE5Fmt7HN0A_SbaHUoZ_wM7v1PctoFoK=3Uow@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:06 AM, Ulli Horlacher
<framstag at rus.uni-stuttgart.de> wrote:
>> The limitation is that this will not work if any of the file names
>> contain astral (non-BMP) chars because tk cannot handle such characters.
>
> What are "astral chars"?

Characters not on the Basic Multilingual Plane (BMP). The Unicode
character set is divided into a number of planes of 65,536 codepoints
each, with the most commonly used ones on the first plane, the BMP. A
lot of programs either cannot use non-BMP characters or have problems
with them; for instance, anything that uses UTF-16 as its internal
representation (ECMAScript, notably; also Python 2 on Windows) sees
astral characters as pairs of code points.

> In my application the user MUST select files and directories (in one go).

It's extremely uncommon to be able to select a combination of files
and directories. The UI for this would be quite annoying, I think. You
may find it easier to have your own wrapper; for example, have a list
of selected files/directories, with buttons "Add File" and "Add
Directory" underneath. The former would use askopenfilenames (despite
the singular in the button name), and the latter would use
askdirectory. Trying to do both at once would be hard.

ChrisA


From steve at pearwood.info  Wed Nov 18 08:30:36 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 19 Nov 2015 00:30:36 +1100
Subject: Which type should be used when testing static structure
 appartenance
References: <mailman.388.1447770859.16136.python-list@python.org>
 <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>
 <mailman.411.1447850412.16136.python-list@python.org>
Message-ID: <564c7d80$0$1606$c3e8da3$5496439d@news.astraweb.com>

On Wed, 18 Nov 2015 11:40 pm, Chris Angelico wrote:

> On Wed, Nov 18, 2015 at 10:37 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> How about Python 3? Python 3 has the advantage of using set literals.
> 
> 2.7 has set literals too. 

Ah, so it does. I forgot about that. Most of my code has to run on multiple
versions (back to 2.4) and I remembered that set literals don't work:

[steve at ando ~]$ python2.6 -c "{1, 2, 3}"
  File "<string>", line 1
    {1, 2, 3}
      ^
SyntaxError: invalid syntax


> All the questions of performance should be 
> secondary to code clarity, though; 

"All"? Surely not.


> so I would say the choices are: Set 
> literal if available, else tuple. Forget the performance.

It seems rather strange to argue that we should ignore performance when the
whole reason for using sets in the first place is for performance.


-- 
Steven



From jon+usenet at unequivocal.co.uk  Wed Nov 18 08:32:29 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Wed, 18 Nov 2015 13:32:29 -0000 (UTC)
Subject: Which type should be used when testing static structure
 appartenance
References: <mailman.388.1447770859.16136.python-list@python.org>
 <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>
 <mailman.411.1447850412.16136.python-list@python.org>
 <564c7d80$0$1606$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <slrnn4ovjp.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-18, Steven D'Aprano <steve at pearwood.info> wrote:
> On Wed, 18 Nov 2015 11:40 pm, Chris Angelico wrote:
>> so I would say the choices are: Set 
>> literal if available, else tuple. Forget the performance.
>
> It seems rather strange to argue that we should ignore performance when the
> whole reason for using sets in the first place is for performance.

Who says the whole reason for using sets is performance? Sets behave
differently to tuples or lists - the members are guaranteed to be
unique.


From steve at pearwood.info  Wed Nov 18 08:38:25 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 19 Nov 2015 00:38:25 +1100
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
Message-ID: <564c7f54$0$1597$c3e8da3$5496439d@news.astraweb.com>

On Thu, 19 Nov 2015 12:06 am, Ulli Horlacher wrote:

> Terry Reedy <tjreedy at udel.edu> wrote:
> 
>> >       from Tkinter import Tk
>> >       from tkFileDialog import askopenfilename
>> >
>> >       Tk().withdraw()
>> >       file = askopenfilename()
>> 
>> To get multiple names, add 's'.
> 
> I have found it already, thanks.
> 
> 
>> The limitation is that this will not work if any of the file names
>> contain astral (non-BMP) chars because tk cannot handle such characters.
> 
> What are "astral chars"?

Unicode characters beyond U+FFFF.

Unicode covers the entire range of code points (informally characters, don't
worry about the technical difference) from U+0000 to U+10FFFF. The part
following the "U+" is the numeric ordinal value, written in hexadecimal.

Some older versions of Unicode only included 2**16 == 65536 distinct
characters, but many years ago Unicode was extended far beyond that number.
But the first 65536 characters are called the "Basic Multilingual Plane".
All the rest are in the "Supplementary Multilingual Planes", which being a
mouthful to say and write, often gets abbreviated as "astral planes". Hence
the characters themselves are called "astral characters".

Even today, some programming languages and systems have difficulty dealing
with characters that require more than two bytes.

-- 
Steven



From rosuav at gmail.com  Wed Nov 18 08:42:32 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 00:42:32 +1100
Subject: Which type should be used when testing static structure
 appartenance
In-Reply-To: <564c7d80$0$1606$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.388.1447770859.16136.python-list@python.org>
 <564c62f3$0$1593$c3e8da3$5496439d@news.astraweb.com>
 <mailman.411.1447850412.16136.python-list@python.org>
 <564c7d80$0$1606$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrf8UUOBR6UG1UUJuhA0_UyBUOk+haPYJv-KYmdZumX9A@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:30 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Wed, 18 Nov 2015 11:40 pm, Chris Angelico wrote:
>> All the questions of performance should be
>> secondary to code clarity, though;
>
> "All"? Surely not.

The OP's example was checking if a string was equal to either of two
strings. Even if that's in a tight loop, the performance difference
between the various options is negligible.

The "all" is a little misleading (of course there are times when you
warp your code for the sake of performance), but I was talking about
this example, where it's basically coming down to microbenchmarks.

>> so I would say the choices are: Set
>> literal if available, else tuple. Forget the performance.
>
> It seems rather strange to argue that we should ignore performance when the
> whole reason for using sets in the first place is for performance.

They do perform well, but that's not the main point - not when you're
working with just two strings. Of course, when you can get performance
AND readability, it's perfect. That doesn't happen with Py2 sets, but
it does with Python 3:

rosuav at sikorsky:~$ python -m timeit -s "x='asdf'" "x in {'asdf','qwer'}"
10000000 loops, best of 3: 0.12 usec per loop
rosuav at sikorsky:~$ python -m timeit -s "x='asdf'" "x in ('asdf','qwer')"
10000000 loops, best of 3: 0.0344 usec per loop
rosuav at sikorsky:~$ python -m timeit -s "x='asdf'" "x=='asdf' or x=='qwer'"
10000000 loops, best of 3: 0.0392 usec per loop
rosuav at sikorsky:~$ python3 -m timeit -s "x='asdf'" "x in {'asdf','qwer'}"
10000000 loops, best of 3: 0.0356 usec per loop
rosuav at sikorsky:~$ python3 -m timeit -s "x='asdf'" "x in ('asdf','qwer')"
10000000 loops, best of 3: 0.0342 usec per loop
rosuav at sikorsky:~$ python3 -m timeit -s "x='asdf'" "x=='asdf' or x=='qwer'"
10000000 loops, best of 3: 0.0418 usec per loop

No set construction in Py3 - the optimizer figures out that you don't
need mutability, and uses a constant frozenset. (Both versions do this
with list->tuple.) Despite the performance hit from using a set in
Py2, though, I would still advocate its use (assuming you don't need
to support 2.6 or older), because it accurately represents the
*concept* of "is this any one of these".

ChrisA


From framstag at rus.uni-stuttgart.de  Wed Nov 18 08:51:33 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 13:51:33 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
 <564c7f54$0$1597$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2hvp5$fun$1@news2.informatik.uni-stuttgart.de>

Steven D'Aprano <steve at pearwood.info> wrote:

> >> The limitation is that this will not work if any of the file names
> >> contain astral (non-BMP) chars because tk cannot handle such characters.
> > 
> > What are "astral chars"?
> 
> Unicode characters beyond U+FFFF.

I see, for very exotic character sets, like Klingon, etc :-)
In my case, I can simple ignore them.


> Unicode covers the entire range of code points (informally characters, don't
> worry about the technical difference) from U+0000 to U+10FFFF. The part
> following the "U+" is the numeric ordinal value, written in hexadecimal.

That was my knowledge so far.


> Some older versions of Unicode only included 2**16 == 65536 distinct
> characters, but many years ago Unicode was extended far beyond that number.
> But the first 65536 characters are called the "Basic Multilingual Plane".
> All the rest are in the "Supplementary Multilingual Planes", which being a
> mouthful to say and write, often gets abbreviated as "astral planes". Hence
> the characters themselves are called "astral characters".

And this was new to me. Learned :-)

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From framstag at rus.uni-stuttgart.de  Wed Nov 18 08:57:53 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 13:57:53 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
 <mailman.414.1447853060.16136.python-list@python.org>
Message-ID: <n2i051$fun$2@news2.informatik.uni-stuttgart.de>

Chris Angelico <rosuav at gmail.com> wrote:

> > In my application the user MUST select files and directories (in one go).
> 
> It's extremely uncommon to be able to select a combination of files
> and directories. 

I have an uncommon application :-)
Filetransfer of ANY size: http://fex.rus.uni-stuttgart.de:8080/


> The UI for this would be quite annoying, I think. You may find it easier
> to have your own wrapper; for example, have a list of selected
> files/directories, with buttons "Add File" and "Add Directory"
> underneath.

I came (independantly) to the same solution!
So it must be a good idea :-)

http://fex.rus.uni-stuttgart.de:8080/fop/3yxsCacS/X-20151118145221.png


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rosuav at gmail.com  Wed Nov 18 09:01:32 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 01:01:32 +1100
Subject: non-blocking getkey?
In-Reply-To: <n2hvp5$fun$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me>
 <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
 <564c7f54$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <n2hvp5$fun$1@news2.informatik.uni-stuttgart.de>
Message-ID: <CAPTjJmoq--juiGuQHqCWGfn_V+m--6_-_yzC9wMX_e-e=teoOA@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:51 AM, Ulli Horlacher
<framstag at rus.uni-stuttgart.de> wrote:
> Steven D'Aprano <steve at pearwood.info> wrote:
>
>> >> The limitation is that this will not work if any of the file names
>> >> contain astral (non-BMP) chars because tk cannot handle such characters.
>> >
>> > What are "astral chars"?
>>
>> Unicode characters beyond U+FFFF.
>
> I see, for very exotic character sets, like Klingon, etc :-)
> In my case, I can simple ignore them.

And other exotic character sets, like Chinese.

https://en.wikipedia.org/wiki/CJK_Unified_Ideographs#CJK_Unified_Ideographs_Extension_B

But I'm sure you can ignore them, too. Hardly anyone on this planet
speaks Chinese.

ChrisA


From harvesting at makes.invalid  Wed Nov 18 09:13:56 2015
From: harvesting at makes.invalid (Jussi Piitulainen)
Date: Wed, 18 Nov 2015 16:13:56 +0200
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me>
 <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <mailman.410.1447849595.16136.python-list@python.org>
 <n2ht4n$fas$1@news2.informatik.uni-stuttgart.de>
 <564c7f54$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <n2hvp5$fun$1@news2.informatik.uni-stuttgart.de>
Message-ID: <lf5k2pfz97f.fsf@ling.helsinki.fi>

Ulli Horlacher writes:
> Steven D'Aprano wrote:
>
>> >> The limitation is that this will not work if any of the file names
>> >> contain astral (non-BMP) chars because tk cannot handle such
>> >> characters.
>> > 
>> > What are "astral chars"?
>> 
>> Unicode characters beyond U+FFFF.
>
> I see, for very exotic character sets, like Klingon, etc :-)
> In my case, I can simple ignore them.

Better test how your user interface behaves when a user copy-pastes one
of those characters into it. If it merely garbles the character somehow,
you may be able to ignore the problem, but if it promptly shuts down
your whole application and loses some unfinished work, the user may not
be happy.

Klingon may not be that widely spoken, but all manner of little picture
characters seem popular. Wasn't one just chosen to be the Word Of The
Year? And when it's the underlying GUI library that crashes, it's too
late for your program to sanitize the input.


From chris at chrullrich.net  Wed Nov 18 09:45:54 2015
From: chris at chrullrich.net (Christian Ullrich)
Date: Wed, 18 Nov 2015 15:45:54 +0100
Subject: Launcher, and ftype Python.File
In-Reply-To: <mailman.409.1447844007.16136.python-list@python.org>
References: <564C32F3.2070909@g.nevcal.com>
 <mailman.409.1447844007.16136.python-list@python.org>
Message-ID: <db3h92Fpu11U1@mid.individual.net>

* Terry Reedy wrote:

> On 11/18/2015 3:12 AM, Glenn Linderman wrote:

>> d:\>ftype Python.File
>> Python.File="C:\Windows\py.exe" "%L" %*
>
> Verified on my Win 10
>
>> I'm surprised by the "%L" where usually programs have "%1". Is this a
>> new Windows feature I don't know about yet, or is it a bug in the
>> installer for the Launcher?
>
> It puzzles me tool. However, it works.

Apparently %L is always the long file name, and %1 is the short name 
unless the shell can prove that the executable can handle long names.

>> Google doesn't support searching for "%L" very well.

https://www.google.com/search?q=ftype+%22%25L%22#q=ftype+%22%25L%22+-mks

-- 
Christian




From durozoyp at gmail.com  Wed Nov 18 11:34:43 2015
From: durozoyp at gmail.com (durozoyp at gmail.com)
Date: Wed, 18 Nov 2015 08:34:43 -0800 (PST)
Subject: link a treeview to a list
Message-ID: <650de6af-2ae1-4218-8d14-d06c84fc5cc9@googlegroups.com>

So I am currently making a little program that generates a list of characters with different stats. Now I would like to display those characters in a list and when the user clicks on one of them display all the stats for that character.

Here is my code for my GUI so far:

class CTABLE:
    def __init__(self, master):

        self.charactersTable = ttk.Treeview(master, selectmode="browse")
        self.charactersTable["show"] = "headings"
        self.charactersTable["columns"]=("Name", "Surname", "Hunger",
            "Fear", "Comfort", "Hapiness")
        self.charactersTable.column("Name", width=100, anchor=E)
        self.charactersTable.heading("Name", text="Name")
        self.charactersTable.column("Surname", width=100, anchor=E)
        self.charactersTable.heading("Surname", text="Surname")
        self.charactersTable.column("Hunger", width=100, anchor=E)
        self.charactersTable.heading("Hunger", text="Hunger")
        self.charactersTable.column("Fear", width=100, anchor=E)
        self.charactersTable.heading("Fear", text="Fear")
        self.charactersTable.column("Comfort", width=100, anchor=E)
        self.charactersTable.heading("Comfort", text="Comfort")
        self.charactersTable.column("Hapiness", width=100, anchor=E)
        self.charactersTable.heading("Hapiness", text="Hapiness")

        for character in characters:
            self.charactersTable.insert("", "end", values=(character.surname, character.name, 
            character.hunger, character.fear, character.comfort,
            character.happiness))
        self.charactersTable.bind("<Double-1>", self.CTClick)
        self.charactersTable.grid(row=1, rowspan=3, column=1)

    def CTClick(self, event):

        item = self.charactersTable.selection()[0]
        print (self.charactersTable.item(item))


My problem is that my CTClick event refers to the line in the treeview object and not the character object itself and I don't know how to fix that


From ryanshuell at gmail.com  Wed Nov 18 11:37:47 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 18 Nov 2015 08:37:47 -0800 (PST)
Subject: How can I export data from a website and write the contents to a text
 file?
Message-ID: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>

I'm trying the script below, and it simple writes the last line to a text file.  I want to add a '\n' after each line is written, so I don't overwrite all the lines.


from bs4 import BeautifulSoup
import urllib2

var_file = urllib2.urlopen("http://www.imdb.com/chart/top")

var_html  = var_file.read()

var_file.close()
soup = BeautifulSoup(var_html)
for item in soup.find_all(class_='lister-list'):
    for link in item.find_all('a'):
        print(link)
        text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
        z = str(link)
        text_file.write(z + "\n")
        text_file.write("\n")
        text_file.close()


Can someone please help me get this working?
Thanks!!


From framstag at rus.uni-stuttgart.de  Wed Nov 18 11:45:49 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 16:45:49 +0000 (UTC)
Subject: handling of non-ASCII filenames?
Message-ID: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>

I have written a program (Python 2.7) which reads a filename via
tkFileDialog.askopenfilename() (was a good hint here, other thread).

This filename may contain non-ASCII characters (German Umlauts).

In this case my program crashes with:

  File "S:\python\fexit.py", line 1177, in url_encode
      u += '%' + c.encode("hex").upper()
  File "C:\Python27\lib\encodings\hex_codec.py", line 24, in hex_encode
    output = binascii.b2a_hex(input)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xf6' in position 0: ordinal not in range(128)


This is my encoding function:

def url_encode(s):
  u = ''
  for c in list(s):
    if match(r'[_=:,;<>()+.\w\-]',c): 
      u += c
    else:
      u += '%' + c.encode("hex").upper()
  return u



As I am Python newbie I have not quite understood the Python character
encoding scheme :-}

Where can I find a good introduction of this topic?

I would also appreciate a concrete solution for my problem :-)

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From framstag at rus.uni-stuttgart.de  Wed Nov 18 11:50:11 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 16:50:11 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:

>         from Tkinter import Tk
>         from tkFileDialog import askopenfilename
> 
>         Tk().withdraw()
>         file = askopenfilename()

I found another glitch:

After termination of askopenfilename() the window focus is not returned to
the calling window (xterm on Linux, cmd on Windows). I have to click it
again, to regain the focus and continue typing. Is there a workaround?



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rosuav at gmail.com  Wed Nov 18 11:54:58 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 03:54:58 +1100
Subject: handling of non-ASCII filenames?
In-Reply-To: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
Message-ID: <CAPTjJmpSdJaUSxA6770M59tCSQPJ+-zZ2mZF2q8BiqT9y9HS=g@mail.gmail.com>

On Thu, Nov 19, 2015 at 3:45 AM, Ulli Horlacher
<framstag at rus.uni-stuttgart.de> wrote:
> As I am Python newbie I have not quite understood the Python character
> encoding scheme :-}
>
> Where can I find a good introduction of this topic?

Here are a couple of articles on the basics of Unicode:

http://www.joelonsoftware.com/articles/Unicode.html

http://nedbatchelder.com/text/unipain.html

If you can use Python 3, your life will be easier. Otherwise, you'll
need to work some of this stuff out manually.

ChrisA


From rosuav at gmail.com  Wed Nov 18 11:57:58 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 03:57:58 +1100
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
Message-ID: <CAPTjJmpEAkaN9SLXC7OAspfXVmspmx4EWfVDMk+3adHMBjh=LA@mail.gmail.com>

On Thu, Nov 19, 2015 at 3:37 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
>       text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
>         z = str(link)
>         text_file.write(z + "\n")
>         text_file.write("\n")
>         text_file.close()

You're opening the file every time you go through the loop,
overwriting each time. Instead, open the file once, then start the
loop, and then close it at the end. You can use a 'with' statement to
do the closing for you, or you can do it the way you are here.

ChrisA


From ryanshuell at gmail.com  Wed Nov 18 12:03:58 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 18 Nov 2015 09:03:58 -0800 (PST)
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <mailman.418.1447865881.16136.python-list@python.org>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <mailman.418.1447865881.16136.python-list@python.org>
Message-ID: <099133ed-c6df-4f5c-b47b-f1cf464511f6@googlegroups.com>

On Wednesday, November 18, 2015 at 11:58:17 AM UTC-5, Chris Angelico wrote:
> On Thu, Nov 19, 2015 at 3:37 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
> >       text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
> >         z = str(link)
> >         text_file.write(z + "\n")
> >         text_file.write("\n")
> >         text_file.close()
> 
> You're opening the file every time you go through the loop,
> overwriting each time. Instead, open the file once, then start the
> loop, and then close it at the end. You can use a 'with' statement to
> do the closing for you, or you can do it the way you are here.
> 
> ChrisA



Thanks.  What would the code look like?  I tried the code below, and got the same results.


for item in soup.find_all(class_='lister-list'):
    for link in item.find_all('a'):
        #print(link)
        z = str(link)
        text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
        text_file.write(z + "\n")
        text_file.close()





From ryanshuell at gmail.com  Wed Nov 18 12:15:20 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 18 Nov 2015 09:15:20 -0800 (PST)
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <099133ed-c6df-4f5c-b47b-f1cf464511f6@googlegroups.com>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <mailman.418.1447865881.16136.python-list@python.org>
 <099133ed-c6df-4f5c-b47b-f1cf464511f6@googlegroups.com>
Message-ID: <9ddeb643-292f-4d5a-a891-83bee1d35c2f@googlegroups.com>

On Wednesday, November 18, 2015 at 12:04:16 PM UTC-5, ryguy7272 wrote:
> On Wednesday, November 18, 2015 at 11:58:17 AM UTC-5, Chris Angelico wrote:
> > On Thu, Nov 19, 2015 at 3:37 AM, ryguy7272 <> wrote:
> > >       text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
> > >         z = str(link)
> > >         text_file.write(z + "\n")
> > >         text_file.write("\n")
> > >         text_file.close()
> > 
> > You're opening the file every time you go through the loop,
> > overwriting each time. Instead, open the file once, then start the
> > loop, and then close it at the end. You can use a 'with' statement to
> > do the closing for you, or you can do it the way you are here.
> > 
> > ChrisA
> 
> 
> 
> Thanks.  What would the code look like?  I tried the code below, and got the same results.
> 
> 
> for item in soup.find_all(class_='lister-list'):
>     for link in item.find_all('a'):
>         #print(link)
>         z = str(link)
>         text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
>         text_file.write(z + "\n")
>         text_file.close()


Oh, I see, it's like this:

text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
var_file.close()
soup = BeautifulSoup(var_html)
for item in soup.find_all(class_='lister-list'):
    for link in item.find_all('a'):
        #print(link)
        z = str(link)
        text_file.write(z + "\n")
text_file.close()


However, it's not organized very well, and it's hard to read.  I thought the '\n' would create a new line after one line was written.  Now, it seems like everything is jumbled together.  Kind of weird.  Am I missing something?


From denismfmcmahon at gmail.com  Wed Nov 18 12:19:13 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Wed, 18 Nov 2015 17:19:13 -0000 (UTC)
Subject: How can I export data from a website and write the contents to a
 text file?
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
Message-ID: <n2ibuh$bm9$2@dont-email.me>

On Wed, 18 Nov 2015 08:37:47 -0800, ryguy7272 wrote:

> I'm trying the script below...

The problem isn't that you're over-writing the lines (although it may 
seem that way to you), the problem is that you're overwriting the whole 
file every time you write a link to it. This is because you open and 
close the file for every link you write, and you do so in file mode "wb" 
which restarts writing at the first byte of the file every time.

You only need to open and close the text file once, instead of for every 
link you output. Try moving the lines to open and close the file outside 
the outer for loop to change the loop from:

for item in soup.find_all(class_='lister-list'):
    for link in item.find_all('a'):
        # open file
        # write link to file
        # close file

to:

# open file
for item in soup.find_all(class_='lister-list'):
    for link in item.find_all('a'):
        # write link to file
# close file

Alternatively, use the with form:

with open("blah","wb") as text_file:
    for item in soup.find_all(class_='lister-list'):
        for link in item.find_all('a'):
            # write link to file

-- 
Denis McMahon, denismfmcmahon at gmail.com


From auriocus at gmx.de  Wed Nov 18 12:22:05 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Wed, 18 Nov 2015 18:22:05 +0100
Subject: handling of non-ASCII filenames?
In-Reply-To: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n2ibvh$5th$1@dont-email.me>

Am 18.11.15 um 17:45 schrieb Ulli Horlacher:
> This is my encoding function:
>
> def url_encode(s):
>    u = ''
>    for c in list(s):
>      if match(r'[_=:,;<>()+.\w\-]',c):
>        u += c
>      else:
>        u += '%' + c.encode("hex").upper()
>    return u
>
>

The quoting is applied to a UTF8 string. But I think you shouldn't do it 
yourself,  use a library function:

import urllib
urllib.quote(yourstring.encode('utf8'))

	Christian


From ryanshuell at gmail.com  Wed Nov 18 12:40:58 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 18 Nov 2015 09:40:58 -0800 (PST)
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <n2ibuh$bm9$2@dont-email.me>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <n2ibuh$bm9$2@dont-email.me>
Message-ID: <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>

On Wednesday, November 18, 2015 at 12:21:47 PM UTC-5, Denis McMahon wrote:
> On Wed, 18 Nov 2015 08:37:47 -0800, ryguy7272 wrote:
> 
> > I'm trying the script below...
> 
> The problem isn't that you're over-writing the lines (although it may 
> seem that way to you), the problem is that you're overwriting the whole 
> file every time you write a link to it. This is because you open and 
> close the file for every link you write, and you do so in file mode "wb" 
> which restarts writing at the first byte of the file every time.
> 
> You only need to open and close the text file once, instead of for every 
> link you output. Try moving the lines to open and close the file outside 
> the outer for loop to change the loop from:
> 
> for item in soup.find_all(class_='lister-list'):
>     for link in item.find_all('a'):
>         # open file
>         # write link to file
>         # close file
> 
> to:
> 
> # open file
> for item in soup.find_all(class_='lister-list'):
>     for link in item.find_all('a'):
>         # write link to file
> # close file
> 
> Alternatively, use the with form:
> 
> with open("blah","wb") as text_file:
>     for item in soup.find_all(class_='lister-list'):
>         for link in item.find_all('a'):
>             # write link to file
> 
> -- 
> Denis McMahon, 


Yes, I just figured it out.  Thanks.  

It doesn't seem like the '\n' is doing anything useful.  All the text is jumbled together.  When I open the file in Excel, or Notepad++, it is easy to read.  However, when I open it in as a regular text file, everything is jumbled together.  Is there an easy way to fix this?


From ryanshuell at gmail.com  Wed Nov 18 12:43:59 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 18 Nov 2015 09:43:59 -0800 (PST)
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <n2ibuh$bm9$2@dont-email.me>
 <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>
Message-ID: <e0edf996-9ce8-404e-b4e0-1e9a7b9af706@googlegroups.com>

On Wednesday, November 18, 2015 at 12:41:19 PM UTC-5, ryguy7272 wrote:
> On Wednesday, November 18, 2015 at 12:21:47 PM UTC-5, Denis McMahon wrote:
> > On Wed, 18 Nov 2015 08:37:47 -0800, ryguy7272 wrote:
> > 
> > > I'm trying the script below...
> > 
> > The problem isn't that you're over-writing the lines (although it may 
> > seem that way to you), the problem is that you're overwriting the whole 
> > file every time you write a link to it. This is because you open and 
> > close the file for every link you write, and you do so in file mode "wb" 
> > which restarts writing at the first byte of the file every time.
> > 
> > You only need to open and close the text file once, instead of for every 
> > link you output. Try moving the lines to open and close the file outside 
> > the outer for loop to change the loop from:
> > 
> > for item in soup.find_all(class_='lister-list'):
> >     for link in item.find_all('a'):
> >         # open file
> >         # write link to file
> >         # close file
> > 
> > to:
> > 
> > # open file
> > for item in soup.find_all(class_='lister-list'):
> >     for link in item.find_all('a'):
> >         # write link to file
> > # close file
> > 
> > Alternatively, use the with form:
> > 
> > with open("blah","wb") as text_file:
> >     for item in soup.find_all(class_='lister-list'):
> >         for link in item.find_all('a'):
> >             # write link to file
> > 
> > -- 
> > Denis McMahon, 
> 
> 
> Yes, I just figured it out.  Thanks.  
> 
> It doesn't seem like the '\n' is doing anything useful.  All the text is jumbled together.  When I open the file in Excel, or Notepad++, it is easy to read.  However, when I open it in as a regular text file, everything is jumbled together.  Is there an easy way to fix this?

I finally got it working.  It's like this:
"\r\n"

Thanks everyone!!


From tjreedy at udel.edu  Wed Nov 18 12:55:33 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Wed, 18 Nov 2015 12:55:33 -0500
Subject: non-blocking getkey?
In-Reply-To: <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2ie2l$346$1@ger.gmane.org>

On 11/18/2015 11:50 AM, Ulli Horlacher wrote:
> Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
>
>>          from Tkinter import Tk
>>          from tkFileDialog import askopenfilename
>>
>>          Tk().withdraw()
>>          file = askopenfilename()
>
> I found another glitch:
>
> After termination of askopenfilename() the window focus is not returned to
> the calling window (xterm on Linux, cmd on Windows). I have to click it
> again, to regain the focus and continue typing. Is there a workaround?

What happens with

root = Tk()
root.withdraw()
fiel = ...
root.destroy()

Focus cannot stay with destroyed window.

-- 
Terry Jan Reedy



From eryksun at gmail.com  Wed Nov 18 13:03:51 2015
From: eryksun at gmail.com (eryksun)
Date: Wed, 18 Nov 2015 12:03:51 -0600
Subject: Launcher, and ftype Python.File
In-Reply-To: <db3h92Fpu11U1@mid.individual.net>
References: <564C32F3.2070909@g.nevcal.com>
 <mailman.409.1447844007.16136.python-list@python.org>
 <db3h92Fpu11U1@mid.individual.net>
Message-ID: <CACL+1aujCJ+G1f+yXeFXjdyWF25L8Bgt3ahkUWYHQ8MGUebyGg@mail.gmail.com>

On Wed, Nov 18, 2015 at 8:45 AM, Christian Ullrich <chris at chrullrich.net> wrote:
> Apparently %L is always the long file name, and %1 is the short name unless
> the shell can prove that the executable can handle long names.

Specifically old Win16 programs (identified by the file header) aren't
aware of long filenames. In the case of these old programs, the shell
calls GetShortPathName when replacing %0 or %1, but not when replacing
%L.

For Win32 programs %0, %1, and %L are all the same:

    C:\Temp>ftype Python.File
    Python.File="C:\Windows\py.exe" "%0" "%1" "%L" %*

    C:\Temp>longfilename.py
    sys.argv:
    C:\Temp\longfilename.py
    C:\Temp\longfilename.py
    C:\Temp\longfilename.py

    Short Pathname:
    C:\Temp\LONGFI~1.PY


From rgaddi at technologyhighland.invalid  Wed Nov 18 13:05:33 2015
From: rgaddi at technologyhighland.invalid (Rob Gaddi)
Date: Wed, 18 Nov 2015 18:05:33 -0000 (UTC)
Subject: How can I export data from a website and write the contents to
 a text file?
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <n2ibuh$bm9$2@dont-email.me>
 <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>
Message-ID: <n2ield$bbq$2@dont-email.me>

On Wed, 18 Nov 2015 09:40:58 -0800, ryguy7272 wrote:
> 
> It doesn't seem like the '\n' is doing anything useful.  All the text is
> jumbled together.  When I open the file in Excel, or Notepad++, it is
> easy to read.  However, when I open it in as a regular text file,
> everything is jumbled together.  Is there an easy way to fix this?

You're suffering cause-effect inversion.  Windows default Notepad is a 
fundamentally crippled text editor that only knows how to handle Windows/
DOS style text files, where the line endings is '\n\r'.  Notepad++, along 
with many other excellent editors available for Windows, is smart enough 
to figure out from the file whether it's Windows style or UNIX style, 
where line endings are just a bare '\n'.

So the problem wasn't with what you were writing, it's with how you 
define "open it as a regular text file".  On my Windows machine I long 
ago switched the default editor to Notepad++ for everything and was far 
happier for it.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.


From framstag at rus.uni-stuttgart.de  Wed Nov 18 13:09:50 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 18:09:50 +0000 (UTC)
Subject: handling of non-ASCII filenames?
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
 <mailman.417.1447865700.16136.python-list@python.org>
Message-ID: <n2iete$js9$1@news2.informatik.uni-stuttgart.de>

Chris Angelico <rosuav at gmail.com> wrote:

> > As I am Python newbie I have not quite understood the Python character
> > encoding scheme :-}
> >
> > Where can I find a good introduction of this topic?
> 
> Here are a couple of articles on the basics of Unicode:
> 
> http://www.joelonsoftware.com/articles/Unicode.html

I do Unicode programming for over 20 years. So, I do have a basic
understanding of it. I am just new to Python.


> http://nedbatchelder.com/text/unipain.html

Thanks. I will read it.


> If you can use Python 3

I cannot use it, because the Python compiler pyinstaller does not work
with it on Windows:

S:\python>pyinstaller.exe --onefile tk.py
Traceback (most recent call last):
  File "C:\Python35\Scripts\pyinstaller-script.py", line 9, in <module>
    load_entry_point('PyInstaller==3.0', 'console_scripts', 'pyinstaller')()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 558, in l
oad_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2682, in
load_entry_point
    return ep.load()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2355, in
load
    return self.resolve()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2361, in
resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "c:\python35\lib\site-packages\PyInstaller\__main__.py", line 21, in <mod
ule>
    import PyInstaller.building.build_main
  File "c:\python35\lib\site-packages\PyInstaller\building\build_main.py", line
31, in <module>
    from ..depend import bindepend
  File "c:\python35\lib\site-packages\PyInstaller\depend\bindepend.py", line 40,
 in <module>
    from ..utils.win32.winmanifest import RT_MANIFEST
  File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winmanifest.py", l
ine 97, in <module>
    from PyInstaller.utils.win32 import winresource
  File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winresource.py", l
ine 20, in <module>
    import pywintypes
  File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 124, in <mo
dule>
    __import_pywin32_system_module__("pywintypes", globals())
  File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 64, in __im
port_pywin32_system_module__
    import _win32sysloader
ImportError: DLL load failed: The specified module could not be found.


With python 2.7, pyinstaller runs without problems.



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From eryksun at gmail.com  Wed Nov 18 13:24:08 2015
From: eryksun at gmail.com (eryksun)
Date: Wed, 18 Nov 2015 12:24:08 -0600
Subject: non-blocking getkey?
In-Reply-To: <n2hfe1$n3l$1@dont-email.me>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me>
Message-ID: <CACL+1asDSHKsh5emvnDQk6fH7hm-Qe6LGXvhQ7mevONHkowu0Q@mail.gmail.com>

On Wed, Nov 18, 2015 at 3:14 AM, Christian Gollwitzer <auriocus at gmx.de> wrote:
> The standard terminal on Windows is very ugly, can't resize the width, and
> pasting works only if you right-click -> paste.

The console UI is improved in Windows 10:
http://blogs.windows.com/buildingapps/2014/10/07/console-improvements-in-the-windows-10-technical-preview


From lac at openend.se  Wed Nov 18 14:30:34 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 18 Nov 2015 20:30:34 +0100
Subject: Mapping between python packages and distro packages?
In-Reply-To: <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>
References: <20151118032903.GA8040@sg1> <85vb90c4fv.fsf@benfinney.id.au>
 <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>
Message-ID: <201511181930.tAIJUYUc017056@fido.openend.se>

In a message of Wed, 18 Nov 2015 17:44:51 +1100, Chris Angelico writes:

>I don't know how the program would detect it, but I'd be thinking "the
>one where 'sudo apt-get install PACKAGENAME' gets the same code that
>'pip install THING' gets". In a lot of cases, PACKAGENAME will simply
>be python-THING or python3-THING, eg python3-sqlalchemy,
>python3-scipy, python3-bs4; as a human, that's what I'd try first. But
>having a program recognize this would be hugely beneficial.
>
>ChrisA

The problem is that this may not exist.  Debian developers, when faced
with a python package, may decide to break it up into several pieces,
and make several debian packagages.  If you want the same functionality
you have to load all of the debian packages, which of course involves
finding out what they are.

apt-cache search <PyPi name> works reasonably well, as long as you are
willing to put up with some false hits.  And it assumes you have a debian
system handy, of course.

Laura


From anthony at cajuntechie.org  Wed Nov 18 15:01:52 2015
From: anthony at cajuntechie.org (Anthony Papillion)
Date: Wed, 18 Nov 2015 14:01:52 -0600
Subject: How to create a folder using IMAPLib?
Message-ID: <564CD930.9000005@cajuntechie.org>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

I'm writing a program to help migrate mail from one host to another
with a few special circumstances. I'm able to get a list off of the
source IMAP server using the .list() command but I'm not quite sure
how to create a folder on the target machine.

Does anyone know how to create a folder using IMAPlib?

Thanks,
Anthony

- -- 
Phone:          1.845.666.1114
Skype:          cajuntechie
PGP Key:        0x028ADF7453B04B15
Fingerprint:    C5CE E687 DDC2 D12B 9063  56EA 028A DF74 53B0 4B15

-----BEGIN PGP SIGNATURE-----

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8UAGdPsn1LQ51BVDLaZ4
=77Lm
-----END PGP SIGNATURE-----



From rosuav at gmail.com  Wed Nov 18 15:24:06 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 07:24:06 +1100
Subject: Mapping between python packages and distro packages?
In-Reply-To: <201511181930.tAIJUYUc017056@fido.openend.se>
References: <20151118032903.GA8040@sg1> <85vb90c4fv.fsf@benfinney.id.au>
 <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>
 <201511181930.tAIJUYUc017056@fido.openend.se>
Message-ID: <CAPTjJmroZ4x7xxMpnWBWTsrn0nfD=U_dSaOWSPQ11fGOrdnT_A@mail.gmail.com>

On Thu, Nov 19, 2015 at 6:30 AM, Laura Creighton <lac at openend.se> wrote:
> apt-cache search <PyPi name> works reasonably well, as long as you are
> willing to put up with some false hits.  And it assumes you have a debian
> system handy, of course.

I suspect the most common case is "how can I get this on _this exact
system_", which isn't too hard; but the next most common case is "I
need to tell my friend how to get it on his/her system", which leaves
me sometimes wondering what the equivalent RPM for some DEB is, or
what sort of support there is for Program X on RHEL Y. So it would be
really nice if there were some straight-forward way to recognize these
equivalencies... but I doubt there is :(

ChrisA


From rosuav at gmail.com  Wed Nov 18 15:29:24 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 07:29:24 +1100
Subject: handling of non-ASCII filenames?
In-Reply-To: <n2iete$js9$1@news2.informatik.uni-stuttgart.de>
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
 <mailman.417.1447865700.16136.python-list@python.org>
 <n2iete$js9$1@news2.informatik.uni-stuttgart.de>
Message-ID: <CAPTjJmoEgU-uyQ=AbWc+dHBK=mbPEBY0dNaZFu=TJ0u-x1syxA@mail.gmail.com>

On Thu, Nov 19, 2015 at 5:09 AM, Ulli Horlacher
<framstag at rus.uni-stuttgart.de> wrote:
> Chris Angelico <rosuav at gmail.com> wrote:
>
>> > As I am Python newbie I have not quite understood the Python character
>> > encoding scheme :-}
>> >
>> > Where can I find a good introduction of this topic?
>>
>> Here are a couple of articles on the basics of Unicode:
>>
>> http://www.joelonsoftware.com/articles/Unicode.html
>
> I do Unicode programming for over 20 years. So, I do have a basic
> understanding of it. I am just new to Python.

Ah, okay. When you said you didn't understand the character encoding
scheme, I thought you meant Unicode itself. In any case, I make no
apology for recommending those two articles to people... at very worst
you already know that stuff :)

>> http://nedbatchelder.com/text/unipain.html
>
> Thanks. I will read it.

That's a great talk, and has the coolness of having zero pictures on
its slides. I love it.

>> If you can use Python 3
>
> I cannot use it, because the Python compiler pyinstaller does not work
> with it on Windows:
>
> S:\python>pyinstaller.exe --onefile tk.py
> Traceback (most recent call last):
>   File "C:\Python35\Scripts\pyinstaller-script.py", line 9, in <module>
>     load_entry_point('PyInstaller==3.0', 'console_scripts', 'pyinstaller')()
>   File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 558, in l
> oad_entry_point
>     return get_distribution(dist).load_entry_point(group, name)
>   File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2682, in
> load_entry_point
>     return ep.load()
>   File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2355, in
> load
>     return self.resolve()
>   File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2361, in
> resolve
>     module = __import__(self.module_name, fromlist=['__name__'], level=0)
>   File "c:\python35\lib\site-packages\PyInstaller\__main__.py", line 21, in <mod
> ule>
>     import PyInstaller.building.build_main
>   File "c:\python35\lib\site-packages\PyInstaller\building\build_main.py", line
> 31, in <module>
>     from ..depend import bindepend
>   File "c:\python35\lib\site-packages\PyInstaller\depend\bindepend.py", line 40,
>  in <module>
>     from ..utils.win32.winmanifest import RT_MANIFEST
>   File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winmanifest.py", l
> ine 97, in <module>
>     from PyInstaller.utils.win32 import winresource
>   File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winresource.py", l
> ine 20, in <module>
>     import pywintypes
>   File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 124, in <mo
> dule>
>     __import_pywin32_system_module__("pywintypes", globals())
>   File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 64, in __im
> port_pywin32_system_module__
>     import _win32sysloader
> ImportError: DLL load failed: The specified module could not be found.
>
>
> With python 2.7, pyinstaller runs without problems.

Hmm. That's a separate consideration. If you take a step back and ask
the broader question "How can I package my Python 3.5 script into a
.exe file?", I'm pretty sure there is an answer; maybe pyinstaller
isn't the way to do it. (I'm not an expert on exe file production.)
Does your script run happily in 3.5 if it isn't packaged into an exe?

ChrisA


From rosuav at gmail.com  Wed Nov 18 15:35:36 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 07:35:36 +1100
Subject: How to create a folder using IMAPLib?
In-Reply-To: <564CD930.9000005@cajuntechie.org>
References: <564CD930.9000005@cajuntechie.org>
Message-ID: <CAPTjJmqDBicF6+xLvFS+D8ow5e3Tmx+xx=n7MMhDvJkXVvKVGw@mail.gmail.com>

On Thu, Nov 19, 2015 at 7:01 AM, Anthony Papillion
<anthony at cajuntechie.org> wrote:
> I'm writing a program to help migrate mail from one host to another
> with a few special circumstances. I'm able to get a list off of the
> source IMAP server using the .list() command but I'm not quite sure
> how to create a folder on the target machine.
>
> Does anyone know how to create a folder using IMAPlib?

They're called "mailboxes", which I'll admit is not the most obvious
name, but imaplib is following the IMAP spec here. You can create them
with .create() and delete them with .delete().

ChrisA


From rxjwg98 at gmail.com  Wed Nov 18 16:08:11 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 13:08:11 -0800 (PST)
Subject: What is a function parameter =[] for?
Message-ID: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>

Hi,

I have tried the below function and find that it can remember the previous
setting value to 'val'. I think the second parameter has something on this 
effect, but I don't know the name and function of '=[]' in this application.

Could you explain a little to me?
Thanks,


def eList(val, list0=[]):
    list0.append(val)
    return list0
list1 = eList(12)
list1 = eList('a')


From random832 at fastmail.com  Wed Nov 18 16:38:30 2015
From: random832 at fastmail.com (Random832)
Date: Wed, 18 Nov 2015 16:38:30 -0500
Subject: How can I export data from a website and write the contents to a
 text file?
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
Message-ID: <87si43kmy1.fsf@fastmail.com>

ryguy7272 <ryanshuell at gmail.com> writes:
> text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")

Remove the "b" from this line. This is causing it to omit the
platform-specific translation of "\n", which means some Windows
applications will not recognize the line endings.



From lac at openend.se  Wed Nov 18 16:58:47 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 18 Nov 2015 22:58:47 +0100
Subject: How to create a folder using IMAPLib?
In-Reply-To: <CAPTjJmqDBicF6+xLvFS+D8ow5e3Tmx+xx=n7MMhDvJkXVvKVGw@mail.gmail.com>
References: <564CD930.9000005@cajuntechie.org>
 <CAPTjJmqDBicF6+xLvFS+D8ow5e3Tmx+xx=n7MMhDvJkXVvKVGw@mail.gmail.com>
Message-ID: <201511182158.tAILwlNj027195@fido.openend.se>

In a message of Thu, 19 Nov 2015 07:35:36 +1100, Chris Angelico writes:
>On Thu, Nov 19, 2015 at 7:01 AM, Anthony Papillion
><anthony at cajuntechie.org> wrote:
>> I'm writing a program to help migrate mail from one host to another
>> with a few special circumstances. I'm able to get a list off of the
>> source IMAP server using the .list() command but I'm not quite sure
>> how to create a folder on the target machine.
>>
>> Does anyone know how to create a folder using IMAPlib?
>
>They're called "mailboxes", which I'll admit is not the most obvious
>name, but imaplib is following the IMAP spec here. You can create them
>with .create() and delete them with .delete().
>
>ChrisA
>-- 
>https://mail.python.org/mailman/listinfo/python-list

Sample code here:
https://pymotw.com/2/imaplib/

Laura


From gordon at panix.com  Wed Nov 18 17:05:19 2015
From: gordon at panix.com (John Gordon)
Date: Wed, 18 Nov 2015 22:05:19 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
Message-ID: <n2ismv$jdd$1@reader1.panix.com>

In <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862 at googlegroups.com> fl <rxjwg98 at gmail.com> writes:

> Hi,

> I have tried the below function and find that it can remember the previous
> setting value to 'val'. I think the second parameter has something on this 
> effect, but I don't know the name and function of '=[]' in this application.

> Could you explain a little to me?
> Thanks,

> def eList(val, list0=[]):
>     list0.append(val)
>     return list0
> list1 = eList(12)
> list1 = eList('a')

That is a default parameter.  If eList() is called without an argument for
list0, it will use [] as the default value.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From ian.g.kelly at gmail.com  Wed Nov 18 17:11:43 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 18 Nov 2015 15:11:43 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
Message-ID: <CALwzid=Dr6NoF0qPjM3m1ZqVhprUoDeEOV9eUWXwcjdM=pDPYA@mail.gmail.com>

On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:
> Hi,
>
> I have tried the below function and find that it can remember the previous
> setting value to 'val'. I think the second parameter has something on this
> effect, but I don't know the name and function of '=[]' in this application.
>
> Could you explain a little to me?
> Thanks,
>
>
> def eList(val, list0=[]):
>     list0.append(val)
>     return list0
> list1 = eList(12)
> list1 = eList('a')

The list0 parameter has a default value, which is [], an initially
empty list. The default value is evaluated when the function is
defined, not when it is called, so the same list object is used each
time and changes to the list are consequently retained between calls.


From invalid at invalid.invalid  Wed Nov 18 17:33:11 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Wed, 18 Nov 2015 22:33:11 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
Message-ID: <n2iub7$vo$1@reader1.panix.com>

On 2015-11-18, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:

>> def eList(val, list0=[]):

> The list0 parameter has a default value, which is [], an initially
> empty list. The default value is evaluated when the function is
> defined, not when it is called, so the same list object is used each
> time and changes to the list are consequently retained between calls.

One might consider this a way to have a local varible inside a
function that's "static" a-la C.  However, one probably oughtn't.

-- 
Grant Edwards               grant.b.edwards        Yow! Gibble, Gobble, we
                                  at               ACCEPT YOU ...
                              gmail.com            


From framstag at rus.uni-stuttgart.de  Wed Nov 18 17:37:59 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 22:37:59 +0000 (UTC)
Subject: handling of non-ASCII filenames?
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
 <mailman.417.1447865700.16136.python-list@python.org>
 <n2iete$js9$1@news2.informatik.uni-stuttgart.de>
 <mailman.425.1447878573.16136.python-list@python.org>
Message-ID: <n2iuk7$o1n$1@news2.informatik.uni-stuttgart.de>

Chris Angelico <rosuav at gmail.com> wrote:

> >> If you can use Python 3
> >
> > I cannot use it, because the Python compiler pyinstaller does not work
> > with it on Windows:
> >
> > S:\python>pyinstaller.exe --onefile tk.py
> > Traceback (most recent call last):
> >   File "C:\Python35\Scripts\pyinstaller-script.py", line 9, in <module>
> >     load_entry_point('PyInstaller==3.0', 'console_scripts', 'pyinstaller')()
> >   File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 558, in l
> > oad_entry_point
(...)
> >
> > With python 2.7, pyinstaller runs without problems.
> 
> Hmm. That's a separate consideration. If you take a step back and ask
> the broader question "How can I package my Python 3.5 script into a
> .exe file?", I'm pretty sure there is an answer; maybe pyinstaller
> isn't the way to do it. (I'm not an expert on exe file production.)

pyinstaller works without any problems with Python 2.7.10


> Does your script run happily in 3.5 if it isn't packaged into an exe?

Yes.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rxjwg98 at gmail.com  Wed Nov 18 17:38:31 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 14:38:31 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.429.1447884751.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
Message-ID: <cea77860-b3d0-4ac0-9803-82ec270dfdb4@googlegroups.com>

On Wednesday, November 18, 2015 at 5:12:44 PM UTC-5, Ian wrote:
> On Wed, Nov 18, 2015 at 2:08 PM, fl <com> wrote:
> > Hi,
> >
> > I have tried the below function and find that it can remember the previous
> > setting value to 'val'. I think the second parameter has something on this
> > effect, but I don't know the name and function of '=[]' in this application.
> >
> > Could you explain a little to me?
> > Thanks,
> >
> >
> > def eList(val, list0=[]):
> >     list0.append(val)
> >     return list0
> > list1 = eList(12)
> > list1 = eList('a')
> 
> The list0 parameter has a default value, which is [], an initially
> empty list. The default value is evaluated when the function is
> defined, not when it is called, so the same list object is used each
> time and changes to the list are consequently retained between calls.

Thanks. The amazing thing to me is that the following two line codes:
list1 = eList(12) 
list2 = eList('a')

will have both list1 and list2 the same cascaded values:

list1
Out[2]: [12, 'a']

list2
Out[3]: [12, 'a']

I have known object concept in Python.
1. Why do they have the same list value?
 Function eList must be for this purpose?
2. If I want to have two separate lists, how to avoid the above result?
 Function eList is not for this purpose?

Thanks again.


From framstag at rus.uni-stuttgart.de  Wed Nov 18 17:46:17 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 18 Nov 2015 22:46:17 +0000 (UTC)
Subject: pyinstaller and Python 3.5 on Windows?
Message-ID: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>

To run my Python programs on other Windows systems without a Python
installation I must create standalone Windows executables.

pyinstaller runs without any problems with Python 2.7.10 on Windows 7, but
with Python 3.5 I get:

S:\python>pyinstaller.exe --onefile tk.py
Traceback (most recent call last):
  File "C:\Python35\Scripts\pyinstaller-script.py", line 9, in <module>
    load_entry_point('PyInstaller==3.0', 'console_scripts', 'pyinstaller')()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 558, in l
oad_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2682, in
load_entry_point
    return ep.load()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2355, in
load
    return self.resolve()
  File "c:\python35\lib\site-packages\pkg_resources\__init__.py", line 2361, in
resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "c:\python35\lib\site-packages\PyInstaller\__main__.py", line 21, in <mod
ule>
    import PyInstaller.building.build_main
  File "c:\python35\lib\site-packages\PyInstaller\building\build_main.py", line
31, in <module>
    from ..depend import bindepend
  File "c:\python35\lib\site-packages\PyInstaller\depend\bindepend.py", line 40,
 in <module>
    from ..utils.win32.winmanifest import RT_MANIFEST
  File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winmanifest.py", l
ine 97, in <module>
    from PyInstaller.utils.win32 import winresource
  File "c:\python35\lib\site-packages\PyInstaller\utils\win32\winresource.py", l
ine 20, in <module>
    import pywintypes
  File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 124, in <mo
dule>
    __import_pywin32_system_module__("pywintypes", globals())
  File "c:\python35\lib\site-packages\win32\lib\pywintypes.py", line 64, in __im
port_pywin32_system_module__
    import _win32sysloader
ImportError: DLL load failed: The specified module could not be found.


Is there a solution available?



-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From ian.g.kelly at gmail.com  Wed Nov 18 17:47:00 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 18 Nov 2015 15:47:00 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <cea77860-b3d0-4ac0-9803-82ec270dfdb4@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <cea77860-b3d0-4ac0-9803-82ec270dfdb4@googlegroups.com>
Message-ID: <CALwzidkDpySq5h4sCr+VvH1MbDDX71D2DG04MekXZfuLJSn0KQ@mail.gmail.com>

On Wed, Nov 18, 2015 at 3:38 PM, fl <rxjwg98 at gmail.com> wrote:
> On Wednesday, November 18, 2015 at 5:12:44 PM UTC-5, Ian wrote:
>> On Wed, Nov 18, 2015 at 2:08 PM, fl <com> wrote:
>> > Hi,
>> >
>> > I have tried the below function and find that it can remember the previous
>> > setting value to 'val'. I think the second parameter has something on this
>> > effect, but I don't know the name and function of '=[]' in this application.
>> >
>> > Could you explain a little to me?
>> > Thanks,
>> >
>> >
>> > def eList(val, list0=[]):
>> >     list0.append(val)
>> >     return list0
>> > list1 = eList(12)
>> > list1 = eList('a')
>>
>> The list0 parameter has a default value, which is [], an initially
>> empty list. The default value is evaluated when the function is
>> defined, not when it is called, so the same list object is used each
>> time and changes to the list are consequently retained between calls.
>
> Thanks. The amazing thing to me is that the following two line codes:
> list1 = eList(12)
> list2 = eList('a')
>
> will have both list1 and list2 the same cascaded values:
>
> list1
> Out[2]: [12, 'a']
>
> list2
> Out[3]: [12, 'a']
>
> I have known object concept in Python.
> 1. Why do they have the same list value?
>  Function eList must be for this purpose?

Because eList returns list0, and as explained above list0 is the same
list in both calls. Therefore list1 and list2 are the same list.

> 2. If I want to have two separate lists, how to avoid the above result?
>  Function eList is not for this purpose?

The usual advice is to not use a mutable object as the default value.
If you want the default to be an empty list, it's usually better set
it to None and then make it an empty list if the value is None. For
example:

def eList(val, list0=None):
    if list0 is None:
        list0 = []
    list0.append(val)
    return list0


From rxjwg98 at gmail.com  Wed Nov 18 17:48:57 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 14:48:57 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <cea77860-b3d0-4ac0-9803-82ec270dfdb4@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <cea77860-b3d0-4ac0-9803-82ec270dfdb4@googlegroups.com>
Message-ID: <49ad34bd-0943-4ac0-92e7-4636d2f9d447@googlegroups.com>

On Wednesday, November 18, 2015 at 5:38:45 PM UTC-5, fl wrote:
> On Wednesday, November 18, 2015 at 5:12:44 PM UTC-5, Ian wrote:
> > On Wed, Nov 18, 2015 at 2:08 PM, fl <com> wrote:
> > > Hi,
> > >
> > > I have tried the below function and find that it can remember the previous
> > > setting value to 'val'. I think the second parameter has something on this
> > > effect, but I don't know the name and function of '=[]' in this application.
> > >
> > > Could you explain a little to me?
> > > Thanks,
> > >
> > >
> > > def eList(val, list0=[]):
> > >     list0.append(val)
> > >     return list0
> > > list1 = eList(12)
> > > list1 = eList('a')
> > 
> > The list0 parameter has a default value, which is [], an initially
> > empty list. The default value is evaluated when the function is
> > defined, not when it is called, so the same list object is used each
> > time and changes to the list are consequently retained between calls.
> 
> Thanks. The amazing thing to me is that the following two line codes:
> list1 = eList(12) 
> list2 = eList('a')
> 
> will have both list1 and list2 the same cascaded values:
> 
> list1
> Out[2]: [12, 'a']
> 
> list2
> Out[3]: [12, 'a']
> 
> I have known object concept in Python.
> 1. Why do they have the same list value?
>  Function eList must be for this purpose?
> 2. If I want to have two separate lists, how to avoid the above result?
>  Function eList is not for this purpose?
> 
> Thanks again.

After several trials, I find that the cascade list is caused by the second
function parameter absent. It is interesting. Thanks.


From bc at freeuk.com  Wed Nov 18 18:14:12 2015
From: bc at freeuk.com (BartC)
Date: Wed, 18 Nov 2015 23:14:12 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.429.1447884751.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
Message-ID: <n2j0k4$up4$1@dont-email.me>

On 18/11/2015 22:11, Ian Kelly wrote:
> On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:
>> Hi,
>>
>> I have tried the below function and find that it can remember the previous
>> setting value to 'val'. I think the second parameter has something on this
>> effect, but I don't know the name and function of '=[]' in this application.
>>
>> Could you explain a little to me?
>> Thanks,
>>
>>
>> def eList(val, list0=[]):
>>      list0.append(val)
>>      return list0
>> list1 = eList(12)
>> list1 = eList('a')
>
> The list0 parameter has a default value, which is [], an initially
> empty list. The default value is evaluated when the function is
> defined, not when it is called, so the same list object is used each
> time and changes to the list are consequently retained between calls.

That is really bizarre behaviour.

So, looking at some source code, a default value for certain types is 
only certain to be that value for the very first call of that function?

 > The default value is evaluated when the function is
 > defined, not when it is called

Given the amount of pointless dynamic stuff that goes on in Python, I'm 
surprised they've overlooked this one!

It seems simple enough to me to check for a missing parameter, and to 
assign whatever default value was designated ([] in this case). (How 
does the default mechanism work now?)

-- 
Bartc



From vincent at vincentdavis.net  Wed Nov 18 18:18:28 2015
From: vincent at vincentdavis.net (Vincent Davis)
Date: Wed, 18 Nov 2015 16:18:28 -0700
Subject: Public key encryption example.
Message-ID: <CALyJZZUEV311wZ5+QGkmfW3o=FsjDBAekAXW1FZ13LeeLtHK_A@mail.gmail.com>

This might be a "Let me Google that for you question", I tried.
I am looking for the "simplest" example of sending(encrypting) and
receiving(decrypting) using public key encryption. I am think of something
along the lines of having all the keys in local files and saving and
reading the message from a local file.

Possibly using cryptography library elliptic-curve
https://cryptography.io/en/latest/hazmat/primitives/asymmetric/ec/#elliptic-curve-signature-algorithms

Surly there is an example out there?

Vincent Davis


From rosuav at gmail.com  Wed Nov 18 18:22:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 10:22:04 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2j0k4$up4$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
Message-ID: <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>

On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
> On 18/11/2015 22:11, Ian Kelly wrote:
>>
>> On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> I have tried the below function and find that it can remember the
>>> previous
>>> setting value to 'val'. I think the second parameter has something on
>>> this
>>> effect, but I don't know the name and function of '=[]' in this
>>> application.
>>>
>>> Could you explain a little to me?
>>> Thanks,
>>>
>>>
>>> def eList(val, list0=[]):
>>>      list0.append(val)
>>>      return list0
>>> list1 = eList(12)
>>> list1 = eList('a')
>>
>>
>> The list0 parameter has a default value, which is [], an initially
>> empty list. The default value is evaluated when the function is
>> defined, not when it is called, so the same list object is used each
>> time and changes to the list are consequently retained between calls.
>
>
> That is really bizarre behaviour.
>
> So, looking at some source code, a default value for certain types is only
> certain to be that value for the very first call of that function?

On the contrary, it is certain always to be that exact object.

>> The default value is evaluated when the function is
>> defined, not when it is called
>
> Given the amount of pointless dynamic stuff that goes on in Python, I'm
> surprised they've overlooked this one!
>
> It seems simple enough to me to check for a missing parameter, and to assign
> whatever default value was designated ([] in this case). (How does the
> default mechanism work now?)

It's exactly the way Ian described it. Functions are defined, not
declared - it's an executable statement. When the 'def' statement is
reached, the expressions in the argument defaults get evaluated, and
the results get saved into the function's attributes:

>>> def demo(factory):
...     def func(x=factory()):
...         x.append("Hello!")
...         return x
...     return func
...
>>> def make_list():
...     print("I'm making a list!")
...     return []
...
>>> f1 = demo(make_list)
I'm making a list!
>>> f2 = demo(make_list)
I'm making a list!
>>> f3 = demo(make_list)
I'm making a list!
>>> f1()
['Hello!']
>>> f1()
['Hello!', 'Hello!']
>>> f1()
['Hello!', 'Hello!', 'Hello!']
>>> f2()
['Hello!']
>>> f2()
['Hello!', 'Hello!']
>>> f3()
['Hello!']
>>> f1.__defaults__
(['Hello!', 'Hello!', 'Hello!'],)
>>> id(f1())
140470001247688
>>> id(f1())
140470001247688
>>> id(f1())
140470001247688
>>> id(f1())
140470001247688
>>> id(f1())
140470001247688
>>> id(f1.__defaults__[0])
140470001247688

If you want the expression (eg the empty list display) to be evaluated
every time the body of the function is executed, you put it into the
body of the function. There is no magic here.

ChrisA


From no.email at nospam.invalid  Wed Nov 18 18:56:01 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Wed, 18 Nov 2015 15:56:01 -0800
Subject: Public key encryption example.
References: <mailman.431.1447888735.16136.python-list@python.org>
Message-ID: <87vb8ylv5a.fsf@nightsong.com>

Vincent Davis <vincent at vincentdavis.net> writes:
> I am looking for the "simplest" example of sending(encrypting) and
> receiving(decrypting) using public key encryption. I am think of something
> along the lines of having all the keys in local files and saving and
> reading the message from a local file.

It's very easy to make mistakes doing stuff like that.  Your simplest
bet is to shell out to GPG or something comparable.


From ian.g.kelly at gmail.com  Wed Nov 18 19:02:39 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 18 Nov 2015 17:02:39 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
Message-ID: <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>

On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
>> So, looking at some source code, a default value for certain types is only
>> certain to be that value for the very first call of that function?
>
> On the contrary, it is certain always to be that exact object.

"Certain" may be a bit overly strong.

>>> def f(x=42):
...   return x
...
>>> f()
42
>>> f.__defaults__ = (43,)
>>> f()
43


From rosuav at gmail.com  Wed Nov 18 19:04:00 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 11:04:00 +1100
Subject: Public key encryption example.
In-Reply-To: <87vb8ylv5a.fsf@nightsong.com>
References: <mailman.431.1447888735.16136.python-list@python.org>
 <87vb8ylv5a.fsf@nightsong.com>
Message-ID: <CAPTjJmr8mmDU7xWgeMZUaxb8rHjYO=Vmk5_5_-9XynezpVM8Yg@mail.gmail.com>

On Thu, Nov 19, 2015 at 10:56 AM, Paul Rubin <no.email at nospam.invalid> wrote:
> Vincent Davis <vincent at vincentdavis.net> writes:
>> I am looking for the "simplest" example of sending(encrypting) and
>> receiving(decrypting) using public key encryption. I am think of something
>> along the lines of having all the keys in local files and saving and
>> reading the message from a local file.
>
> It's very easy to make mistakes doing stuff like that.  Your simplest
> bet is to shell out to GPG or something comparable.

It's not that hard to pull up a library. I've never done it in Python, though.

ChrisA


From rxjwg98 at gmail.com  Wed Nov 18 19:05:37 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 16:05:37 -0800 (PST)
Subject: Could you explain why the following generates 4 same elements list?
Message-ID: <3f1eecc8-e23d-4f86-abf8-38044939d085@googlegroups.com>

Hi,

I cannot reason out why the code:
////////
def mpl():
    return [lambda x : i * x for i in range(4)]
    
print [m(2) for m in mpl()]
/////////

has result:

[6, 6, 6, 6]


I have tried to simplify the above code to an easy understanding form,
but fails. Either the modified code does not work, or it does not show
relation to the original code.
 
Could you explore it a little for me to understand it easier?

Thanks in advance.


From PointedEars at web.de  Wed Nov 18 19:13:28 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Thu, 19 Nov 2015 01:13:28 +0100
Subject: pyinstaller and Python 3.5 on Windows?
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
Message-ID: <16273698.Ox6ucYQkhb@PointedEars.de>

Ulli Horlacher wrote:

> To run my Python programs on other Windows systems without a Python
> installation I must create standalone Windows executables.
> 
> pyinstaller runs without any problems with Python 2.7.10 on Windows 7, but
> with Python 3.5 I get:
> 
> [b0rked stack trace]
> 
> Is there a solution available?

Maybe.  It would help if you posted something easier readable.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From rosuav at gmail.com  Wed Nov 18 19:14:49 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 11:14:49 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
Message-ID: <CAPTjJmpOCjJwFSH5ogSVf-VBm77T6u5Eq+=rFXmH6_XwKWSqGA@mail.gmail.com>

On Thu, Nov 19, 2015 at 11:02 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
>>> So, looking at some source code, a default value for certain types is only
>>> certain to be that value for the very first call of that function?
>>
>> On the contrary, it is certain always to be that exact object.
>
> "Certain" may be a bit overly strong.
>
>>>> def f(x=42):
> ...   return x
> ...
>>>> f()
> 42
>>>> f.__defaults__ = (43,)
>>>> f()
> 43

I'll raise you one.

>>> def f(x=42):
...     return x
...
>>> f()
42
>>> import ctypes
>>> ctypes.c_int.from_address(id(43)+ ctypes.sizeof(ctypes.c_size_t) + ctypes.sizeof(ctypes.c_voidp)).value=42
>>> f.__defaults__ = (43,)
>>> f()
42
>>>

Nothing is certain in Python. And two wrongs can make a... hmm... no,
this is not a right. It is not a privilege either. It is a dastardly
trick played on people's minds.

ChrisA


From rxjwg98 at gmail.com  Wed Nov 18 19:34:50 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 16:34:50 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.435.1447892092.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
 <mailman.435.1447892092.16136.python-list@python.org>
Message-ID: <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>

On Wednesday, November 18, 2015 at 7:15:05 PM UTC-5, Chris Angelico wrote:
> On Thu, Nov 19, 2015 at 11:02 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> > On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <rosuav at gmail.com> wrote:
> >> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
> >>> So, looking at some source code, a default value for certain types is only
> >>> certain to be that value for the very first call of that function?
> >>
> >> On the contrary, it is certain always to be that exact object.
> >
> > "Certain" may be a bit overly strong.
> >
> >>>> def f(x=42):
> > ...   return x
> > ...
> >>>> f()
> > 42
> >>>> f.__defaults__ = (43,)
> >>>> f()
> > 43
> 
> I'll raise you one.
> 
> >>> def f(x=42):
> ...     return x
> ...
> >>> f()
> 42
> >>> import ctypes
> >>> ctypes.c_int.from_address(id(43)+ ctypes.sizeof(ctypes.c_size_t) + ctypes.sizeof(ctypes.c_voidp)).value=42
> >>> f.__defaults__ = (43,)
> >>> f()
> 42
> >>>
> 
> Nothing is certain in Python. And two wrongs can make a... hmm... no,
> this is not a right. It is not a privilege either. It is a dastardly
> trick played on people's minds.
> 
> ChrisA

After I try with

list1 = eList(12, [2])

and

list1 = eList(12)

it gives me new surprises. Even though I delete list1, the subsequent
list1 = eList(12)
will remember the number of '12' of the previous sequence. This is my new
question: What does 'del' do? It does not look like a thorough list deletion
 from the effect.

Thanks,

.....................
list1 = eList(12, [2])

list1
Out[57]: [2, 12]

list1 = eList(12)

list1
Out[59]: [12, 12, 12]

list1 = eList(12, [2])

list1
Out[61]: [2, 12]

list1 = eList(12, [2])

list1
Out[63]: [2, 12]

list1 = eList(12, [2])

list1
Out[65]: [2, 12]

list1 = eList(12)

list1
Out[67]: [12, 12, 12, 12]

list1 = eList(12)

list1
Out[69]: [12, 12, 12, 12, 12]

list1 = eList(12, [2])

list1
Out[71]: [2, 12]

list1 = eList(12)

list1
Out[73]: [12, 12, 12, 12, 12, 12]

del list1

list1 = eList(12, [2])

list1 = eList(12)

list1
Out[77]: [12, 12, 12, 12, 12, 12, 12]



From ian.g.kelly at gmail.com  Wed Nov 18 19:47:51 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 18 Nov 2015 17:47:51 -0700
Subject: Could you explain why the following generates 4 same elements
 list?
In-Reply-To: <3f1eecc8-e23d-4f86-abf8-38044939d085@googlegroups.com>
References: <3f1eecc8-e23d-4f86-abf8-38044939d085@googlegroups.com>
Message-ID: <CALwzidm7JFVHRuwpWNot5FHKV6YOWzESkOFG09BKZUmqpxSn3A@mail.gmail.com>

On Wed, Nov 18, 2015 at 5:05 PM, fl <rxjwg98 at gmail.com> wrote:
> Hi,
>
> I cannot reason out why the code:
> ////////
> def mpl():
>     return [lambda x : i * x for i in range(4)]
>
> print [m(2) for m in mpl()]
> /////////
>
> has result:
>
> [6, 6, 6, 6]
>
>
> I have tried to simplify the above code to an easy understanding form,
> but fails. Either the modified code does not work, or it does not show
> relation to the original code.
>
> Could you explore it a little for me to understand it easier?

https://docs.python.org/3/faq/programming.html#why-do-lambdas-defined-in-a-loop-with-different-values-all-return-the-same-result


From ian.g.kelly at gmail.com  Wed Nov 18 19:52:33 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 18 Nov 2015 17:52:33 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
 <mailman.435.1447892092.16136.python-list@python.org>
 <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
Message-ID: <CALwzidm7HHNXuX6_EUJNzTDa-U8TZaPsOE+-eRzJKpBfStbWKw@mail.gmail.com>

On Wed, Nov 18, 2015 at 5:34 PM, fl <rxjwg98 at gmail.com> wrote:
> After I try with
>
> list1 = eList(12, [2])
>
> and
>
> list1 = eList(12)
>
> it gives me new surprises. Even though I delete list1, the subsequent
> list1 = eList(12)
> will remember the number of '12' of the previous sequence. This is my new
> question: What does 'del' do? It does not look like a thorough list deletion
>  from the effect.

It just deletes the variable list1, i.e. it unbinds the value from the
name. It does nothing at all to the list that was bound, as other
variables may still be bound to it.

The core issue is that the default value of your eList function is
always the same list. Assigning that list to a variable and then
unassigning it is not going to change that.


From python at mrabarnett.plus.com  Wed Nov 18 20:02:11 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 19 Nov 2015 01:02:11 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
 <mailman.435.1447892092.16136.python-list@python.org>
 <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
Message-ID: <564D1F93.7000902@mrabarnett.plus.com>

On 2015-11-19 00:34, fl wrote:
> On Wednesday, November 18, 2015 at 7:15:05 PM UTC-5, Chris Angelico wrote:
>> On Thu, Nov 19, 2015 at 11:02 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> > On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> >> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
>> >>> So, looking at some source code, a default value for certain types is only
>> >>> certain to be that value for the very first call of that function?
>> >>
>> >> On the contrary, it is certain always to be that exact object.
>> >
>> > "Certain" may be a bit overly strong.
>> >
>> >>>> def f(x=42):
>> > ...   return x
>> > ...
>> >>>> f()
>> > 42
>> >>>> f.__defaults__ = (43,)
>> >>>> f()
>> > 43
>>
>> I'll raise you one.
>>
>> >>> def f(x=42):
>> ...     return x
>> ...
>> >>> f()
>> 42
>> >>> import ctypes
>> >>> ctypes.c_int.from_address(id(43)+ ctypes.sizeof(ctypes.c_size_t) + ctypes.sizeof(ctypes.c_voidp)).value=42
>> >>> f.__defaults__ = (43,)
>> >>> f()
>> 42
>> >>>
>>
>> Nothing is certain in Python. And two wrongs can make a... hmm... no,
>> this is not a right. It is not a privilege either. It is a dastardly
>> trick played on people's minds.
>>
>> ChrisA
>
> After I try with
>
> list1 = eList(12, [2])
>
If you pass something into the parameter, the default isn't needed/used.

> and
>
> list1 = eList(12)
>
You're not passing anything into the parameter, so the default is used.

> it gives me new surprises. Even though I delete list1, the subsequent
> list1 = eList(12)
> will remember the number of '12' of the previous sequence. This is my new
> question: What does 'del' do? It does not look like a thorough list deletion
>   from the effect.
>
No, "del list1" doesn't delete the list, it deletes the name "list1".
The list still exists as the default parameter.

A default parameter is evaluated when the function is defined, and that
value exists as the default as long as the function exists.

If the value is mutable (can be modified), and you modify it, then the
function will see that modified value.



From ben+python at benfinney.id.au  Wed Nov 18 20:26:28 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 19 Nov 2015 12:26:28 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
 <mailman.435.1447892092.16136.python-list@python.org>
 <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
 <564D1F93.7000902@mrabarnett.plus.com>
Message-ID: <85oaeqdbjv.fsf@benfinney.id.au>

MRAB <python at mrabarnett.plus.com> writes:

> On 2015-11-19 00:34, fl wrote:
> > What does 'del' do? It does not look like a thorough list deletion
> > from the effect.
>
> No, "del list1" doesn't delete the list, it deletes the name "list1".
> The list still exists as the default parameter.

More generally, ?del? deletes a *reference*. Names are one kind of
reference; others include items in a collection such as a dict or set.

Deleting a reference *never* affects the value referred to.

However, once a value has no more references, the program can no longer
access it, so the Python machine is at liberty to delete the value
behind the scenes at some future point.

> A default parameter is evaluated when the function is defined, and
> that value exists as the default as long as the function exists.

So, because the function retains a reference to the value, the value
remains unaffected when you delete the reference ?list1?.

-- 
 \         ?True greatness is measured by how much freedom you give to |
  `\      others, not by how much you can coerce others to do what you |
_o__)                                               want.? ?Larry Wall |
Ben Finney



From bc at freeuk.com  Wed Nov 18 20:41:47 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 01:41:47 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.432.1447888928.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
Message-ID: <n2j98r$o9c$1@dont-email.me>

On 18/11/2015 23:22, Chris Angelico wrote:
> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
>> On 18/11/2015 22:11, Ian Kelly wrote:
>>>
>>> On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I have tried the below function and find that it can remember the
>>>> previous
>>>> setting value to 'val'. I think the second parameter has something on
>>>> this
>>>> effect, but I don't know the name and function of '=[]' in this
>>>> application.
>>>>
>>>> Could you explain a little to me?
>>>> Thanks,
>>>>
>>>>
>>>> def eList(val, list0=[]):
>>>>       list0.append(val)
>>>>       return list0
>>>> list1 = eList(12)
>>>> list1 = eList('a')
>>>
>>>
>>> The list0 parameter has a default value, which is [], an initially
>>> empty list. The default value is evaluated when the function is
>>> defined, not when it is called, so the same list object is used each
>>> time and changes to the list are consequently retained between calls.
>>
>>
>> That is really bizarre behaviour.
>>
>> So, looking at some source code, a default value for certain types is only
>> certain to be that value for the very first call of that function?
>
> On the contrary, it is certain always to be that exact object.

But, not the same value that appears as the default?

  >>> The default value is evaluated when the function is
>>> defined, not when it is called
>>
>> Given the amount of pointless dynamic stuff that goes on in Python, I'm
>> surprised they've overlooked this one!
>>
>> It seems simple enough to me to check for a missing parameter, and to assign
>> whatever default value was designated ([] in this case). (How does the
>> default mechanism work now?)
>
> It's exactly the way Ian described it. Functions are defined, not
> declared - it's an executable statement. When the 'def' statement is
> reached, the expressions in the argument defaults get evaluated, and
> the results get saved into the function's attributes:
....

Sorry, I didn't understand any of that. Let's try a simpler example like 
the OP's. There's this innocuous looking function that you are 
interested in calling:

  def fn(a=[]):
  #   print ("Function fn called with",a)
  |   a.append(10)
  |   return a

It appends a value to its argument and returns the result.

It looks like at first like, if called with no argument, it will return 
[10].

But what it actually returns depends on the entire call history since 
the program started executing, something you probably have no knowledge 
of and no control over. So if fn has previously been called a million 
times with no argument, then after this call:

  x=fn()

x contains a list of a million tens, not one. I'd say most people would 
be rather surprised by that.

I suspect those same people (unless they are experts in the murky 
corners of the language) would expect:

   x=fn()

when fn specifies a default argument of [], to be the same as writing:

   x=fn([])

and not be dependent on fn's entire call history.

Your solution of using:

   def fn(a=None):

is not really satisfactory. Partly because it now utilities two 
mechanisms for the default: first to get None, then some extra code to 
get []. But also it's no longer obvious how the function works and what 
the default is. At least, you can't tell from a glance at the start of 
the function that [] is the default.

-- 
Bartc




From rosuav at gmail.com  Wed Nov 18 20:59:18 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 12:59:18 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2j98r$o9c$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
Message-ID: <CAPTjJmp3N98ZmvSS-=NBzoQQOX5ojxG3GjkKrPB98_2-9nCv_A@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:41 PM, BartC <bc at freeuk.com> wrote:
> On 18/11/2015 23:22, Chris Angelico wrote:
>> On the contrary, it is certain always to be that exact object.
>
> But, not the same value that appears as the default?

Nope. Mutable objects are never guaranteed to retain the same values.
That's kinda the point.

> Sorry, I didn't understand any of that. Let's try a simpler example like the
> OP's. There's this innocuous looking function that you are interested in
> calling:
>
>  def fn(a=[]):
>  #   print ("Function fn called with",a)
>  |   a.append(10)
>  |   return a
>
> It appends a value to its argument and returns the result.
>
> It looks like at first like, if called with no argument, it will return
> [10].

If you want to think of function defaults as being values, then yes.
But they're not. They're objects.

> But what it actually returns depends on the entire call history since the
> program started executing, something you probably have no knowledge of and
> no control over. So if fn has previously been called a million times with no
> argument, then after this call:
>
>  x=fn()
>
> x contains a list of a million tens, not one. I'd say most people would be
> rather surprised by that.

So if you don't want them to be surprised by that, don't use mutable
default arguments and expect them to have specific values.

> I suspect those same people (unless they are experts in the murky corners of
> the language) would expect:
>
>   x=fn()
>
> when fn specifies a default argument of [], to be the same as writing:
>
>   x=fn([])
>
> and not be dependent on fn's entire call history.

Tell me, do you expect these to do the same thing?

x = []
fn(x)
fn(x)
fn(x)

# or

fn([])
fn([])
fn([])

The distinction is exactly the same. If you can understand that the
first one constructs a single object and uses it three times, then you
should be able to understand that the function default is also
constructed once and used every time.

> Your solution of using:
>
>   def fn(a=None):
>
> is not really satisfactory. Partly because it now utilities two mechanisms
> for the default: first to get None, then some extra code to get []. But also
> it's no longer obvious how the function works and what the default is. At
> least, you can't tell from a glance at the start of the function that [] is
> the default.

This I do agree with. It's a bit clunky. It would be nice to be able to say:

def fn(a=`[]`):
    """If a is not passed, it will be a new empty list"""

and have it function the same as:

def fn(*args):
    a = args[0] if args else []

but currently there's no mechanism for it. (The example spelling I
gave is almost certainly not going to be used, due to the Tim Peters'
Monitor Grit argument, but something could probably be found.) It's a
sufficiently common situation that it would merit its own syntax. Want
to write up a PEP? All you need is a syntax that people can get
behind.

ChrisA


From ben+python at benfinney.id.au  Wed Nov 18 21:08:45 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 19 Nov 2015 13:08:45 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <CAPTjJmp3N98ZmvSS-=NBzoQQOX5ojxG3GjkKrPB98_2-9nCv_A@mail.gmail.com>
Message-ID: <85k2ped9le.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> On Thu, Nov 19, 2015 at 12:41 PM, BartC <bc at freeuk.com> wrote:
> > On 18/11/2015 23:22, Chris Angelico wrote:
> >> On the contrary, it is certain always to be that exact object.
> >
> > But, not the same value that appears as the default?

It depends what you mean by ?the same value?.

> Nope. Mutable objects are never guaranteed to retain the same values.
> That's kinda the point.

Well, they are the *same value*, if by ?value? you mean ?a particular
object?.

On the other hand, the value can *change* over time, while remaining the
same object. So it will not be equal to its initial state, even though
it is the same object.

-- 
 \     ?[F]reedom of speech does not entail freedom to have your ideas |
  `\    accepted by governments and incorporated into law and policy.? |
_o__)                                   ?Russell Blackford, 2010-03-06 |
Ben Finney



From rosuav at gmail.com  Wed Nov 18 21:15:29 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 13:15:29 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <85k2ped9le.fsf@benfinney.id.au>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <CAPTjJmp3N98ZmvSS-=NBzoQQOX5ojxG3GjkKrPB98_2-9nCv_A@mail.gmail.com>
 <85k2ped9le.fsf@benfinney.id.au>
Message-ID: <CAPTjJmo5tT_9A1bfhwi5_VUwxuEk-rm+BZANZ2AnvjnXxG2OfA@mail.gmail.com>

On Thu, Nov 19, 2015 at 1:08 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
>> Nope. Mutable objects are never guaranteed to retain the same values.
>> That's kinda the point.
>
> Well, they are the *same value*, if by ?value? you mean ?a particular
> object?.
>
> On the other hand, the value can *change* over time, while remaining the
> same object. So it will not be equal to its initial state, even though
> it is the same object.

I would normally interpret "value" as "the quality compared with the
== operator". As such, mutables can change in value while retaining
their identities:

>>> x, y = [], []
>>> x == y
True
>>> x.append(1)
>>> x == y
False
>>> y.append(1)
>>> x == y
True

So a mutable default argument will always retain its identity (barring
shenanigans), but may not retain its value.

ChrisA


From vincent at vincentdavis.net  Wed Nov 18 21:22:30 2015
From: vincent at vincentdavis.net (Vincent Davis)
Date: Wed, 18 Nov 2015 19:22:30 -0700
Subject: Public key encryption example.
In-Reply-To: <CAPTjJmr8mmDU7xWgeMZUaxb8rHjYO=Vmk5_5_-9XynezpVM8Yg@mail.gmail.com>
References: <mailman.431.1447888735.16136.python-list@python.org>
 <87vb8ylv5a.fsf@nightsong.com>
 <CAPTjJmr8mmDU7xWgeMZUaxb8rHjYO=Vmk5_5_-9XynezpVM8Yg@mail.gmail.com>
Message-ID: <CALyJZZV79_sHb5ZZyUdEA_hvuy1f-zYb1Ps71-f4vvkofobDXA@mail.gmail.com>

Found an example, needs a little updating but then it works (appears to) in
python 3.5.
http://coding4streetcred.com/blog/post/Asymmetric-Encryption-Revisited-(in-PyCrypto)

Vincent Davis
720-301-3003

On Wed, Nov 18, 2015 at 5:04 PM, Chris Angelico <rosuav at gmail.com> wrote:

> On Thu, Nov 19, 2015 at 10:56 AM, Paul Rubin <no.email at nospam.invalid>
> wrote:
> > Vincent Davis <vincent at vincentdavis.net> writes:
> >> I am looking for the "simplest" example of sending(encrypting) and
> >> receiving(decrypting) using public key encryption. I am think of
> something
> >> along the lines of having all the keys in local files and saving and
> >> reading the message from a local file.
> >
> > It's very easy to make mistakes doing stuff like that.  Your simplest
> > bet is to shell out to GPG or something comparable.
>
> It's not that hard to pull up a library. I've never done it in Python,
> though.
>
> ChrisA
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From rxjwg98 at gmail.com  Wed Nov 18 21:55:33 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 18:55:33 -0800 (PST)
Subject: Question about 'print' in a loop
Message-ID: <75f51ee1-907c-47c4-9be9-58241ff83115@googlegroups.com>

Hi,

>From previous post, I get many helpful replies. Now I have a new question
when I run this example code:


---------
sq=[]
for xx in range(5):
    print 'here'
    sq.append(lambda:xx**2)
    
here
here
here
here
here

xx
Out[150]: 4

sq[2]()
Out[151]: 16

sq[3]()
Out[152]: 16
/////

There are only one time 5 'here' printed out, but there is no 'here' print
out in thereafter call sq[2]() etc. How to understand this phenomenon?

Thanks,



From rosuav at gmail.com  Wed Nov 18 22:11:02 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 14:11:02 +1100
Subject: Question about 'print' in a loop
In-Reply-To: <75f51ee1-907c-47c4-9be9-58241ff83115@googlegroups.com>
References: <75f51ee1-907c-47c4-9be9-58241ff83115@googlegroups.com>
Message-ID: <CAPTjJmrH=_UYssj0emM=Qy_2u5sN+3f0HKrkgV3Pj0bcsdAgEw@mail.gmail.com>

On Thu, Nov 19, 2015 at 1:55 PM, fl <rxjwg98 at gmail.com> wrote:
> There are only one time 5 'here' printed out, but there is no 'here' print
> out in thereafter call sq[2]() etc. How to understand this phenomenon?

Code does what code should.

Before you ask for comprehension of "this phenomenon", why don't you
tell us what you expect your code to do, and why? I just asked my
non-programmer sister and she was completely unsurprised by what
Python did here.

ChrisA


From rxjwg98 at gmail.com  Wed Nov 18 22:20:09 2015
From: rxjwg98 at gmail.com (fl)
Date: Wed, 18 Nov 2015 19:20:09 -0800 (PST)
Subject: Question about 'print' in a loop
In-Reply-To: <mailman.444.1447902665.16136.python-list@python.org>
References: <75f51ee1-907c-47c4-9be9-58241ff83115@googlegroups.com>
 <mailman.444.1447902665.16136.python-list@python.org>
Message-ID: <9982d291-891a-4132-a0cf-2bc94b50d05f@googlegroups.com>

On Wednesday, November 18, 2015 at 10:11:24 PM UTC-5, Chris Angelico wrote:
> On Thu, Nov 19, 2015 at 1:55 PM, fl  wrote:
> > There are only one time 5 'here' printed out, but there is no 'here' print
> > out in thereafter call sq[2]() etc. How to understand this phenomenon?
> 
> Code does what code should.
> 
> Before you ask for comprehension of "this phenomenon", why don't you
> tell us what you expect your code to do, and why? I just asked my
> non-programmer sister and she was completely unsurprised by what
> Python did here.
> 
> ChrisA

Excuse me. That is my unclear question.
I expect that each call sq will have one print 'here', as I suppose that
print 'here' is inside the loop.

Oh, I just realize that it is not a function. It constructs list sq.
When the loop (function as a constructor (not necessarily correct called),
it print 5 'here'.

Thanks for you feedback.


From auriocus at gmx.de  Thu Nov 19 02:04:08 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 19 Nov 2015 08:04:08 +0100
Subject: pyinstaller and Python 3.5 on Windows?
In-Reply-To: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2js4r$1kq$1@dont-email.me>

Am 18.11.15 um 23:46 schrieb Ulli Horlacher:
> To run my Python programs on other Windows systems without a Python
> installation I must create standalone Windows executables.
>
> pyinstaller runs without any problems with Python 2.7.10 on Windows 7, but
> with Python 3.5 I get:
>  [stack trace]

Are you using the newest version? According to 
http://www.pyinstaller.org/ they claim support for Python3. Does a hello 
world script work? If yes, it may have to do with some packages in your 
script. Is pywin32 a package that you load, or is it Pyinstaller that 
needs this?

	Christian



From dieter at handshake.de  Thu Nov 19 02:27:52 2015
From: dieter at handshake.de (dieter)
Date: Thu, 19 Nov 2015 08:27:52 +0100
Subject: Could you explain why the following generates 4 same elements
 list?
References: <3f1eecc8-e23d-4f86-abf8-38044939d085@googlegroups.com>
Message-ID: <87a8qala87.fsf@handshake.de>

fl <rxjwg98 at gmail.com> writes:

> Hi,
>
> I cannot reason out why the code:
> ////////
> def mpl():
>     return [lambda x : i * x for i in range(4)]
>     
> print [m(2) for m in mpl()]
> /////////
>
> has result:
>
> [6, 6, 6, 6]

The "i" in your lambda definition is a variable reference which
is not dereferenced (i.e. name replaced by the value) at definition
but only at call time. Thus, all your "lambda"s are in fact equal;
they all look up the current value of "i" when they are called
(which happens to be "3").

To avoid this, you must force the dereferencing at definition time.
This could look like:

     return [lambda x, i=i: i * x for i in range(4)]



From dieter at handshake.de  Thu Nov 19 02:31:04 2015
From: dieter at handshake.de (dieter)
Date: Thu, 19 Nov 2015 08:31:04 +0100
Subject: Question about 'print' in a loop
References: <75f51ee1-907c-47c4-9be9-58241ff83115@googlegroups.com>
Message-ID: <87610yla2v.fsf@handshake.de>

fl <rxjwg98 at gmail.com> writes:

> Hi,
>
> From previous post, I get many helpful replies. Now I have a new question
> when I run this example code:
>
>
> ---------
> sq=[]
> for xx in range(5):
>     print 'here'
>     sq.append(lambda:xx**2)
> ...
> sq[2]()
> Out[151]: 16
>
> sq[3]()
> Out[152]: 16
> /////

Same reason as in your previous thread: variables in (the body of) function
definitions (and "lambda"s, which are functions definitions, too) are
resolved/dereferenced at call time, not at function definition time.



From framstag at rus.uni-stuttgart.de  Thu Nov 19 02:50:21 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 19 Nov 2015 07:50:21 +0000 (UTC)
Subject: pyinstaller and Python 3.5 on Windows?
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
 <n2js4r$1kq$1@dont-email.me>
Message-ID: <n2juvt$14p$1@news2.informatik.uni-stuttgart.de>

Christian Gollwitzer <auriocus at gmx.de> wrote:
> Am 18.11.15 um 23:46 schrieb Ulli Horlacher:
> > To run my Python programs on other Windows systems without a Python
> > installation I must create standalone Windows executables.
> >
> > pyinstaller runs without any problems with Python 2.7.10 on Windows 7, but
> > with Python 3.5 I get:
> >  [stack trace]
> 
> Are you using the newest version?

Yes. Yesterday installed.


> According to http://www.pyinstaller.org/ they claim support for Python3.

Therefore my try :-)


> Does a hello world script work?

No. 
My test-program I tried to compile was:

#!/usr/bin/python

from tkinter import Tk,filedialog

askopenfilename = filedialog.askopenfilename

Tk().withdraw()
file = filedialog.askopenfilename()
print('File selected: "%s"\n' % file)


It runs directly, but I cannot compile it with pyinstaller.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From framstag at rus.uni-stuttgart.de  Thu Nov 19 02:54:28 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 19 Nov 2015 07:54:28 +0000 (UTC)
Subject: handling of non-ASCII filenames?
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
 <n2ibvh$5th$1@dont-email.me>
Message-ID: <n2jv7k$14p$2@news2.informatik.uni-stuttgart.de>

Christian Gollwitzer <auriocus at gmx.de> wrote:
> Am 18.11.15 um 17:45 schrieb Ulli Horlacher:
> > This is my encoding function:
> >
> > def url_encode(s):
> >    u = ''
> >    for c in list(s):
> >      if match(r'[_=:,;<>()+.\w\-]',c):
> >        u += c
> >      else:
> >        u += '%' + c.encode("hex").upper()
> >    return u
> >
> >
> 
> The quoting is applied to a UTF8 string.

encode("hex") works only with binary strings?
How do I convert a UTF8 string to binary?



> But I think you shouldn't do it yourself, use a library function:
> 
> import urllib
> urllib.quote(yourstring.encode('utf8'))

It does not encode exactly the same way I need it.
Besides this, I want to understand how Python handles strings and
character encoding. 


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From auriocus at gmx.de  Thu Nov 19 03:16:15 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Thu, 19 Nov 2015 09:16:15 +0100
Subject: handling of non-ASCII filenames?
In-Reply-To: <n2jv7k$14p$2@news2.informatik.uni-stuttgart.de>
References: <n2i9vt$icf$1@news2.informatik.uni-stuttgart.de>
 <n2ibvh$5th$1@dont-email.me> <n2jv7k$14p$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2k0c3$cjn$2@dont-email.me>

Am 19.11.15 um 08:54 schrieb Ulli Horlacher:
> Christian Gollwitzer <auriocus at gmx.de> wrote:
>> Am 18.11.15 um 17:45 schrieb Ulli Horlacher:
>>> This is my encoding function:
>>>
>>> def url_encode(s):
>>>     u = ''
>>>     for c in list(s):
>>>       if match(r'[_=:,;<>()+.\w\-]',c):
>>>         u += c
>>>       else:
>>>         u += '%' + c.encode("hex").upper()
>>>     return u
>>>
>>>
>>
>> The quoting is applied to a UTF8 string.
>
> encode("hex") works only with binary strings?
> How do I convert a UTF8 string to binary?

It's right in the other line I showed you:

Apfelkiste:Tests chris$ python
Python 2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
 >>> u"blabl?a".encode('utf8')
'blabl\xc3\xbca'
 >>>

	Christian


From c.buhtz at posteo.jp  Thu Nov 19 03:17:35 2015
From: c.buhtz at posteo.jp (c.buhtz at posteo.jp)
Date: Thu, 19 Nov 2015 09:17:35 +0100
Subject: PubMed / Entrez
Message-ID: <3p1Ylk6Wjgz5vMw@dovecot03.posteo.de>

I am looking for a way to use the PubMed (medical research search
engine) API (aka Entrez) with Python3.

Does anyone know packages for that?
-- 
GnuPGP-Key ID 0751A8EC


From motoom at xs4all.nl  Thu Nov 19 04:00:47 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Thu, 19 Nov 2015 10:00:47 +0100
Subject: how do I learn python ?
In-Reply-To: <BLU177-W25FC22D76121842F28AC97871C0@phx.gbl>
References: <BLU177-W25FC22D76121842F28AC97871C0@phx.gbl>
Message-ID: <CF2B7E9B-8ED0-4B79-9ABB-916B80D5FDB7@xs4all.nl>


> On 18 Nov 2015, at 05:58, ??? <hua_lin at live.cn> wrote:
> (nothing)

You might want to start at https://www.python.org/about/gettingstarted/

PS. Leaving the body of an email or usenet article empty is considered bad form.

Greetings,



From uganesh at qmschool.org.uk  Thu Nov 19 04:28:24 2015
From: uganesh at qmschool.org.uk (Uma Ganesh)
Date: Thu, 19 Nov 2015 09:28:24 +0000
Subject: Fwd: The results of your email commands
In-Reply-To: <564D944A.1070102@timgolden.me.uk>
References: <mailman.186.1447923771.16134.python-list@python.org>
 <CAHeQGp8R4s2miyq_1y3pnECMgLrHOwH=4uheec-t6oHP7mpqMw@mail.gmail.com>
 <564D944A.1070102@timgolden.me.uk>
Message-ID: <CAHeQGp93iUyEGo9Hz97JR4G+8brAkT2chXKuq=m6U3MJfFTB5w@mail.gmail.com>

> We are trying to use this for students GCSE & A'Level work and seem to
?
 be having this problem a lot.
> What is the cause and the solution to this.
>
>
> I need some help, everytime I install Python 3.3 on to a computer
?
overnight it changes to Python X. Therefore most of the files and
?
folders disappear please can you tell me why that is.
>
> ****************All jobs MUST be reported to the
helpdesk.******************
>
https://docs.google.com/a/qmschool.org.uk/forms/d/1fIRU9Xm-s36pAWtACiYanPyvYXvDb1sTSQl8LslVLDk/viewform
>
> Thank You
> Uma Ganesh
> Queensmead School
> Queens Walk
> South Ruislip
> Middlesex
> HA4 0LS
>
> On 19 November 2015 at 09:02, <python-list-owner at python.org
> <mailto:python-list-owner at python.org>> wrote:
>
>     The results of your email command are provided below. Attached is your
>     original message.
>
>     - Results:
>         Ignoring non-text/plain MIME parts
>         Invalid confirmation string.  Note that confirmation strings
expire
>     approximately 3 days after the initial request.  They also expire if
>     the request has already been handled in some way.  If your
>     confirmation has
>     expired, please try to re-submit your original request or message.
>
>     - Unprocessed:
>         Re: Your confirmation is required to join the Python-list
>     mailing list
>             confirm fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>         ****************All jobs MUST be reported to the
>     helpdesk.******************
>
>
https://docs.google.com/a/qmschool.org.uk/forms/d/1fIRU9Xm-s36pAWtACiYanPyvYXvDb1sTSQl8LslVLDk/viewform
>         Thank You
>         Uma Ganesh
>         Queensmead School
>         Queens Walk
>         South Ruislip
>         Middlesex
>         HA4 0LS
>         On 19 November 2015 at 09:01, <
>
>
python-list-confirm+fe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org
>     <mailto:
python-list-confirm%2Bfe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org>>
>         wrote:
>         > Mailing list subscription confirmation notice for mailing list
>         > Python-list
>         >
>         > We have received a request from 5.150.102.153 for subscription
>     of your
>         > email address, "uganesh at qmschool.org.uk
>     <mailto:uganesh at qmschool.org.uk>", to the
>         > python-list at python.org <mailto:python-list at python.org> mailing
>     list.  To confirm that you want to be
>         > added to this mailing list, simply reply to this message,
>     keeping the
>         > Subject: header intact.  Or visit this web page:
>
>     - Ignored:
>         >
>         >
>         >
>
https://mail.python.org/mailman/confirm/python-list/fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>         >
>         >
>         > Or include the following line -- and only the following line
>     -- in a
>         > message to python-list-request at python.org
>     <mailto:python-list-request at python.org>:
>         >
>         >     confirm fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>         >
>         > Note that simply sending a `reply' to this message should work
>     from
>         > most mail readers, since that usually leaves the Subject: line
>     in the
>         > right form (additional "Re:" text in the Subject: is okay).
>         >
>         > If you do not wish to be subscribed to this list, please simply
>         > disregard this message.  If you think you are being maliciously
>         > subscribed to the list, or have any other questions, send them
to
>         > python-list-owner at python.org
>     <mailto:python-list-owner at python.org>.
>         >
>
>     - Done.
>
>
>
>     ---------- Forwarded message ----------
>     From: Uma Ganesh <uganesh at qmschool.org.uk
>     <mailto:uganesh at qmschool.org.uk>>
>     To:
python-list-confirm+fe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org
>     <mailto:
python-list-confirm%2Bfe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org>
>     Cc:
>     Date: Thu, 19 Nov 2015 09:02:49 +0000
>     Subject: Re: Your confirmation is required to join the Python-list
>     mailing list
>
>         confirm fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>
>     ****************All jobs MUST be reported to the
>     helpdesk.******************
>
https://docs.google.com/a/qmschool.org.uk/forms/d/1fIRU9Xm-s36pAWtACiYanPyvYXvDb1sTSQl8LslVLDk/viewform
>
>     Thank You
>     Uma Ganesh
>     Queensmead School
>     Queens Walk
>     South Ruislip
>     Middlesex
>     HA4 0LS
>
>     On 19 November 2015 at 09:01,
>     <
python-list-confirm+fe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org
>     <mailto:
python-list-confirm+fe8b5eed3ddb48be4d09fb7c09630f21df6c9143 at python.org>>
>     wrote:
>
>         Mailing list subscription confirmation notice for mailing list
>         Python-list
>
>         We have received a request from 5.150.102.153 for subscription
>         of your
>         email address, "uganesh at qmschool.org.uk
>         <mailto:uganesh at qmschool.org.uk>", to the
>         python-list at python.org <mailto:python-list at python.org> mailing
>         list.  To confirm that you want to be
>         added to this mailing list, simply reply to this message,
>         keeping the
>         Subject: header intact.  Or visit this web page:
>
>
>
https://mail.python.org/mailman/confirm/python-list/fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>
>
>         Or include the following line -- and only the following line --
in a
>         message to python-list-request at python.org
>         <mailto:python-list-request at python.org>:
>
>             confirm fe8b5eed3ddb48be4d09fb7c09630f21df6c9143
>
>         Note that simply sending a `reply' to this message should work
from
>         most mail readers, since that usually leaves the Subject: line
>         in the
>         right form (additional "Re:" text in the Subject: is okay).
>
>         If you do not wish to be subscribed to this list, please simply
>         disregard this message.  If you think you are being maliciously
>         subscribed to the list, or have any other questions, send them to
>         python-list-owner at python.org <mailto:python-list-owner at python.org
>.
>
>
>
>


From rxjwg98 at gmail.com  Thu Nov 19 06:28:53 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 19 Nov 2015 03:28:53 -0800 (PST)
Subject: Is there an meaning of '[[]]' in a list?
Message-ID: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>

Hi,
In the previous exercises, I see list:
cc=[[],[],[]]

Then, I can have this:

ccc=[[[]],[[]],[[]]]

I can also have

ccc[0]
Out[158]: [[]]

ccc[0]='o'

ccc
Out[163]: ['o', [[]], [[]]]


I have question: Is there any difference between [[]] and []?
[[]] can have deeper assignment and use than 

ccc[0]='o'


Thanks,


From gandalf at shopzeus.com  Thu Nov 19 06:36:46 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Thu, 19 Nov 2015 12:36:46 +0100
Subject: Is there an meaning of '[[]]' in a list?
In-Reply-To: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
Message-ID: <564DB44E.8020503@shopzeus.com>


> I have question: Is there any difference between [[]] and []?
Yes.

[] - a list with zero elements. That is an empty list.
[[]] - A list with one element. (That element is an empty list.)

> [[]] can have deeper assignment and use than 
You can have it as deep as you want, if you have enough memory.



From steve at pearwood.info  Thu Nov 19 06:38:12 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 19 Nov 2015 22:38:12 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <CALwzidkbMJBw66toG+erAwWwGEp46rZ4TkZu58zw36XCQRfjsg@mail.gmail.com>
 <mailman.435.1447892092.16136.python-list@python.org>
 <03515f27-fb4c-49f0-9f02-2f5b5a8d16e5@googlegroups.com>
Message-ID: <564db4a5$0$1604$c3e8da3$5496439d@news.astraweb.com>

On Thu, 19 Nov 2015 11:34 am, fl wrote:

> This is my new
> question: What does 'del' do? It does not look like a thorough list
> deletion from the effect.

Of course not. Did you Read The Fine Manual? Or at least use the interactive
help function? At the Python prompt, enter:

help("del")

and you will see an explanation which includes this:

    Deletion of a name removes the binding of that name  from 
    the local or global namespace, depending on whether the 
    name occurs in a ``global`` statement in the same code 
    block.  If the name is unbound, a ``NameError`` exception 
    will be raised.


Let us try it with the interactive interpreter:

If the name "x" doesn't exist, and you try to delete it, you get an error:

py> del x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined

If "x" does exist, and you delete it, the name no longer exists:

py> x = 42
py> print(x)
42
py> del x
py> print(x)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined

So "del" deletes **names**. 

What happens after the name is deleted? Then the garbage collector may run,
and destroy the object that was bound to the name, reclaiming the memory
used. But **only** if the object is safe to destroy, otherwise that would
lead to segmentation faults and memory corruption.


Here we have ONE object with TWO names:

py> a = [1, 2, 3, 4]
py> b = a
py> b.append(999)
py> print(a)
[1, 2, 3, 4, 999]

If we delete one of those names, the other name keeps the list alive:


py> del a
py> print(b)
[1, 2, 3, 4, 999]





-- 
Steven



From __peter__ at web.de  Thu Nov 19 06:40:17 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 19 Nov 2015 12:40:17 +0100
Subject: Is there an meaning of '[[]]' in a list?
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
Message-ID: <n2kcf5$2st$1@ger.gmane.org>

fl wrote:

> Hi,
> In the previous exercises, I see list:
> cc=[[],[],[]]
> 
> Then, I can have this:
> 
> ccc=[[[]],[[]],[[]]]
> 
> I can also have
> 
> ccc[0]
> Out[158]: [[]]
> 
> ccc[0]='o'
> 
> ccc
> Out[163]: ['o', [[]], [[]]]
> 
> 
> I have question: Is there any difference between [[]] and []?
> [[]] can have deeper assignment and use than
> 
> ccc[0]='o'

I'm sure with a little effort and a few experiments on the commandline you 
can answer your question yourself. Please limit your posts to c.l.py to 
those questions that are a little harder.

Hint: when you experiment with nested lists use numbers, not strings as list 
entries that are not lists themselves. Strings can confuse you about the 
nesting level:

>>> items = ["foo"]
>>> items[0]
'foo'
>>> items[0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0]
'f'




From bc at freeuk.com  Thu Nov 19 06:41:43 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 11:41:43 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.440.1447898362.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
Message-ID: <n2kcdn$lq0$1@dont-email.me>

On 19/11/2015 01:59, Chris Angelico wrote:
> On Thu, Nov 19, 2015 at 12:41 PM, BartC <bc at freeuk.com> wrote:
>> On 18/11/2015 23:22, Chris Angelico wrote:
>>> On the contrary, it is certain always to be that exact object.
>>
>> But, not the same value that appears as the default?
>
> Nope. Mutable objects are never guaranteed to retain the same values.
> That's kinda the point.

But, presumably you would expect:

  a = []

to always assign an empty list to a? You don't expect this:

  a = []
  a.append(10)
  b = []

that b now has the same value of a, namely [10]. Fortunately this isn't 
the case.

>> Sorry, I didn't understand any of that.

> If you want to think of function defaults as being values, then yes.
> But they're not. They're objects.

That's not much help to someone who *does* want the default to supply 
the same missing value that they don't want to bother remembering and/or 
writing in the call.

Surely the language is trying to help people not hinder. How many times 
after all is this behaviour actually wanted? It's the equivalent of:

fndefault=[]

def fn(a=fndefault):
     a.append(10)
     return a

where it is known that a and fndefault share the same mutable data. 
(Although I bet some people are still surprised by that!)

>> I suspect those same people (unless they are experts in the murky corners of
>> the language) would expect:
....
>> and not be dependent on fn's entire call history.
>
> Tell me, do you expect these to do the same thing?
>
> x = []
> fn(x)
> fn(x)
> fn(x)
>
> # or
>
> fn([])
> fn([])
> fn([])

No I don't. But I expect the version with the default argument to be 
exactly the same as the last lot of calls, namely for:

fn()
fn()
fn()

to be equivalent to:

temp=[]
fn(temp)
temp=[]
fn(temp)
temp=[]
fn(temp)

> The distinction is exactly the same. If you can understand that the
> first one constructs a single object and uses it three times, then you
> should be able to understand that the function default is also
> constructed once and used every time.

As I said, it's bizarre. It means that for certain types, Python doesn't 
have a default that works per call, but only a default that works once 
per program.

-- 
Bartc


From kw at codebykevin.com  Thu Nov 19 06:41:52 2015
From: kw at codebykevin.com (Kevin Walzer)
Date: Thu, 19 Nov 2015 06:41:52 -0500
Subject: pyinstaller and Python 3.5 on Windows?
In-Reply-To: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
Message-ID: <n2kcdk$l39$1@dont-email.me>

On 11/18/15 5:46 PM, Ulli Horlacher wrote:
>
> ImportError: DLL load failed: The specified module could not be found.
>
>
> Is there a solution available?
>

I understand that Python 3.5 has shipped how the MS dll's from Visual 
Studio are shipped, and perhaps the freezing tools (pyinstaller, py2exe) 
haven't yet caught up. Consider filing a bug with the pyinstaller 
developers.

--Kevin

-- 
Kevin Walzer
Code by Kevin/Mobile Code by Kevin
http://www.codebykevin.com
http://www.wtmobilesoftware.com


From hayesstw at telkomsa.net  Thu Nov 19 06:47:05 2015
From: hayesstw at telkomsa.net (Steve Hayes)
Date: Thu, 19 Nov 2015 13:47:05 +0200
Subject: how do I learn python ?
References: <mailman.450.1447923413.16136.python-list@python.org>
Message-ID: <6ldr4b9c146bo8tgl9fdbrfqbr2b7apflq@4ax.com>

On Wed, 18 Nov 2015 04:58:30 +0000, ?????? <hua_lin at live.cn> wrote:

> 		 	   		  


-- 
Steve Hayes from Tshwane, South Africa
Web:  http://www.khanya.org.za/stevesig.htm
Blog: http://khanya.wordpress.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk


From lac at openend.se  Thu Nov 19 06:51:23 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 19 Nov 2015 12:51:23 +0100
Subject: Public key encryption example.
In-Reply-To: <CALyJZZUEV311wZ5+QGkmfW3o=FsjDBAekAXW1FZ13LeeLtHK_A@mail.gmail.com>
References: <CALyJZZUEV311wZ5+QGkmfW3o=FsjDBAekAXW1FZ13LeeLtHK_A@mail.gmail.com>
Message-ID: <201511191151.tAJBpN9j018075@fido.openend.se>

In a message of Wed, 18 Nov 2015 16:18:28 -0700, Vincent Davis writes:
>This might be a "Let me Google that for you question", I tried.
>I am looking for the "simplest" example of sending(encrypting) and
>receiving(decrypting) using public key encryption. I am think of something
>along the lines of having all the keys in local files and saving and
>reading the message from a local file.
>
>Possibly using cryptography library elliptic-curve
>https://cryptography.io/en/latest/hazmat/primitives/asymmetric/ec/#elliptic-curve-signature-algorithms
>
>Surly there is an example out there?
>
>Vincent Davis

pycrypto does this.

https://pypi.python.org/pypi/pycrypto
code and diagrams here
http://www.laurentluce.com/posts/python-and-cryptography-with-pycrypto/

There really isn't much to it.

Laura


From rosuav at gmail.com  Thu Nov 19 06:58:33 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 19 Nov 2015 22:58:33 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2kcdn$lq0$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
 <n2kcdn$lq0$1@dont-email.me>
Message-ID: <CAPTjJmp61oUgp8fO9dS0vUGvLf_iCSK8xcumsW1P=QbJ8kXnvA@mail.gmail.com>

On Thu, Nov 19, 2015 at 10:41 PM, BartC <bc at freeuk.com> wrote:
> As I said, it's bizarre. It means that for certain types, Python doesn't
> have a default that works per call, but only a default that works once per
> program.

No, it's not "for certain types". Regardless of the type, the
expression that defines the default is evaluated at *function
definition*, not at each *function call*. (That's not the same as
"once per program", although for 99% of situations, it'll be
indistinguishable.)

ChrisA


From gengyangcai at gmail.com  Thu Nov 19 06:59:53 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Thu, 19 Nov 2015 03:59:53 -0800 (PST)
Subject: Writing a Financial Services App in Python
Message-ID: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>


>From YCombinator's new RFS, This is the problem I want to solve as it is a severe problem I face myself and something I need. I want to write this app in Python as I heard that Python is a great language that many programmers use ... How / where do I start ? The problem is detailed below :

FINANCIAL SERVICES

Saving money is hard and Americans are particularly bad at it. Because the personal savings rate has largely been falling since the early 80s, we don't have sufficient cushions to face economic shocks, weather unexpected unemployment, or even enjoy our retirements.
Its simply too hard to find good ways to save or to invest. Savings accounts only pay a fraction of what's needed to keep up with inflation. Picking individual stocks and bonds exposes investors to huge volatility and does nothing to guarantee a return.

While investors can dampen their volatility through various exchanges or closed ended funds, the reality is that few have the expertise needed to properly mix those funds, rebalance them, and optimize them for taxes to capture the best possible return (no matter how you define that) given each dollar of invested capital. Even if investors were able to pick optimal investment strategies, they'd find that that fees are a huge drag on performance.

This seems to us like something software should help solve. We'd like to see teams tackling each of the component issues around saving and investing, along with ones tackling the entire package.


Thanks alot !

Cai Gengyang


From lac at openend.se  Thu Nov 19 07:09:29 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 19 Nov 2015 13:09:29 +0100
Subject: PubMed / Entrez
In-Reply-To: <3p1Ylk6Wjgz5vMw@dovecot03.posteo.de>
References: <3p1Ylk6Wjgz5vMw@dovecot03.posteo.de>
Message-ID: <201511191209.tAJC9TvR019795@fido.openend.se>

In a message of Thu, 19 Nov 2015 09:17:35 +0100, c.buhtz at posteo.jp writes:
>I am looking for a way to use the PubMed (medical research search
>engine) API (aka Entrez) with Python3.
>
>Does anyone know packages for that?

https://pypi.python.org/pypi/Bio_Eutils/1.63

Or just get BioPython and use the Entrez from that.

Laura


From steve at pearwood.info  Thu Nov 19 07:19:53 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 19 Nov 2015 23:19:53 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
Message-ID: <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>

On Thu, 19 Nov 2015 10:14 am, BartC wrote:

> On 18/11/2015 22:11, Ian Kelly wrote:

>> The list0 parameter has a default value, which is [], an initially
>> empty list. The default value is evaluated when the function is
>> defined, not when it is called, so the same list object is used each
>> time and changes to the list are consequently retained between calls.
> 
> That is really bizarre behaviour.

It is standard early binding behaviour, applied to function defaults.

Early versus late binding crops up in many places when programming:

https://support.microsoft.com/en-us/kb/245115

http://javascript.info/tutorial/binding

https://msdn.microsoft.com/en-us/library/0tcf61s1.aspx

Unfortunately, like many evocative or useful terms in computing, it the term
isn't used consistently. There are at least two related, but distinct, uses
for "early/late binding", and Wikipedia only talks about the *other* one:

https://en.wikipedia.org/wiki/Late_binding

In Python terms, *all* (or nearly all?) name binding (assignment) is
equivalent to C++ late binding, a.k.a. "dynamic dispatch". But Python also
uses early/late binding to refer to when the default object is assigned.

Consider this pair of functions:


def expensive():
    # Simulate some expensive calculation or procedure.
    time.sleep(100)
    return random.randint(1, 6)


def demo(arg=expensive()):
    return arg + 1


Now we call the second function four times, without an argument so that the
default value is used:

demo()
demo()
demo()
demo()

What results do you expect?

There are two standard behaviours:

Early binding means that the default value is generated *once*, when the
function `demo` is created. That's expensive, but it only gets used once,
and the default value is now fixed, and can be retrieved almost instantly
in subsequent calls. That's what Python uses.

Late binding means that the default value is generated every time you call
the function. That's expensive, and confusing. Why is the function
parameter list being re-evaluated each time the function is called? Why is
the default value different each time I call the function? Now *that's*
bizarre.

Compared to the weirdness of late binding, Python's early binding makes much
more sense.

Another advantage of early binding is that it involves a consistent
execution model: only the function body is executed when you call the
function, not the function declaration and parameter list.

def demo(arg=expensive()):  # declaration, including the parameter list
    # function body is indented


Now it is easy to tell which part gets executed when: just look at the
indentation.

Both early and late binding are useful, so which should a language default
to? (Assuming it doesn't offer both.) I think that there is absolutely no
doubt that function defaults should use early binding. The overwhelming
advantage of early binding is this:

- if the language defaults to early binding, it is *easy* for the 
  programmer to get late binding semantics;

- if the language defaults to late binding, it is *very difficult*
  for the programmer to get early binding semantics.


Given early binding, like Python has, it is easy to get late binding
semantics. All you have to do is use a sentinel value, and move the code
you want to execute every time the function is called into the body of the
function. The most common sentinel is None:

def demo(arg=None):
    if arg is None:
        arg = expensive()
    ...


Now it is obvious that expensive() will be called each time you call demo()
(with no argument provided), since the call to expensive is inside the
function body.

But let's try going the other way. Suppose function defaults were evaluated
each and every time you called the function. How could you *avoid* the
expense and waste of re-evaluating the default over and over again?

You can't, or at least, not cleanly and easily. The most obvious way is to
use a global variable:

ARG = expensive()

def demo(arg=ARG):
    ...


This is ... horrible. You are still evaluating the default each time, but at
least it is only a global variable lookup, not an expensive function call.
But the cost is great. Now you have to pollute the module with a global
variable for every function that has a default value. This breaks
encapsulation -- the default value for the function is no longer visible in
the function's declaration, you have to hunt for it through your module.
And what if somebody changes the global, or deletes it?



> So, looking at some source code, a default value for certain types is
> only certain to be that value for the very first call of that function?

When you deal with mutable objects, you have to expect them to mutate. The
whole point of mutability is that their value can change.

If you use a mutable default object, it is still mutable, and can change its
value. If you don't want that, then use an immutable object.


>  > The default value is evaluated when the function is
>  > defined, not when it is called
> 
> Given the amount of pointless dynamic stuff that goes on in Python, I'm
> surprised they've overlooked this one!
> 
> It seems simple enough to me to check for a missing parameter, and to
> assign whatever default value was designated ([] in this case). (How
> does the default mechanism work now?)

What "seems" simple is not simple. The function default is not guaranteed to
be a simple literal. Defaults are arbitrarily complex expressions:

def func(a, b=[1, x] + [random.random() for i in range(x**4)]): ...


So you have to store that expression:

    [1, x] + [random.random() for i in range(x**4)]

together with enough information to know which scope it will be evaluated
in. And you have to decide: should that be a closure, or a regular function
call? Whichever decision you make, you will make some people unhappy.

There are consequences of your choice:

- Assuming that "x" is a global variable, then making the expression a
closure will mean that the value of x is kept alive, possibly long after
the default value is no longer needed.

- But if you make the expression a non-closure, then the caller is
responsible for ensuring that x is not deleted. If it is deleted, then you
will get a NameError trying to evaluate the default value.

Whichever option you choose, there will be a multitude of people on the
internet telling you that you got it wrong.


-- 
Steven



From framstag at rus.uni-stuttgart.de  Thu Nov 19 07:25:39 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 19 Nov 2015 12:25:39 +0000 (UTC)
Subject: pyinstaller and Python 3.5 on Windows?
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
 <n2kcdk$l39$1@dont-email.me>
Message-ID: <n2kf43$4u7$1@news2.informatik.uni-stuttgart.de>

Kevin Walzer <kw at codebykevin.com> wrote:

> I understand that Python 3.5 has shipped how the MS dll's from Visual 
> Studio are shipped, and perhaps the freezing tools (pyinstaller, py2exe) 
> haven't yet caught up. Consider filing a bug with the pyinstaller 
> developers.

http://pythonhosted.org/PyInstaller/#windows

  Installing in Windows

  For Windows, PyWin32 or the more recent pypiwin32, is a prerequisite.
  The latter is installed automatically when you install PyInstaller using
  pip or easy_install. If necessary, follow the pypiwin32 link to install
  it manually.

I have installed PyInstaller using "pip install pyinstaller".

Ok, then:

C:\Users\admin>pip install pywin32
Collecting pywin32
  Could not find a version that satisfies the requirement pywin32 (from versions: )
  Some externally hosted files were ignored as access to them may be unreliable
(use --allow-external pywin32 to allow).
No matching distribution found for pywin32


C:\Users\admin>pip install pypiwin32
Collecting pypiwin32
  Downloading pypiwin32-219-cp35-none-win32.whl (7.9MB)
    100% |################################| 7.9MB 61kB/s
Installing collected packages: pypiwin32
Exception:
Traceback (most recent call last):
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\basecommand.py",
 line 211, in main
    status = self.run(options, args)
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\commands\install
.py", line 311, in run
    root=options.root_path,
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\req\req_set.py",
 line 646, in install
    **kwargs
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\req\req_install.
py", line 803, in install
    self.move_wheel_files(self.source_dir, root=root)
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\req\req_install.
py", line 998, in move_wheel_files
    isolated=self.isolated,
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\wheel.py", line
339, in move_wheel_files
    clobber(source, lib_dir, True)
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\wheel.py", line
317, in clobber
    shutil.copyfile(srcfile, destfile)
  File "c:\program files (x86)\python 3.5\lib\shutil.py", line 115, in copyfile
    with open(dst, 'wb') as fdst:
PermissionError: [Errno 13] Permission denied: 'c:\\program files (x86)\\python
3.5\\Lib\\site-packages\\PyWin32.chm'


Why "Permission denied"? I am logged in as administrator! Stupid Windows...


Then https://pypi.python.org/pypi/pypiwin32/219 :

pypiwin32-219-cp35-none-win32.whl  Python Wheel    cp35     2015-01-09 7MB

"Python Wheel"?!

http://python-packaging-user-guide.readthedocs.org/en/latest/installing/#install-pip-setuptools-and-wheel

C:\Users\admin>pip install wheel
Collecting wheel
  Downloading wheel-0.26.0-py2.py3-none-any.whl (63kB)
    100% |################################| 65kB 1.3MB/s
Installing collected packages: wheel
  Failed to write executable - trying to use .deleteme logic
Exception:
Traceback (most recent call last):
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\_vendor\distlib\
scripts.py", line 209, in _write_script
    self._fileop.write_binary_file(outname, script_bytes)
  File "c:\program files (x86)\python 3.5\lib\site-packages\pip\_vendor\distlib\
util.py", line 388, in write_binary_file
    with open(path, 'wb') as f:
PermissionError: [Errno 13] Permission denied: 'c:\\program files (x86)\\python
3.5\\Scripts\\wheel.exe'


Looks like I have a broken Windows :-(

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From steve at pearwood.info  Thu Nov 19 07:45:41 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 19 Nov 2015 23:45:41 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
 <n2kcdn$lq0$1@dont-email.me>
Message-ID: <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>

On Thu, 19 Nov 2015 10:41 pm, BartC wrote:


> I expect the version with the default argument to be
> exactly the same as the last lot of calls, namely for:
> 
> fn()
> fn()
> fn()
> 
> to be equivalent to:
> 
> temp=[]
> fn(temp)
> temp=[]
> fn(temp)
> temp=[]
> fn(temp)

Why on earth would you expect that?

I don't mean that it isn't sometimes useful. Of course it is sometimes
useful, there's no doubt about that. But why would you expect the language
to default to the *slow*, *expensive*, *complicated* behaviour instead of
the *fast*, *cheap*, *simple* behaviour?

You already have one way to set the argument to a fresh list every time you
call the function: put the code you want executed inside the body of the
function. There's no need for a *second* way to get the same result.

But if you want the default value to be evaluated exactly once, and once
only, there is no real alternative to early binding. You could use a global
variable, of course, but that is no solution -- that's a problem waiting to
happen.

To get late binding, the interpreter needs to record the default expression
*and its scope* in some sort of executable code. The traditional name for
that is stolen from Algol, "thunk". And you need to decide whether it will
behave like a closure or not.

It needs to work sensibly with code like this:


i = j = k = -1
def demo():
    array = []
    for i in range(5):
        def factory():
            j = i
            def f(x=i + i**2, y=3*j+1, z=k**2 - k):
                return ((x, y, z), (i, j, k))
            return f
        array.append(factory())
    return array

func = demo()[1]
i = j = k = 9999
print(func())


>> The distinction is exactly the same. If you can understand that the
>> first one constructs a single object and uses it three times, then you
>> should be able to understand that the function default is also
>> constructed once and used every time.
> 
> As I said, it's bizarre. It means that for certain types, Python doesn't
> have a default that works per call, but only a default that works once
> per program.

Nonsense. The semantics of default values is *completely* independent of the
type. Python ALWAYS uses early binding, regardless of the type. Whether the
default is an int, None, a list, a dict, a float, or some other instance,
the behaviour is the same: the default value is the specific instance which
the default expression evaluates to when the function is created.


-- 
Steven



From bc at freeuk.com  Thu Nov 19 08:19:25 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 13:19:25 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2ki4t$aqj$1@dont-email.me>

On 19/11/2015 12:19, Steven D'Aprano wrote:
> On Thu, 19 Nov 2015 10:14 am, BartC wrote:

> Consider this pair of functions:
>
>
> def expensive():
>      # Simulate some expensive calculation or procedure.
>      time.sleep(100)
>      return random.randint(1, 6)
>
>
> def demo(arg=expensive()):
>      return arg + 1
>
>
> Now we call the second function four times, without an argument so that the
> default value is used:
>
> demo()
> demo()
> demo()
> demo()
>
> What results do you expect?

If someone /wants/ expensive() to be called each time, then why not? If 
they don't, then it seems easy enough to write:

demo_default=expensive()
def demo(arg=demo_default):
	...

(As you mention later...)

> - if the language defaults to early binding, it is *easy* for the
>    programmer to get late binding semantics;
>
> - if the language defaults to late binding, it is *very difficult*
>    for the programmer to get early binding semantics.

I got the impression that Python was a nice, easy language for everyone 
to use. Not one where you need a Master's degree in CS to understand the 
nuances of! And to understand why something that is so blindingly 
obvious doesn't work.

> But let's try going the other way. Suppose function defaults were evaluated
> each and every time you called the function. How could you *avoid* the
> expense and waste of re-evaluating the default over and over again?

I use default parameters a lot in other languages.

99% of the time the default value is a constant. And most often that 
constant is 0, "" or an empty list.

You want these very common examples to /just work/ instead of going to 
lengths trying to explain why they don't.

> You can't, or at least, not cleanly and easily. The most obvious way is to
> use a global variable:
>
> ARG = expensive()
>
> def demo(arg=ARG):
>      ...
>
> This is ... horrible. You are still evaluating the default each time,

I implement an interpreted language where these calls:

   demo()
   demo(ARG)

would have exactly the same cost.

I understand that Python is very different: at the call-site, the 
compiler has no idea of the number of arguments a function defines or 
what the default values might be, or even if it is a function that is 
being called.

But even under those circumstances, I would endeavour to make such a 
function call as fast as is practical.

(That could involve a runtime check on number of parameters, 
substituting the equivalent of None for missing ones, or whatever 
default expression has been declared.

But here, I am benefiting from my language not being Python which does 
seem to like making things difficult.)

> but at
> least it is only a global variable lookup,

Maybe you can wrap the entire module inside a function? Other than a bit 
at the end that calls that function. Does that solve the global lookup 
problem?

> When you deal with mutable objects, you have to expect them to mutate. The
> whole point of mutability is that their value can change.

That [] doesn't look like an object that could change. It looks like an 
empty list constructor. You would expect a constructor for an empty list 
to yield an empty list throughout a program! (As it does, in most other 
contexts.)

You presumably think differently because you have some inside knowledge 
of how Python works, and know that that [] undergoes a one-time 
assignment to a local, persistent 'default' variable where it's value 
can indeed by changed. (Thanks to another Python feature where an 
assignment is a very shallow copy of an object.) And it is that volatile 
variable that is the actual default.

But not everyone is going to know that.

-- 
Bartc


From framstag at rus.uni-stuttgart.de  Thu Nov 19 08:32:24 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 19 Nov 2015 13:32:24 +0000 (UTC)
Subject: pyinstaller and Python 3.5 on Windows?
References: <n2iv3p$o1n$2@news2.informatik.uni-stuttgart.de>
 <n2kcdk$l39$1@dont-email.me> <n2kf43$4u7$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n2kj18$69s$1@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:

> C:\Users\admin>pip install pypiwin32
> Collecting pypiwin32
>   Downloading pypiwin32-219-cp35-none-win32.whl (7.9MB)
>     100% |################################| 7.9MB 61kB/s
> Installing collected packages: pypiwin32
> Exception:
(...)
> PermissionError: [Errno 13] Permission denied: 'c:\\program files (x86)\\python
> 3.5\\Lib\\site-packages\\PyWin32.chm'
> 
> 
> Why "Permission denied"? I am logged in as administrator! Stupid Windows...

I found, I have to deactivate Windows UAC with 
C:\Windows\System32\UserAccountControlSettings.exe

Then I was able to run

pip install pypiwin32
pip install pyinstaller

without errors.

BUT pyinstaller does not work:

S:\python>pyinstaller.exe --onefile tk.py
failed to create process.

S:\python>pyinstaller --version
failed to create process.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rosuav at gmail.com  Thu Nov 19 08:45:19 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 00:45:19 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2ki4t$aqj$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
Message-ID: <CAPTjJmoZQKbMb73voizMeid60pn5EfHVwyA00RnYLMKhpJSoxw@mail.gmail.com>

On Fri, Nov 20, 2015 at 12:19 AM, BartC <bc at freeuk.com> wrote:
> You presumably think differently because you have some inside knowledge of
> how Python works, and know that that [] undergoes a one-time assignment to a
> local, persistent 'default' variable where it's value can indeed by changed.
> (Thanks to another Python feature where an assignment is a very shallow copy
> of an object.) And it is that volatile variable that is the actual default.
>
> But not everyone is going to know that.

Correct: We think certain things because we understand how Python
behaves. You, too, can join the Inner Circle of Pythonistas; all you
have to do is read this (and/or watch the video):

http://nedbatchelder.com/text/names1.html

ChrisA


From mal at europython.eu  Thu Nov 19 09:31:17 2015
From: mal at europython.eu (M.-A. Lemburg)
Date: Thu, 19 Nov 2015 15:31:17 +0100
Subject: EuroPython 2016: Kick-off
Message-ID: <564DDD35.7020106@europython.eu>

The EuroPython 2016 Team is ready for starting the organization of
next year?s event:


                *** http://ep2016.europython.eu/ ***

                         July 17 - 24 2016


If you would like to actively help with the organization, we?d love to
have you as volunteer in one of our workgroups. Please see the
EuroPython Workgroups page for how to sign up.

On-site Team WG
----------------

One of the workgroups, the on-site team workgroup, is especially
important, since they provide the services and management on-site in
Bilbao, as well as in the case of EuroPython 2016, also take on a
major role in the financial and legal infrastructure of the conference
organization.

This team is your contact in case you have questions related to
on-site setups.

 * Oier Echaniz Beneitez (Chair)
 * Borja Ayerdi Vilches
 * Darya Chyzhyk
 * Ion Marqu?s
 * Jos? David Nu?ez
 * Alexandre Savio
 * Luis Javier Salvatierra

Conference Administration WG
----------------------------

Manages and organizes the administration side of the conference, in
particular: contracts, venue contact, ticket support, satellite
conferences, legal support, insurance, licensing.

 * Marc-Andre Lemburg (Chair)
 * Borja Ayerdi Vilches
 * Vicky Twomey-Lee
 * St?phane Wirtel

Finance WG
----------

Manages and organizes the finances and budget of the conference, in
particular: budget, controlling, accounting, billing, invoicing,
taxes, payment system administration.

 * Borja Ayerdi Vilches (Chair)
 * Darya Chyzhyk
 * Marc-Andre Lemburg
 * Anthon van der Neut (EPS Treasurer)
 * St?phane Wirtel

Sponsors WG
-----------

Manages and organizes the sponsor activities of the conference, in
particular: sponsor contacts, sponsor logistics, room/booth
assignment, recruiting session, jobs fair, exhibit hall, startup row.

 * Fabio Pilger (Chair)
 * Borja Ayerdi Vilches
 * Darya Chyzhyk
 * Ra?l Cumplido
 * Marc-Andre Lemburg
 * Alexandre Savio
 * Vicky Twomey-Lee

Communications WG
-----------------

Manages and organizes the public communication and community relations
of the conference, in particular: press, community relations,
diversity/outreach/CoC, CoC contact, announcements, social media,
attendee tools, volunteer coordination, mailing lists, Trello and
Loomio groups.

 * Marc-Andre Lemburg (Chair)
 * Darya Chyzhyk
 * Ra?l Cumplido
 * Kerstin Kollmann
 * Leire Ozaeta
 * Vicky Twomey-Lee
 * Chris Ward
 * St?phane Wirtel

Support WG
----------

Manages and organizes the attendee/speaker support of the conference,
in particular: helpdesk, attendee support contact, visa help, travel
management.

 * Christian Barra
 * Aisha Bello
 * Darya Chyzhyk
 * Anthon van der Neut
 * Alexandre Savio
 * St?phane Wirtel

Financial Aid WG
----------------

Manages and organizes the financial aid program of the conference, in
particular: setup, grant selection, aid organisation.

 * Darya Chyzhyk
 * Vicky Twomey-Lee
 * St?phane Wirtel

Marketing/Design WG
-------------------

Create and manage marketing and design aspects of the conference, in
particular: brochures, advertisements, banners, flyers, travel guide,
t-shirts, lanyards, badges, panels, logo.

 * Darya Chyzhyk
 * Marc-Andre Lemburg
 * Alexandre Savio
 * St?phane Wirtel

Program WG
----------

Manages and organizes the conference program of the conference, in
particular: talk selection/voting, scheduling, session chairs,
sprint/openspace/keynote/lightning talks/poster session organization.

 * Alexandre Savio (Chair)
 * Alexander Hendorf  (Co-chair)
 * Christian Barra
 * Ra?l Cumplido
 * Moshe Goldstein
 * Vicky Twomey-Lee
 * Chris Ward

Web WG
------

Manages and organizes the web site, in particular: web site support,
helpdesk ticket system, administration, backups, payment system
integration, hosting.

 * Christian Barra (Chair)
 * Oier Beneitez
 * Ra?l Cumplido
 * Cesar Desales
 * Patrick Guido
 * Marc-Andre Lemburg
 * Fabio Pliger
 * Alexandre Savio
 * St?phane Wirtel

Media WG
--------

Manage and organize the talk and session recordings of the conference,
in particular: video recording, live streaming, uploads to YouTube and
archive.org.

 * Anthon van der Neut (Chair)
 * Luis Javier Salvatierra

Code of Conduct WG
------------------

Manage and organize the code of conduct (CoC) workflows, create CoC
documents, provide CoC contacts and handle CoC requests.

 * Darya Chyzhyk
 * Marc-Andre Lemburg
 * Anthon van der Neut
 * Leire Ozaeta

On-Site Volunteers
------------------

In addition to several of the EuroPython Workgroup members, we will
need quite a few attendees helping us as session manager, room
manager, at the registration desk, bag stuffing and during set up and
tear down of the conference.

We will run a separate announcement for on-site volunteers closer to
the event.


Enjoy,
--
EuroPython Society
http://www.europython-society.org/


From jrmy.lnrd at gmail.com  Thu Nov 19 10:02:27 2015
From: jrmy.lnrd at gmail.com (Jeremy Leonard)
Date: Thu, 19 Nov 2015 07:02:27 -0800 (PST)
Subject: Writing a Financial Services App in Python
In-Reply-To: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
Message-ID: <529622b6-3649-419d-a303-03e48d90c294@googlegroups.com>

On Thursday, November 19, 2015 at 7:00:05 AM UTC-5, Cai Gengyang wrote:
> From YCombinator's new RFS, This is the problem I want to solve as it is a severe problem I face myself and something I need. I want to write this app in Python as I heard that Python is a great language that many programmers use ... How / where do I start ? The problem is detailed below :
> 
> FINANCIAL SERVICES
> 
> Saving money is hard and Americans are particularly bad at it. Because the personal savings rate has largely been falling since the early 80s, we don't have sufficient cushions to face economic shocks, weather unexpected unemployment, or even enjoy our retirements.
> Its simply too hard to find good ways to save or to invest. Savings accounts only pay a fraction of what's needed to keep up with inflation. Picking individual stocks and bonds exposes investors to huge volatility and does nothing to guarantee a return.
> 
> While investors can dampen their volatility through various exchanges or closed ended funds, the reality is that few have the expertise needed to properly mix those funds, rebalance them, and optimize them for taxes to capture the best possible return (no matter how you define that) given each dollar of invested capital. Even if investors were able to pick optimal investment strategies, they'd find that that fees are a huge drag on performance.
> 
> This seems to us like something software should help solve. We'd like to see teams tackling each of the component issues around saving and investing, along with ones tackling the entire package.
> 
> 
> Thanks alot !
> 
> Cai Gengyang

What platform do you want the app to target (web/desktop/etc...)?

Jeremy


From gengyangcai at gmail.com  Thu Nov 19 10:24:54 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Thu, 19 Nov 2015 07:24:54 -0800 (PST)
Subject: Writing a Financial Services App in Python
In-Reply-To: <529622b6-3649-419d-a303-03e48d90c294@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
 <529622b6-3649-419d-a303-03e48d90c294@googlegroups.com>
Message-ID: <b9f3883d-5e16-441d-9f57-79826cdc1d23@googlegroups.com>

It will be a web-based application. 

Something like this : https://www.slicedinvesting.com/, but with different, better, more features and also graphics , forums, a system to track your daily, monthly expenses and earnings, a graphical tutorial system to teach users financial literacy , learn and utilise ways to invest and trade their money properly and create computerised trend following systems to trade stocks in the stock market. 

The truth is, very few individual investors really know how to properly trade stocks , and hedge funds are open to mainly very wealthy clients. Computerised and automated trend following systems can legally create huge profits for investors if a disciplined automated systems are utilised. 

I for example, am a terrible trader because of having almost zero discipline and thus keep losing money. My plan is to create such an all-in-one platform to help individual users like myself who might not have millions of dollars to invest in professional hedge funds properly invest , trade , keep track of their money and also network with our individual investors. 



On Thursday, November 19, 2015 at 11:03:50 PM UTC+8, Jeremy Leonard wrote:
> On Thursday, November 19, 2015 at 7:00:05 AM UTC-5, Cai Gengyang wrote:
> > From YCombinator's new RFS, This is the problem I want to solve as it is a severe problem I face myself and something I need. I want to write this app in Python as I heard that Python is a great language that many programmers use ... How / where do I start ? The problem is detailed below :
> > 
> > FINANCIAL SERVICES
> > 
> > Saving money is hard and Americans are particularly bad at it. Because the personal savings rate has largely been falling since the early 80s, we don't have sufficient cushions to face economic shocks, weather unexpected unemployment, or even enjoy our retirements.
> > Its simply too hard to find good ways to save or to invest. Savings accounts only pay a fraction of what's needed to keep up with inflation. Picking individual stocks and bonds exposes investors to huge volatility and does nothing to guarantee a return.
> > 
> > While investors can dampen their volatility through various exchanges or closed ended funds, the reality is that few have the expertise needed to properly mix those funds, rebalance them, and optimize them for taxes to capture the best possible return (no matter how you define that) given each dollar of invested capital. Even if investors were able to pick optimal investment strategies, they'd find that that fees are a huge drag on performance.
> > 
> > This seems to us like something software should help solve. We'd like to see teams tackling each of the component issues around saving and investing, along with ones tackling the entire package.
> > 
> > 
> > Thanks alot !
> > 
> > Cai Gengyang
> 
> What platform do you want the app to target (web/desktop/etc...)?
> 
> Jeremy


From ian.g.kelly at gmail.com  Thu Nov 19 10:42:00 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 08:42:00 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
 <n2kcdn$lq0$1@dont-email.me>
 <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzidnkAR6AcHQP8rKivoMoKk7Vgahw+nhhnz1WhFwgwxw52w@mail.gmail.com>

On Thu, Nov 19, 2015 at 5:45 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> But if you want the default value to be evaluated exactly once, and once
> only, there is no real alternative to early binding. You could use a global
> variable, of course, but that is no solution -- that's a problem waiting to
> happen.

It doesn't have to be a global. In a Python with late binding
defaults, this would work to get early binding:

def f(x=f.default_x):
    ...

f.default_x = something()

Of course, assignment to function attributes is a relatively modern
thing that is only permitted since Python 2.1, whereas function
defaults have been around since at least 1.4, so this wouldn't have
been an option when the semantics were being determined.


From framstag at rus.uni-stuttgart.de  Thu Nov 19 10:48:07 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 19 Nov 2015 15:48:07 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
Message-ID: <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de>

Terry Reedy <tjreedy at udel.edu> wrote:
> On 11/18/2015 11:50 AM, Ulli Horlacher wrote:
> > Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
> >
> >>          from Tkinter import Tk
> >>          from tkFileDialog import askopenfilename
> >>
> >>          Tk().withdraw()
> >>          file = askopenfilename()
> >
> > I found another glitch:
> >
> > After termination of askopenfilename() the window focus is not returned to
> > the calling window (xterm on Linux, cmd on Windows). I have to click it
> > again, to regain the focus and continue typing. Is there a workaround?
> 
> What happens with
> 
> root = Tk()
> root.withdraw()
> fiel = ...
> root.destroy()
> 
> Focus cannot stay with destroyed window.

The focus is moved to another, unrelated window, but not back to the
window in which the python scripts run. 
Same behaviour on Linux (XFCE) and windows 7.


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From torriem at gmail.com  Thu Nov 19 11:00:10 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 19 Nov 2015 09:00:10 -0700
Subject: Writing a Financial Services App in Python
In-Reply-To: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
Message-ID: <564DF20A.6060708@gmail.com>

On 11/19/2015 04:59 AM, Cai Gengyang wrote:
> 
> From YCombinator's new RFS, This is the problem I want to solve as it
> is a severe problem I face myself and something I need. I want to
> write this app in Python as I heard that Python is a great language
> that many programmers use ... How / where do I start ? The problem is
> detailed below :

I'm afraid you're going to be discouraged.

Well the first step is you have to learn programming.  And you don't
start with such a large problem, I assure you.  You start by learning
the language by following the tutorials, writing small programs to
become familiar with programming and the language itself.  Then you
become familiar with related things like algorithms and data structures,
and how to use them with and from Python (or any language).  Eventually
you add to that graphical user interface development.

After that then you might be in a position to start thinking about how
to design and build a program that does what you were talking about.

There honestly are no shortcuts.  Python is a great language, and is
easy to learn, but it's not like you can start cranking out full-blown
applications magically.  In the hands of experienced programmers, yes
Python is incredibly fast and flexible for cranking out working apps.

You might try checking out a Python application development framework
that can produce apps that will run on Android and iOS (and Windows and
Linux) called Kivy.  I would think mobile should be your target platform
for such an app.

> <snip>

> This seems to us like something software should help solve. We'd like
> to see teams tackling each of the component issues around saving and
> investing, along with ones tackling the entire package.

Are you wanting to contract with some programmers to create this
application for you?


From steve at pearwood.info  Thu Nov 19 11:01:27 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 20 Nov 2015 03:01:27 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
Message-ID: <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 12:19 am, BartC wrote:

> On 19/11/2015 12:19, Steven D'Aprano wrote:
>> On Thu, 19 Nov 2015 10:14 am, BartC wrote:
> 
>> Consider this pair of functions:
>>
>>
>> def expensive():
>>      # Simulate some expensive calculation or procedure.
>>      time.sleep(100)
>>      return random.randint(1, 6)
>>
>>
>> def demo(arg=expensive()):
>>      return arg + 1
[...]
> If someone /wants/ expensive() to be called each time, then why not? If
> they don't, then it seems easy enough to write:
> 
> demo_default=expensive()
> def demo(arg=demo_default):
> ...
> 
> (As you mention later...)

Yes, I mentioned it, and you seem to have failed to understand why that is a
horrible solution that causes more problems than it solves.

It breaks encapsulation -- data which belongs to the function has to be
stored outside the function, in a global variable, where just anybody or
anything could come along and modify it or delete it. It pollutes the
namespace -- imagine a module with twenty functions, each function having
four or five arguments that take default values. That's 80 to 100 global
variables, which all need to have unique names.

Yuck.


>> - if the language defaults to early binding, it is *easy* for the
>>    programmer to get late binding semantics;
>>
>> - if the language defaults to late binding, it is *very difficult*
>>    for the programmer to get early binding semantics.
> 
> I got the impression that Python was a nice, easy language for everyone
> to use. Not one where you need a Master's degree in CS to understand the
> nuances of! And to understand why something that is so blindingly
> obvious doesn't work.

Master's degree in CS, ha ha very funny. Not.

You know, for somebody who claims to design and implement your own
languages, you sometimes go to a remarkable effort to claim to be a dummy.
You write your own interpreter, but can't understand early versus late
binding? I don't think so.

I understand that the simplest things can be perplexing if you look at them
the wrong way. But we've explained multiply times now, or at least tried to
explain, that the argument default is a single object. That is blindingly
obvious once you look at it the right way, and it is a nice, clean design.
There's no need to introduce extra modes where code has to be stored away
to be evaluated later (apart from the body of the function itself).
Everything works the same way: assignment always evaluates a result and
binds it to the name, whether that assignment is in a parameter list or
not.

If you insist on thinking about it in terms of how C or Pascal work, of
course you will confuse yourself. The argument default is evaluated when
the function is created, and the resulting object is stored away for later
use, inside the function. That is clean and easy to understand.

I'm not saying that the behaviour with mutable defaults isn't surprising to
somebody coming from a completely different paradigm. I was surprised by it
too, the first time I got bitten. But surprising doesn't equal *wrong*. The
reason it was surprising to me was because I didn't think through the
implications of what I already knew. I knew the default value was
calculated once. I knew that the list was mutable. But I never put 2 and 2
together to get 4.

If you have a list which is created once, and modify it, the second time you
use it, it will be modified. Well duh. In hindsight, I shouldn't have been
surprised. The fact that I was is *my* failure.

It might be surprising the *first* time you see it, because you failed to
think it through. If you modify the object, *naturally* it will be
modified. Or if you failed to understand that the object was created once
and once only.

The interesting thing is, I've seen people write code *in the same program*
which assumed early binding in one function and late binding in another.
*Whichever* choice Python made, their program would have broken in one
place or the other. I don't believe that people have an inherent
expectation of one or the other. I believe that people expect whichever is
more convenient for them at the time, and get disappointed when it doesn't
work.


>> But let's try going the other way. Suppose function defaults were
>> evaluated each and every time you called the function. How could you
>> *avoid* the expense and waste of re-evaluating the default over and over
>> again?
> 
> I use default parameters a lot in other languages.
> 
> 99% of the time the default value is a constant.

Well, if it's a constant, then (apart from efficiency) early binding and
late binding makes *absolutely no difference*. Watch:


py> def demo_const(x, y=[]):
...     return x + len(y)
...
py> demo_const(5)
5
py> demo_const(5)
5

Exactly as you should expect. Where you run into trouble is when the default
value is NOT a constant:

py> def demo_variable(x, y=[]):
...     y.append(1)
...     return x + len(y)
...
py> demo_variable(5)
6
py> demo_variable(5)
7
py> demo_variable(5)
8


If you modify the value, the value will be modified. Why are you surprised
by this?



> And most often that constant is 0, "" or an empty list.
> 
> You want these very common examples to /just work/ instead of going to
> lengths trying to explain why they don't.

Ah, the good-old "I shouldn't have to think to understand programming" model
of programming. Because that works so well.



[...]
> Maybe you can wrap the entire module inside a function? Other than a bit
> at the end that calls that function. Does that solve the global lookup
> problem?

No.


>> When you deal with mutable objects, you have to expect them to mutate.
>> The whole point of mutability is that their value can change.
> 
> That [] doesn't look like an object that could change. 

Of course it does. It is a list literal, like int literals, float literals,
string literals and the rest. The only difference is that lists are mutable
and ints and strings are not.


> It looks like an 
> empty list constructor. You would expect a constructor for an empty list
> to yield an empty list throughout a program! (As it does, in most other
> contexts.)

You could write the function like this:

def test(arg=list()): 
    ... 

and it would make no difference. You could write it like this:

def test(arg=list() if isprime(104729) else "Surprise!"):
    ...

and you would still get the same result. In fact, you could even write it
like this:

if isprime(104729):
    def test(arg=[]):
        ...
else:
    def test(arg="Surprise!"):
        ...



> You presumably think differently because you have some inside knowledge
> of how Python works, and know that that [] undergoes a one-time
> assignment to a local, persistent 'default' variable where it's value
> can indeed by changed. (Thanks to another Python feature where an
> assignment is a very shallow copy of an object.) And it is that volatile
> variable that is the actual default.

Assignments are not copies at all.



-- 
Steven



From torriem at gmail.com  Thu Nov 19 11:07:27 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 19 Nov 2015 09:07:27 -0700
Subject: Writing a Financial Services App in Python
In-Reply-To: <b9f3883d-5e16-441d-9f57-79826cdc1d23@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
 <529622b6-3649-419d-a303-03e48d90c294@googlegroups.com>
 <b9f3883d-5e16-441d-9f57-79826cdc1d23@googlegroups.com>
Message-ID: <564DF3BF.4050508@gmail.com>

On 11/19/2015 08:24 AM, Cai Gengyang wrote:
> It will be a web-based application.

Contract it out.  Or attract people who are interested in making an open
source application.  What you are thinking of is a massive undertaking.

Web-based application design is even more complicated than desktop app
design.  Web development involves many different languages.  Requires a
working knowledge of:

- Python programming
- a web framework for processing events like Django or web2py or
something similar
- html
- css
- SQL
- Javascript, including jquery and probably others

To say nothing of the algorithms necessary to implement the trend
analysis you speak of.

> I for example, am a terrible trader because of having almost zero 
> discipline and thus keep losing money.

Something tells me if the people you're trying to help have zero
discipline, then I don't think software is really going to help them.
Computers are just tools.


From boblatest at yahoo.com  Thu Nov 19 11:13:44 2015
From: boblatest at yahoo.com (Robert Latest)
Date: 19 Nov 2015 16:13:44 GMT
Subject: Why doesn't this method have access to its "self" argument?
Message-ID: <db6apoFgvjlU1@mid.individual.net>

Hi all,

I'm still trying to find a simple way to implement a method (but not the
full class) in C. Suggestions I have recived so far are good, but seem to be
over the top for such a (seemingly) simple problem. I came up with the idea
of implementing the class in Python, and just setting the method after the
actual class definition. See example below. The "py_method" is added to the
class later on, and it seems to become a proper method of the class (and its
instances) just as if it had been defined inside the class itself. Of course
it also has access to its "self" argument.

If I do the same thing with a method implemented in the external module
"cmethod", and I call that method on an instance, it gets passed a NULL
pointer as its "self" argument and so has no access to the instance's "data"
attribute.

I found a workaround using a wrapper method which calls a C function,
passing the instance as a separate argument. It works, and I cannot see any
disadvantage. It's just not as elegant as I'd like it to be, and I don't
understand WHY the C "method" doesn't receive a pointer to the Python
instance. Maybe somebody can clarify.


Here's what happens when I build, install and run the minimal example below:

rl at dc:~/c/cwsf/python_module$ python test.py
py_method(): <__main__.Test instance at 0xb71f5a2c>
c_method(): self at (nil)
c_function(): self at (nil), instance at 0xb71f5a2c
<__main__.Test instance at 0xb71f5a2c>
'Some data'
c_function(): self at (nil), instance at 0xb71f5a2c
<__main__.Test instance at 0xb71f5a2c>
'New Data'
rl at dc:~/c/cwsf/python_module$

Minimal example files:


========================== test.py ===================================

import cmethod

class Test():
    def __init__(self):
        self.data = "Some data"

    def wrapper(self):
        return cmethod.c_function(self)

def py_method(self):
    print "py_method(): %s" % repr(self)

# add methods to the class "after the fact"
Test.py_method = py_method
Test.c_method = cmethod.c_method

foo = Test()
foo.py_method() # works as expected
foo.c_method()  # is passed NULL in its self argument, why?
foo.wrapper()   # works fine, updates "data" attribute
foo.wrapper()   # works fine, sees updated "data" attribute

==================== cmethod.c =======================================

#include <Python.h>
#include <stdio.h>

static PyObject *c_method(PyObject *self, PyObject *args) {
    (void) args; /* not used */
    fprintf(stderr, "c_method(): self at %p\n",
        (void*) self); /* always prints 0x0 */
    Py_INCREF(Py_None);
    return Py_None;
}

static PyObject *c_function(PyObject *self, PyObject *args) {
    PyObject *instance;
    PyObject *o;
    /* Retrieve instance from wrapper through argument tuple: WORKS */
    PyArg_UnpackTuple(args, "c_function", 1, 1, &instance);
    fprintf(stderr, "c_function(): self at %p, instance at %p\n",
        (void*) self, (void*) instance);
    PyObject_Print(instance, stderr, 0); fputc('\n', stderr);
    /* Get and set attributes of instance: WORKS */
    o = PyObject_GetAttrString(instance, "data");
    PyObject_Print(o, stderr, 0); fputc('\n', stderr);
    PyObject_SetAttrString(instance, "data",
        PyString_FromString("New Data"));
    /* Side question: Do I have to DECREF "o"? */
    Py_INCREF(Py_None);
    return Py_None;
}

static PyMethodDef methods[] =
{
     {"c_method", c_method, METH_VARARGS, "I want to be a class method"},
     {"c_function", c_function, METH_VARARGS, "I am a function"},
     {NULL, NULL, 0, NULL}
};

PyMODINIT_FUNC initcmethod(void)
{
     (void) Py_InitModule("cmethod", methods);
}


======================== setup_cmethod.py ===========================

from distutils.core import setup, Extension

module1 = Extension('cmethod', sources = ['cmethod.c'])

setup (name = 'cmethod',
        version = '0.1',
        description = 'struggling to implement a class method in C',
        ext_modules = [module1])


robert


From gengyangcai at gmail.com  Thu Nov 19 11:20:06 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Thu, 19 Nov 2015 08:20:06 -0800 (PST)
Subject: Writing a Financial Services App in Python
In-Reply-To: <mailman.466.1447948821.16136.python-list@python.org>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
 <mailman.466.1447948821.16136.python-list@python.org>
Message-ID: <d4003748-23df-4c8a-a9f4-b2ccbe440457@googlegroups.com>

Sure ... is this : https://www.codecademy.com/learn/python a good place to learn Python ?

Are you wanting to contract with some programmers to create this application for you? ---- Eventually I will have to find programming co-founders and employees to create and iterate the product as user feedback streams in. But I will write the initial prototype myself because I plan to be the main programmer / founder , but yes ... eventually I will need 1 or even 2 co-founders and when the platform gains enough users, we will have to hire programmers and sales/ business people. But this will be a tech-heavy company and all the main founders and employees should be excellent programmers. But for the moment, I plan to write the initial prototype myself ... 


On Friday, November 20, 2015 at 12:00:34 AM UTC+8, Michael Torrie wrote:
> On 11/19/2015 04:59 AM, Cai Gengyang wrote:
> > 
> > From YCombinator's new RFS, This is the problem I want to solve as it
> > is a severe problem I face myself and something I need. I want to
> > write this app in Python as I heard that Python is a great language
> > that many programmers use ... How / where do I start ? The problem is
> > detailed below :
> 
> I'm afraid you're going to be discouraged.
> 
> Well the first step is you have to learn programming.  And you don't
> start with such a large problem, I assure you.  You start by learning
> the language by following the tutorials, writing small programs to
> become familiar with programming and the language itself.  Then you
> become familiar with related things like algorithms and data structures,
> and how to use them with and from Python (or any language).  Eventually
> you add to that graphical user interface development.
> 
> After that then you might be in a position to start thinking about how
> to design and build a program that does what you were talking about.
> 
> There honestly are no shortcuts.  Python is a great language, and is
> easy to learn, but it's not like you can start cranking out full-blown
> applications magically.  In the hands of experienced programmers, yes
> Python is incredibly fast and flexible for cranking out working apps.
> 
> You might try checking out a Python application development framework
> that can produce apps that will run on Android and iOS (and Windows and
> Linux) called Kivy.  I would think mobile should be your target platform
> for such an app.
> 
> > <snip>
> 
> > This seems to us like something software should help solve. We'd like
> > to see teams tackling each of the component issues around saving and
> > investing, along with ones tackling the entire package.
> 
> Are you wanting to contract with some programmers to create this
> application for you?


From breamoreboy at yahoo.co.uk  Thu Nov 19 11:26:01 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 19 Nov 2015 16:26:01 +0000
Subject: Is there an meaning of '[[]]' in a list?
In-Reply-To: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
Message-ID: <n2kt7c$ds$1@ger.gmane.org>

On 19/11/2015 11:28, fl wrote:
> Hi,
> In the previous exercises, I see list:
> cc=[[],[],[]]
>
> Then, I can have this:
>
> ccc=[[[]],[[]],[[]]]
>
> I can also have
>
> ccc[0]
> Out[158]: [[]]
>
> ccc[0]='o'
>
> ccc
> Out[163]: ['o', [[]], [[]]]
>
>
> I have question: Is there any difference between [[]] and []?
> [[]] can have deeper assignment and use than
>
> ccc[0]='o'
>
>
> Thanks,
>

I have question.  Is there any chance that you stop wasting the time of 
people on this list by either doing your own research or trying things 
at an interactive prompt?  Or are you now well past that point, as 
you're learned that the extremely generous people here have fitted your 
bibs, spoon fed you and and changed your nappies so many times that it 
has rendered you incapable of doing anything for yourself?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From torriem at gmail.com  Thu Nov 19 11:31:10 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 19 Nov 2015 09:31:10 -0700
Subject: non-blocking getkey?
In-Reply-To: <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de>
Message-ID: <564DF94E.8020302@gmail.com>

On 11/19/2015 08:48 AM, Ulli Horlacher wrote:
> 
> The focus is moved to another, unrelated window, but not back to the
> window in which the python scripts run. 
> Same behaviour on Linux (XFCE) and windows 7.

That's because an app that communicates with standard in and standard
out could be running over telnet, theoretically, so there would be no
window at all. There's absolutely no link in stdin and stdout to a
graphical window.  It's not even possible on Windows as the console
subsystem is completely separate from the GUI subsystem.  When your app
opens a Tk window, it's creating a brand new, top-level window, not
associated with any existing window.

One windows it might be possible to use the win32 api to enumerate the
windows, find your console window and switch to it.   Might even be
possible on Linux using raw X11 calls.









From torriem at gmail.com  Thu Nov 19 12:25:08 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 19 Nov 2015 10:25:08 -0700
Subject: Writing a Financial Services App in Python
In-Reply-To: <d4003748-23df-4c8a-a9f4-b2ccbe440457@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
 <mailman.466.1447948821.16136.python-list@python.org>
 <d4003748-23df-4c8a-a9f4-b2ccbe440457@googlegroups.com>
Message-ID: <564E05F4.6010809@gmail.com>

On 11/19/2015 09:20 AM, Cai Gengyang wrote:
> Sure ... is this : https://www.codecademy.com/learn/python a good
> place to learn Python ?

Why not have a look first at the many tutorials, including the ones on
Python's web site?  You need to explore feasibility first before you go
too far. Python is not the only language out there. I happen to like it,
but there are other popular choices.  An experienced developer can pick
up and program in any language very quickly.

Also you need to know a lot more than just programming in Python.  You
will need to know the various web development technologies and languages.

I don't say this just to discourage you up front.  I say this from a lot
of sad experience.  Your goals are *very* ambitious.  I've seen fairly
straightforward web apps stretch out into years and many tens of
thousands of dollars with whole teams of programmers.  And it does not
appear you have any programming experience at all yet.

Forget about a web app for now.  Work on the pieces like the algorithms
needed for doing the analysis you require.  Do some simple programs that
only do console input and output.

> Are you wanting to contract with some programmers to create this
> application for you? ---- Eventually I will have to find programming
> co-founders and employees to create and iterate the product as user
> feedback streams in. But I will write the initial prototype myself
> because I plan to be the main programmer / founder , but yes ...
> eventually I will need 1 or even 2 co-founders and when the platform
> gains enough users, we will have to hire programmers and sales/
> business people. But this will be a tech-heavy company and all the
> main founders and employees should be excellent programmers. But for
> the moment, I plan to write the initial prototype myself ...

Sounds ambitious! Hope you have a business plan in mind from the start.


From rosuav at gmail.com  Thu Nov 19 12:30:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 04:30:26 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmo0+acJL5bCDui3RSOSADN++oJFWwNrmFes7mve_8ghVw@mail.gmail.com>

On Fri, Nov 20, 2015 at 3:01 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> You know, for somebody who claims to design and implement your own
> languages, you sometimes go to a remarkable effort to claim to be a dummy.
> You write your own interpreter, but can't understand early versus late
> binding? I don't think so.

I'm not sure that's such a fair comparison. Anyone can design a
brand-new language, and even implementing one isn't all that hard. If
you don't understand other languages, you can certainly create the one
that always does what you think most intuitive, right at the instant
when you designed/implemented some feature. What's hard is designing a
clean language that does what _someone else_ expects. (And that
includes yourself in six months.)

ChrisA


From bc at freeuk.com  Thu Nov 19 12:30:43 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 17:30:43 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2l0s3$5l6$1@dont-email.me>

On 19/11/2015 16:01, Steven D'Aprano wrote:
> On Fri, 20 Nov 2015 12:19 am, BartC wrote:

> You know, for somebody who claims to design and implement your own
> languages, you sometimes go to a remarkable effort to claim to be a dummy.
> You write your own interpreter, but can't understand early versus late
> binding? I don't think so.

No I don't; so? Maybe my interpreter can do its thing without being 
aware that what it's doing has been called 'late binding' or 'early 
binding' by someone else.

At least its default values work as expected! (And they can also be 
applied to existing external functions. Even C API functions where the 
implementation doesn't support these features.

So if an argument is missing, it applies the default I specify in its 
place. It's that simple.)

> I understand that the simplest things can be perplexing if you look at them
> the wrong way. But we've explained multiply times now, or at least tried to
> explain, that the argument default is a single object. That is blindingly
> obvious once you look at it the right way, and it is a nice, clean design.

I can understand now how it works as it does. But I still think it is 
unintuitive. A language design could have chosen to make it work however 
it liked.

> There's no need to introduce extra modes where code has to be stored away
> to be evaluated later (apart from the body of the function itself).
> Everything works the same way: assignment always evaluates a result and
> binds it to the name, whether that assignment is in a parameter list or
> not.
>
> If you insist on thinking about it in terms of how C or Pascal work, of
> course you will confuse yourself. The argument default is evaluated when
> the function is created, and the resulting object is stored away for later
> use, inside the function. That is clean and easy to understand.
>
> I'm not saying that the behaviour with mutable defaults

The whole concept of 'mutable' default is alien to me. A default is just 
a convenient device to avoid having to write:

   fn(0) or fn("") or fn([])

You just write fn() instead. But it shouldn't come at the cost of 
completely different semantics! Because then it can't really be called a 
default value at all.

  isn't surprising to
> somebody coming from a completely different paradigm. I was surprised by it
> too, the first time I got bitten.

So you didn't bother reading the LRM either!

> py> def demo_const(x, y=[]):
> ...     return x + len(y)

> Exactly as you should expect. Where you run into trouble is when the default
> value is NOT a constant:
>
> py> def demo_variable(x, y=[]):
> ...     y.append(1)
> ...     return x + len(y)

Sorry, what is the default value in each of these? As the first lines of 
the defintions look identical apart from the function names.

> ...
> py> demo_variable(5)
> 6
> py> demo_variable(5)
> 7
> py> demo_variable(5)
> 8
>
>
> If you modify the value, the value will be modified. Why are you surprised
> by this?

Which value is being modified? The []?

>> And most often that constant is 0, "" or an empty list.
>>
>> You want these very common examples to /just work/ instead of going to
>> lengths trying to explain why they don't.
>
> Ah, the good-old "I shouldn't have to think to understand programming" model
> of programming. Because that works so well.

It works well when sharing code because not everyone understands things 
at the same level.

>> Maybe you can wrap the entire module inside a function? Other than a bit
>> at the end that calls that function. Does that solve the global lookup
>> problem?
>
> No.

Why not?

>
>>> When you deal with mutable objects, you have to expect them to mutate.
>>> The whole point of mutability is that their value can change.
>>
>> That [] doesn't look like an object that could change.
>
> Of course it does.

You've lost me know.

Are you saying that:

   a=[]

why sometimes not assign an empty list, because that [] could have been 
modified?

It is a list literal, like int literals, float literals,
> string literals and the rest.

Another surprise? Literals by definition can't change:

def fn():
	a=[10,20,30]
	a.append(999)

I would hope that a is set to [10,20,30] at each entry to the function!

>> You presumably think differently because you have some inside knowledge
>> of how Python works, and know that that [] undergoes a one-time
>> assignment to a local, persistent 'default' variable where it's value
>> can indeed by changed. (Thanks to another Python feature where an
>> assignment is a very shallow copy of an object.) And it is that volatile
>> variable that is the actual default.
>
> Assignments are not copies at all.

if you write A=B then something of B needs to have been copied into A, 
even if it's just the reference that B contains. Otherwise it would be 
difficult to get A to refer to the same object as B.

-- 
Bartc


From rosuav at gmail.com  Thu Nov 19 12:34:29 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 04:34:29 +1100
Subject: Why doesn't this method have access to its "self" argument?
In-Reply-To: <db6apoFgvjlU1@mid.individual.net>
References: <db6apoFgvjlU1@mid.individual.net>
Message-ID: <CAPTjJmoc-nGbW0pteJnKTR=-6r-Fyv1C2Ei=keLNO_mJnQoZ2Q@mail.gmail.com>

On Fri, Nov 20, 2015 at 3:13 AM, Robert Latest via Python-list
<python-list at python.org> wrote:
> rl at dc:~/c/cwsf/python_module$ python test.py
>
> Minimal example files:
>
> ========================== test.py ===================================
>
> import cmethod
>
> class Test():
>
> # add methods to the class "after the fact"
> Test.py_method = py_method
> Test.c_method = cmethod.c_method

Are you using Python 2 here? If so, you're using an old-style class,
which has specific consequences that I can never remember. Does the
situation change if you slap 'object' between those parentheses? Or if
you use Python 3?

ChrisA


From rosuav at gmail.com  Thu Nov 19 12:45:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 04:45:14 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l0s3$5l6$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
Message-ID: <CAPTjJmrjjw=kQtC-dSOhETsbkSzZFXKzSM3hEmsc_6sFNH-gQw@mail.gmail.com>

On Fri, Nov 20, 2015 at 4:30 AM, BartC <bc at freeuk.com> wrote:
> The whole concept of 'mutable' default is alien to me. A default is just a
> convenient device to avoid having to write:
>
>   fn(0) or fn("") or fn([])
>
> You just write fn() instead. But it shouldn't come at the cost of completely
> different semantics! Because then it can't really be called a default value
> at all.
>

Do you understand the concept of "mutable objects"? Don't even try to
discuss mutable function defaults until you do.

If your language simply has no mutable objects, then sure, it's easy
to understand function defaults! There's no such thing as early or
late binding; in fact, you can even super-late-bind, where you don't
actually call a function until its *return value* is being used (as
long as that function has no side effects). But as soon as objects are
capable of retaining their identities while changing their values, you
need an object model that (a) distinguishes between identity and
value, and (b) allows some definition of early or late binding,
because it *will* matter.

> if you write A=B then something of B needs to have been copied into
> A, even if it's just the reference that B contains. Otherwise it would be
> difficult to get A to refer to the same object as B.

Please, PLEASE, go and read/watch Ned's PyCon talk (the one I linked
you to earlier). Don't post another word on this subject until you
comprehend what he is saying.

ChrisA


From __peter__ at web.de  Thu Nov 19 13:00:15 2015
From: __peter__ at web.de (Peter Otten)
Date: Thu, 19 Nov 2015 19:00:15 +0100
Subject: Why doesn't this method have access to its "self" argument?
References: <db6apoFgvjlU1@mid.individual.net>
Message-ID: <n2l2ni$u2n$1@ger.gmane.org>

Robert Latest via Python-list wrote:

> I found a workaround using a wrapper method which calls a C function,
> passing the instance as a separate argument. It works, and I cannot see
> any disadvantage. It's just not as elegant as I'd like it to be, and I
> don't understand WHY the C "method" doesn't receive a pointer to the
> Python instance. Maybe somebody can clarify.

I don't know much about the C-implementation side, but functions written in 
Python are also descriptors. Given

def f(self): pass

class A(object):
    m = f
    c = abs
    v = 42

a = A()

a seemingly simple attribute access

m = a.m      # m is now a bound method

invokes f.__get__(a, A) under the hood while

m = a.c
assert m is abs

just returns the function (abs in the example) the same way it returns any 
other value:

v = a.v
assert v == 42




From bc at freeuk.com  Thu Nov 19 13:19:26 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 18:19:26 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.473.1447955117.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
Message-ID: <n2l3ne$hbp$1@dont-email.me>

On 19/11/2015 17:45, Chris Angelico wrote:
> On Fri, Nov 20, 2015 at 4:30 AM, BartC <bc at freeuk.com> wrote:
>> The whole concept of 'mutable' default is alien to me. A default is just a
>> convenient device to avoid having to write:
>>
>>    fn(0) or fn("") or fn([])
>>
>> You just write fn() instead. But it shouldn't come at the cost of completely
>> different semantics! Because then it can't really be called a default value
>> at all.
>>
>
> Do you understand the concept of "mutable objects"? Don't even try to
> discuss mutable function defaults until you do.

Yes. In the languages I create, pretty much everything is mutable, 
provided it can supply an l-value. Constructs such as those for empty 
lists ([] in Python, () in mine) aren't l-values.

But it doesn't apply default values. The language is very different 
however, because the byte-code compiler always has full knowledge of 
functions that are called directly. Then it knows when an argument is 
omitted, and can simply substitute the expression used as the default.

> If your language simply has no mutable objects, then sure, it's easy
> to understand function defaults! There's no such thing as early or
> late binding; in fact, you can even super-late-bind, where you don't
> actually call a function until its *return value* is being used (as
> long as that function has no side effects). But as soon as objects are
> capable of retaining their identities while changing their values, you
> need an object model that (a) distinguishes between identity and
> value, and (b) allows some definition of early or late binding,
> because it *will* matter.
>
>> if you write A=B then something of B needs to have been copied into
>> A, even if it's just the reference that B contains. Otherwise it would be
>> difficult to get A to refer to the same object as B.
>
> Please, PLEASE, go and read/watch Ned's PyCon talk (the one I linked
> you to earlier). Don't post another word on this subject until you
> comprehend what he is saying.

I looked through the long article (I don't remember seeing a link to a 
video), and followed it up to about 3/4 of the way through, then it got 
a bit heavy.

But what is it about my remarks above that isn't right?

-- 
Bartc


From breamoreboy at yahoo.co.uk  Thu Nov 19 13:20:34 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 19 Nov 2015 18:20:34 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l0s3$5l6$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
Message-ID: <n2l3u5$i6a$1@ger.gmane.org>

On 19/11/2015 17:30, BartC wrote:
> On 19/11/2015 16:01, Steven D'Aprano wrote:
>> On Fri, 20 Nov 2015 12:19 am, BartC wrote:
>
>> You know, for somebody who claims to design and implement your own
>> languages, you sometimes go to a remarkable effort to claim to be a
>> dummy.
>> You write your own interpreter, but can't understand early versus late
>> binding? I don't think so.
>
> No I don't; so? Maybe my interpreter can do its thing without being
> aware that what it's doing has been called 'late binding' or 'early
> binding' by someone else.
>
> At least its default values work as expected!
>

Python's default values work exactly as I expect as the subject has been 
debated at least twice a year on c.l.py for the 15 or so years that I've 
been using Python.  If your expectations are clearly wrong, that is your 
problem and your problem alone.  A solution to your problem is another 
language that does meet all of your expectations, but as there is never 
a "one size fits all" the only one that I can think of is your own, 
whatever that is called.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From breamoreboy at yahoo.co.uk  Thu Nov 19 13:26:08 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 19 Nov 2015 18:26:08 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l3ne$hbp$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
Message-ID: <n2l48j$o2d$1@ger.gmane.org>

On 19/11/2015 18:19, BartC wrote:
> On 19/11/2015 17:45, Chris Angelico wrote:
>> On Fri, Nov 20, 2015 at 4:30 AM, BartC <bc at freeuk.com> wrote:
>>> The whole concept of 'mutable' default is alien to me. A default is
>>> just a
>>> convenient device to avoid having to write:
>>>
>>>    fn(0) or fn("") or fn([])
>>>
>>> You just write fn() instead. But it shouldn't come at the cost of
>>> completely
>>> different semantics! Because then it can't really be called a default
>>> value
>>> at all.
>>>
>>
>> Do you understand the concept of "mutable objects"? Don't even try to
>> discuss mutable function defaults until you do.
>
> Yes. In the languages I create, pretty much everything is mutable,
> provided it can supply an l-value. Constructs such as those for empty
> lists ([] in Python, () in mine) aren't l-values.
>
> But it doesn't apply default values. The language is very different
> however, because the byte-code compiler always has full knowledge of
> functions that are called directly. Then it knows when an argument is
> omitted, and can simply substitute the expression used as the default.
>
>> If your language simply has no mutable objects, then sure, it's easy
>> to understand function defaults! There's no such thing as early or
>> late binding; in fact, you can even super-late-bind, where you don't
>> actually call a function until its *return value* is being used (as
>> long as that function has no side effects). But as soon as objects are
>> capable of retaining their identities while changing their values, you
>> need an object model that (a) distinguishes between identity and
>> value, and (b) allows some definition of early or late binding,
>> because it *will* matter.
>>
>>> if you write A=B then something of B needs to have been copied into
>>> A, even if it's just the reference that B contains. Otherwise it
>>> would be
>>> difficult to get A to refer to the same object as B.
>>
>> Please, PLEASE, go and read/watch Ned's PyCon talk (the one I linked
>> you to earlier). Don't post another word on this subject until you
>> comprehend what he is saying.
>
> I looked through the long article (I don't remember seeing a link to a
> video), and followed it up to about 3/4 of the way through, then it got
> a bit heavy.
>
> But what is it about my remarks above that isn't right?
>

To summarize, it once again shows that you haven't got the faintest idea 
what you're talking about.  You're now in a very exclusive club with the 
RUE and Nick the Greek, the world's leading webmaster.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From marko at pacujo.net  Thu Nov 19 13:39:38 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 19 Nov 2015 20:39:38 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
Message-ID: <87mvu9esut.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> Yes. In the languages I create, pretty much everything is mutable,
> provided it can supply an l-value. Constructs such as those for empty
> lists ([] in Python, () in mine) aren't l-values.
>
> But it doesn't apply default values.

Python's default-value semantics is analogous to C++:

========================================================================
#include <iostream>

using namespace std;

static int z;

static void f(int &x = z)
{
    x++;
}

int main()
{
    cout << z << endl;
    f();
    cout << z << endl;
    f();
    cout << z << endl;
    return 0;
}
========================================================================

which prints:

    0
    1
    2


Marko


From ian.g.kelly at gmail.com  Thu Nov 19 13:42:46 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 11:42:46 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l48j$o2d$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me> <n2l48j$o2d$1@ger.gmane.org>
Message-ID: <CALwzid=2VG5x-qgAJx4m+KWTJx6OcWo29wwprucL5+B44OtAcg@mail.gmail.com>

On Thu, Nov 19, 2015 at 11:26 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> To summarize, it once again shows that you haven't got the faintest idea
> what you're talking about.  You're now in a very exclusive club with the RUE
> and Nick the Greek, the world's leading webmaster.

Eh. Ranting Rick and Mark Janssen / Zipher / TheDoctor / whatever name
he's using now belong in that club, but Nikos was just incompetent,
not a crackpot.

BartC on the other hand is just complaining about an aspect of Python
that is legitimately controversial.


From oscar.j.benjamin at gmail.com  Thu Nov 19 13:44:50 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Thu, 19 Nov 2015 18:44:50 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l3ne$hbp$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
Message-ID: <CAHVvXxTXfb-R0b+qcQJWcRXmtN14_fWZBifhLV-C0yy-ghaQFg@mail.gmail.com>

On 19 November 2015 at 18:19, BartC <bc at freeuk.com> wrote:
>>>
>>> if you write A=B then something of B needs to have been copied into
>>> A, even if it's just the reference that B contains. Otherwise it would be
>>> difficult to get A to refer to the same object as B.
>>
>> Please, PLEASE, go and read/watch Ned's PyCon talk (the one I linked
>> you to earlier). Don't post another word on this subject until you
>> comprehend what he is saying.
>
> I looked through the long article (I don't remember seeing a link to a
> video), and followed it up to about 3/4 of the way through, then it got a
> bit heavy.
>
> But what is it about my remarks above that isn't right?

It's not necessarily incorrect (just focussing on the remark quoted
above) but you'll find it easier to understand the model if you adopt
the same terminology that is usually used. When talking of "copying"
in a Python context something different is implied than what happens
with A=B.

The statement A=B (assuming A and B are names and not expressions)
simply binds the name A to the same object that the name B is bound
to. In the implementation of CPython the names are associated with
pointers and the value of the pointer associated with B is copied to
the pointer associated with A. Another implementation may not use
pointers but there will in some way be a "reference" that is "copied"
over if you like to view it that way.

However in a Python context when someone talks of "copying" they will
mean something different: creating a new object which is distinct
from, but has the same value as, some previously existing object. It
is important in Python to distinguish between operations that
create/mutate objects and operations that rebind names. This
distinction has semantic implications that are not hard to understand
if you think about them carefully and consistent use of terminology
really helps.

--
Oscar


From bc at freeuk.com  Thu Nov 19 13:50:15 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 18:50:15 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.476.1447957612.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
Message-ID: <n2l5h7$p1u$1@dont-email.me>

On 19/11/2015 18:26, Mark Lawrence wrote:
> On 19/11/2015 18:19, BartC wrote:

>>>> if you write A=B then something of B needs to have been copied into
>>>> A, even if it's just the reference that B contains. Otherwise it
>>>> would be
>>>> difficult to get A to refer to the same object as B.
>>>
>>> Please, PLEASE, go and read/watch Ned's PyCon talk (the one I linked
>>> you to earlier). Don't post another word on this subject until you
>>> comprehend what he is saying.
>

>> But what is it about my remarks above that isn't right?

>
> To summarize, it once again shows that you haven't got the faintest idea
> what you're talking about.

But you're not going to tell me what it is I got wrong!

I said that Python's "=" does a very shallow copy. And I stated that in 
A=B, something of B must be copied into A.

I (and probably others) would like to know why none of that is correct. 
But I suspect I'm not wrong.


-- 
Bartc




From rosuav at gmail.com  Thu Nov 19 14:09:49 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 06:09:49 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l5h7$p1u$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
Message-ID: <CAPTjJmrxm5LiBgDKDkcihN4PjmrQbMPd3dFPaMyX5L02P-7uLw@mail.gmail.com>

On Fri, Nov 20, 2015 at 5:50 AM, BartC <bc at freeuk.com> wrote:
> But you're not going to tell me what it is I got wrong!
>
> I said that Python's "=" does a very shallow copy. And I stated that in A=B,
> something of B must be copied into A.
>
> I (and probably others) would like to know why none of that is correct. But
> I suspect I'm not wrong.

There's no copying happening. You evaluate the expression `B`, and get
back some kind of object (because all expressions in Python evaluate
to objects, unless they raise exceptions or in some way don't finish
evaluating). The name A then becomes bound to that object. You're not
copying a reference; you're simply referencing the result of an
expression.

PLEASE finish reading Ned's talk. Here's the link again:

http://nedbatchelder.com/text/names1.html

It is an excellent explanation of the exact points you're confused about.

ChrisA


From patrickhess at gmx.net  Thu Nov 19 14:17:37 2015
From: patrickhess at gmx.net (Patrick Hess)
Date: Thu, 19 Nov 2015 20:17:37 +0100
Subject: How can I export data from a website and write the contents to a
 text file?
In-Reply-To: <e0edf996-9ce8-404e-b4e0-1e9a7b9af706@googlegroups.com>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>
 <e0edf996-9ce8-404e-b4e0-1e9a7b9af706@googlegroups.com>
Message-ID: <2052054.MEiq1cOQgg@desk8.phess.net>

ryguy7272 wrote:
> text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
> [...]
> It doesn't seem like the '\n' is doing anything useful.  All the text is jumbled together.
> [...]
> I finally got it working.  It's like this:
> "\r\n"

The better solution would be to open text files in actual text mode:

    open("filename", "wb")   # binary mode
    open("filename", "w")    # text mode

In text mode, the correct line-ending characters, which will vary
depending on the operating system, are chosen automatically.

    with open("test.txt", "w") as textfile:
        textfile.write("line 1\n")
        textfile.write("line 2")

This produces "line 1\nline 2" on Unix systems and "line 1\r\nline 2"
on Windows.

Also involves less typing this way. ;-)

Patrick


From rosuav at gmail.com  Thu Nov 19 14:19:06 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 06:19:06 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l3ne$hbp$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
Message-ID: <CAPTjJmoNvZSy4vncdGpD7h81uF+xCyXEVp5XB6d84gQ+Mk_0Nw@mail.gmail.com>

On Fri, Nov 20, 2015 at 5:19 AM, BartC <bc at freeuk.com> wrote:
> Yes. In the languages I create, pretty much everything is mutable, provided
> it can supply an l-value. Constructs such as those for empty lists ([] in
> Python, () in mine) aren't l-values.
>
> But it doesn't apply default values. The language is very different however,
> because the byte-code compiler always has full knowledge of functions that
> are called directly. Then it knows when an argument is omitted, and can
> simply substitute the expression used as the default.

In other words, your language uses late binding by default. That's
fine; it's a design choice that you've made one way and Python's made
the other way. It's on par with design choices like whether adding a
string and an integer implicitly stringifies the int, or raises an
error. I know several good languages that have taken each of those
choices.

But every choice has consequences. Steven gave you a few examples of
the consequences of late-binding default arguments. For example, can
you translate this into (one of) your language(s), and explain the
semantics of the late binding?

# scope 1: can be a module, an inner function, whatever
y = 42
def func(x=y):
    return x
def change_y():
    global y # affect the one in this scope
    y = 28

# scope 2: another module/function/etc
from scope1 import func # gain access, however that's done

change_y()
y = 7
func()


Should this return 7, 28, or 42? Early binding demands 42, which is
nice and simple: you don't need to look anywhere outside the
function's own definition to grok its defaults. The default is stable
(it won't change from one run to another - it'll always be the same
object). Scope-recognizing late binding would use 28; it re-evaluates
the expression 'y' in its original scope. This one makes the most
sense to me, of all late-bind semantics; it also happens to be the
same semantics as you get if you do the classic "if x is None: x=y"
late-bind in Python, modulo the effect of the nested scope. But you're
saying that it "simply substitute[s] the expression", which would mean
that "func()" is exactly the same as "func(y)". A function default
argument is therefore able to STEAL STUFF FROM THE CALLER'S SCOPE.
Sorry for shouting, but if that ain't bizarre, I don't know what is.

ChrisA


From ian.g.kelly at gmail.com  Thu Nov 19 14:25:21 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 12:25:21 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmoNvZSy4vncdGpD7h81uF+xCyXEVp5XB6d84gQ+Mk_0Nw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <CAPTjJmoNvZSy4vncdGpD7h81uF+xCyXEVp5XB6d84gQ+Mk_0Nw@mail.gmail.com>
Message-ID: <CALwzid=WYTcv8NthnERa8YiSzqL4YhcsWq51POp29ZT9FqFB-g@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:19 PM, Chris Angelico <rosuav at gmail.com> wrote:
> But you're
> saying that it "simply substitute[s] the expression", which would mean
> that "func()" is exactly the same as "func(y)". A function default
> argument is therefore able to STEAL STUFF FROM THE CALLER'S SCOPE.
> Sorry for shouting, but if that ain't bizarre, I don't know what is.

It's like pass-by-name, but in reverse.


From skaufman at tsi.com  Thu Nov 19 14:45:41 2015
From: skaufman at tsi.com (Kaufman, Stan)
Date: Thu, 19 Nov 2015 19:45:41 +0000
Subject: Unsuccessful installation
Message-ID: <4530f633821e477798c80bf8d6d095f2@TSI-SV-MBX-01.tsi.corp.com>

Python would not run on this Windows XP computer.  After four  attempts at "change/remove" it still gives the same message:

[cid:image001.png at 01D122D0.93CC3270]

The first trip through "change/remove" appeared to be a further step in installation.  The second through fourth trips indicated "repairing..."  Each time, an attempt to run it resulted in the above message.




---------------------------------------
Stan Kaufman
Principal Scientist (retired)
TSI Incorporated
500 Cardigan Road
St. Paul, MN 55126

---------------------------------------
"Science is what we have learned about how to keep from fooling ourselves."
Richard Feynman
---------------------------------------


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From rosuav at gmail.com  Thu Nov 19 14:46:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 06:46:42 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
Message-ID: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>

On Fri, Nov 20, 2015 at 5:42 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> BartC on the other hand is just complaining about an aspect of Python
> that is legitimately controversial.

IMO it's controversial mainly because there's an easy and obvious
syntax for early binding, but late binding doesn't have syntactic
support, and all the options are imperfect. Consider:

def late1(x=None):
    """Terse but buggy"""
    do_stuff_with(x or [])

def late2(x=None):
    """Not bad but has an extra line for each default. Also, can't take None."""
    if x is None: x = []
    do_stuff_with(x)

_SENTINEL = object()
def late3(x=_SENTINEL):
    """Has the same global-pollution problem you get when you
    try to construct early binding from late; you can share the
    sentinel among multiple args, even multiple funcs, though"""
    if x is _SENTINEL: x = []
    do_stuff_with(x)

def late4(x=object()):
    """Depends on its own name remaining bound in its scope,
    and will break if you change argument order"""
    if x is late4.__defaults__[0]: x = []
    do_stuff_with(x)

And there might be other techniques, too. They all share one important
flaw, too: When you ask for help about the function, you can't see
what the default really is. All you see is:

late1(x=None)
late3(x=<object object at 0x7f7a80b3a080>)

In the first two cases, it's not too bad; you can specify a timeout as
either a number or as None, and if it's None (the default), the
timeout is three times the currently estimated round trip time. No
problem. But how would you implement something like next() in pure
Python? If you provide _any second argument at all_, it returns that
instead of raising StopIteration. The ONLY way that I can think of is
to use *args notation:

def next(iterator, *default):
    try:
        return iterator.__next__()
    except StopIteration:
        if default: return default[0]
        raise

And while that isn't TOO bad for just one argument, it scales poorly:

def foo(fixed_arg, *args):
    """Foo the fixed_arg against the spam mapping, the
    ham sequence, and the jam file."""
    args.reverse()
    spam = args.pop() if args else {}
    ham = args.pop() if args else []
    jam = args.pop() if args else open("jam.txt")

Suppose, instead, that Python had a syntax like this:

def foo(fixed_arg, spam=>{}, ham=>[], jam=>open("jam.txt")):
    """Foo the fixed_arg against the spam mapping, the
    ham sequence, and the jam file."""

The expressions would be evaluated as closures, using the same scope
that the function's own definition used. (This won't keep things alive
unnecessarily, as the function's body will be nested within that same
scope anyway.) Bikeshed the syntax all you like, but this would be
something to point people to: "here's how to get late-binding
semantics". For the purposes of documentation, the exact text of the
parameter definition could be retained, and like docstrings, they
could be discarded in -OO mode.

Would this satisfy the people who get confused about "=[]"?

ChrisA


From bc at freeuk.com  Thu Nov 19 14:48:55 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 19:48:55 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.479.1447960192.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
 <mailman.479.1447960192.16136.python-list@python.org>
Message-ID: <n2l8v7$7tq$1@dont-email.me>

On 19/11/2015 19:09, Chris Angelico wrote:
> On Fri, Nov 20, 2015 at 5:50 AM, BartC <bc at freeuk.com> wrote:
>> But you're not going to tell me what it is I got wrong!
>>
>> I said that Python's "=" does a very shallow copy. And I stated that in A=B,
>> something of B must be copied into A.
>>
>> I (and probably others) would like to know why none of that is correct. But
>> I suspect I'm not wrong.
>
> There's no copying happening. You evaluate the expression `B`, and get
> back some kind of object (because all expressions in Python evaluate
> to objects, unless they raise exceptions or in some way don't finish
> evaluating). The name A then becomes bound to that object. You're not
> copying a reference; you're simply referencing the result of an
> expression.

OK, so it's just a coincidence that after A=B, id(A) appears to be an 
identical copy of id(B)? And which also agrees with my assertions that a 
very shallow copy is done, and that some aspect of B is duplicated in A.

> It is an excellent explanation of the exact points you're confused about.

As far I'm concerned I'm not confused by these copying aspects. I said 
'very shallow copy', not 'shallow copy' nor 'deep copy' nor just 'copy'. 
To me, 'very shallow copy' about sums it up.

While Python byte-code for A=B:

     6 LOAD_GLOBAL              0 (b)
     9 STORE_GLOBAL             1 (a)

doesn't really disagree with me either as it looks remarkably like any 
other basic copy operation of any machine language or byte-code that has 
ever been invented.

If you said instead that I'm not using the official jargon then perhaps 
you're right. But the right terminology isn't going to make me like 
Python's default values any better!

-- 
Bartc


From rosuav at gmail.com  Thu Nov 19 14:58:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 06:58:42 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l8v7$7tq$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
 <mailman.479.1447960192.16136.python-list@python.org>
 <n2l8v7$7tq$1@dont-email.me>
Message-ID: <CAPTjJmrb6QmA+rMZAgs34wBQvMwHQxfs50ONB6np74kHaLyBVw@mail.gmail.com>

On Fri, Nov 20, 2015 at 6:48 AM, BartC <bc at freeuk.com> wrote:
> On 19/11/2015 19:09, Chris Angelico wrote:
>>
>> On Fri, Nov 20, 2015 at 5:50 AM, BartC <bc at freeuk.com> wrote:
>>>
>>> But you're not going to tell me what it is I got wrong!
>>>
>>> I said that Python's "=" does a very shallow copy. And I stated that in
>>> A=B,
>>> something of B must be copied into A.
>>>
>>> I (and probably others) would like to know why none of that is correct.
>>> But
>>> I suspect I'm not wrong.
>>
>>
>> There's no copying happening. You evaluate the expression `B`, and get
>> back some kind of object (because all expressions in Python evaluate
>> to objects, unless they raise exceptions or in some way don't finish
>> evaluating). The name A then becomes bound to that object. You're not
>> copying a reference; you're simply referencing the result of an
>> expression.
>
>
> OK, so it's just a coincidence that after A=B, id(A) appears to be an
> identical copy of id(B)? And which also agrees with my assertions that a
> very shallow copy is done, and that some aspect of B is duplicated in A.

When you execute A=B, you start by evaluating the expression B. It's
not a coincidence that re-evaluating a simple name immediately
afterward yields the same object:

>>> id(B)
140330420093056
>>> id(B)
140330420093056
>>> id(B)
140330420093056
>>> id(B)
140330420093056

But that's all you've proven. You've shown that the result of
evaluating B twice was the same object each time. That's no proof of
copying; it's just proof that, barring threading or other reentrancy
problems, expressions consisting solely of simple names are stable.

>> It is an excellent explanation of the exact points you're confused about.
>
>
> As far I'm concerned I'm not confused by these copying aspects. I said 'very
> shallow copy', not 'shallow copy' nor 'deep copy' nor just 'copy'. To me,
> 'very shallow copy' about sums it up.
>
> While Python byte-code for A=B:
>
>     6 LOAD_GLOBAL              0 (b)
>     9 STORE_GLOBAL             1 (a)

Technically that's CPython byte code. Python (the language) specifies
the semantics of assignment, but not the exact byte code used.

> doesn't really disagree with me either as it looks remarkably like any other
> basic copy operation of any machine language or byte-code that has ever been
> invented.

I think you're warping the word "copy" to mean what Python does on
assignment, rather than noting an actual similarity between Python
assignment and any other concept of copying. Remember, Python does not
have pointers, in the sense of machine integers storing addresses.
When you assign one C pointer variable to another, yes, you're copying
that integer value; but Python doesn't work that way, so there is
nothing to copy.

ChrisA


From lac at openend.se  Thu Nov 19 15:18:01 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 19 Nov 2015 21:18:01 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
Message-ID: <201511192018.tAJKI13E021560@fido.openend.se>

In a message of Fri, 20 Nov 2015 06:46:42 +1100, Chris Angelico writes:

>Would this satisfy the people who get confused about "=[]"?
>
>ChrisA

My experience says that the people who are confused want lists to
behave like tuples.  period.  i.e. they don't want lists to be 
mutable.  Which means when I say 'use a tuple instead' they go
away happy. Lots of very occasional programmers in my world (children)
just use tuples instead of lists and never get surprises and 
never go on to learn about lists and why they are a good idea.

But then there are those who come back with the problem:
'my python program is too slow'.  From a perspective of
'Let us understand why this is so and what could we do to make
things faster', I can get them to come up with the idea of a 
python list all on their own.  But this requires the sort of
brain that is interested in how interpreters work, otherwise
this conversation will not happen.

Without the actual problem biting them, the whole idea of
mutable objects seems, ah, hazardous.  I wonder if we do people
a disservice by introducing them straight off in teaching python
to absolute beginners, and if the learning would go easier if
we taught tuples and made them all use them a while before we
gave them lists.

At any rate, 'what is a mutable object' is a conversation that I 
have had too many times with people who really aren't interested.
I now think that 'use a tuple instead' is the way to go, with the
addition -- come back and talk to me about this at any time if you
want to learn why this is so.

Laura



From danielkasuza at gmail.com  Thu Nov 19 15:22:10 2015
From: danielkasuza at gmail.com (Daniel Kasuza)
Date: Thu, 19 Nov 2015 22:22:10 +0200
Subject: failing to run python on my pc
Message-ID: <CAGhiGqfU--Fu3rhj3iV43G5tmMAjGf_=UmFiOWyW5-0RuMusug@mail.gmail.com>

Dear Sir/Madam
I am student with University of the people and a beginner in programming.
My problem is that l have down loaded python 2.7 but l am failing to muse
it. If l try to to use it, I am getting an option which say run. If l press
run, it just run and come back to the same option. I want to use it for
some practice but i am failing.
Please help
Daniel


From ian.g.kelly at gmail.com  Thu Nov 19 15:37:54 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 13:37:54 -0700
Subject: Unsuccessful installation
In-Reply-To: <4530f633821e477798c80bf8d6d095f2@TSI-SV-MBX-01.tsi.corp.com>
References: <4530f633821e477798c80bf8d6d095f2@TSI-SV-MBX-01.tsi.corp.com>
Message-ID: <CALwzid=DH7rEErP6fL3wsKEJubvkKTkS3+Zj2AwB8q6ffZ5TJA@mail.gmail.com>

On Thu, Nov 19, 2015 at 12:45 PM, Kaufman, Stan <skaufman at tsi.com> wrote:
> Python would not run on this Windows XP computer.  After four  attempts at "change/remove" it still gives the same message:
>
> [cid:image001.png at 01D122D0.93CC3270]
>
> The first trip through "change/remove" appeared to be a further step in installation.  The second through fourth trips indicated "repairing..."  Each time, an attempt to run it resulted in the above message.

Python 3.5 does not support Windows XP. When Python 3.5.1 is released,
the installer will better communicate this.

You need to upgrade your OS to Vista or more recent, or downgrade your
Python to 3.4.


From marko at pacujo.net  Thu Nov 19 15:57:10 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 19 Nov 2015 22:57:10 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
Message-ID: <87d1v5emhl.fsf@elektro.pacujo.net>

Laura Creighton <lac at openend.se>:

> My experience says that the people who are confused want lists to
> behave like tuples. period. i.e. they don't want lists to be mutable.

I think it's simpler than that. When you have:

   def f(x=[]):
       y = []

the first [] is evaluated when "def" is executed, while the latter [] is
evaluated whenever "f" is executed. It's easy to be confused.


Marko


From bc at freeuk.com  Thu Nov 19 16:21:24 2015
From: bc at freeuk.com (BartC)
Date: Thu, 19 Nov 2015 21:21:24 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.480.1447960748.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
Message-ID: <n2leck$urt$1@dont-email.me>

On 19/11/2015 19:19, Chris Angelico wrote:
> On Fri, Nov 20, 2015 at 5:19 AM, BartC <bc at freeuk.com> wrote:

> But every choice has consequences. Steven gave you a few examples of
> the consequences of late-binding default arguments. For example, can
> you translate this into (one of) your language(s), and explain the
> semantics of the late binding?
>
> # scope 1: can be a module, an inner function, whatever
> y = 42
> def func(x=y):
>      return x
> def change_y():
>      global y # affect the one in this scope
>      y = 28
>
> # scope 2: another module/function/etc
> from scope1 import func # gain access, however that's done
>
> change_y()
> y = 7
> func()
>
>
> Should this return 7, 28, or 42?

I tried in two languages and both returned 28 the first time. Then I 
realised I'd missed out the y=7 line. Both then printed 7.

It doesn't matter so much if split across modules or not; it depends 
mainly on whether the y in 'y=7' is the same one in 'x=y' and 'y=28' and 
this depends on how it's declared or not and how.

(Both are here if you're interested: http://pastebin.com/0WPrYQw6)

Actually I'm just glad I got one of the results in your list!

(Python returns 42; so that means my languages are more dynamic than 
Python? That's hard to believe!)


  you don't need to look anywhere outside the
> function's own definition to grok its defaults. The default is stable
> (it won't change from one run to another - it'll always be the same
> object). Scope-recognizing late binding would use 28; it re-evaluates
> the expression 'y' in its original scope. This one makes the most
> sense to me, of all late-bind semantics; it also happens to be the
> same semantics as you get if you do the classic "if x is None: x=y"
> late-bind in Python, modulo the effect of the nested scope. But you're
> saying that it "simply substitute[s] the expression", which would mean
> that "func()" is exactly the same as "func(y)". A function default
> argument is therefore able to STEAL STUFF FROM THE CALLER'S SCOPE.
> Sorry for shouting, but if that ain't bizarre, I don't know what is.

Well, it's not quite the same as textual substitution of the default 
value expression, which would use names in the local scope at the call site.

The expression is evaluated using the entities in scope where the 
function is defined, as far as I can determine, although the byte-code 
that evaluates it is at the call site.

This is necessary I think because you want the default value to 
evaluated to the same result independently of the actual call site 
(unless the caller has deliberately manipulated things as in your example).

--


From w.g.sneddon at gmail.com  Thu Nov 19 16:53:09 2015
From: w.g.sneddon at gmail.com (bSneddon)
Date: Thu, 19 Nov 2015 13:53:09 -0800 (PST)
Subject: Dabbling in web development
Message-ID: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>

I know there are a plethora of web frameworks out there for Python and to be serious about website developement I should learn on like Django.   Really thought, I just want to dabble and do some easy stuff.   Does anyone have any suggestons?   I have a a website hosted with a hosting company who is supposed to have python support but hard to know what they have installed on there apache server.   I have seen a few examples out there but not too many.  


From ian.g.kelly at gmail.com  Thu Nov 19 17:03:47 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 15:03:47 -0700
Subject: Dabbling in web development
In-Reply-To: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
Message-ID: <CALwzid=0=GWWaVuQJwqNFZVQTxewHf9n0AtWKZ5GuqcXQjXyTg@mail.gmail.com>

On Thu, Nov 19, 2015 at 2:53 PM, bSneddon <w.g.sneddon at gmail.com> wrote:
> I know there are a plethora of web frameworks out there for Python and to be serious about website developement I should learn on like Django.   Really thought, I just want to dabble and do some easy stuff.   Does anyone have any suggestons?   I have a a website hosted with a hosting company who is supposed to have python support but hard to know what they have installed on there apache server.   I have seen a few examples out there but not too many.

Flask is a good choice if you're just looking for something easy to get going.


From breamoreboy at yahoo.co.uk  Thu Nov 19 17:35:37 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 19 Nov 2015 22:35:37 +0000
Subject: Dabbling in web development
In-Reply-To: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
Message-ID: <n2lisc$atq$1@ger.gmane.org>

On 19/11/2015 21:53, bSneddon wrote:
> I know there are a plethora of web frameworks out there for Python and to be serious about website developement I should learn on like Django.   Really thought, I just want to dabble and do some easy stuff.   Does anyone have any suggestons?   I have a a website hosted with a hosting company who is supposed to have python support but hard to know what they have installed on there apache server.   I have seen a few examples out there but not too many.
>

Take a look at "Popular Non Full-Stack Frameworks" here 
https://wiki.python.org/moin/WebFrameworks

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From lac at openend.se  Thu Nov 19 17:41:19 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 19 Nov 2015 23:41:19 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87d1v5emhl.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
Message-ID: <201511192241.tAJMfJZ6031048@fido.openend.se>

In a message of Thu, 19 Nov 2015 22:57:10 +0200, Marko Rauhamaa writes:
>Laura Creighton <lac at openend.se>:
>
>> My experience says that the people who are confused want lists to
>> behave like tuples. period. i.e. they don't want lists to be mutable.
>
>I think it's simpler than that. When you have:
>
>   def f(x=[]):
>       y = []
>
>the first [] is evaluated when "def" is executed, while the latter [] is
>evaluated whenever "f" is executed. It's easy to be confused.
>
>
>Marko

Note: Ned Bachelder (who is probably reading this on python-list
anyway added cc on this mail, as if I am to discuss somebody, however
briefly, they deserve to hear about it.  Which may irritate him to
get 2 copies instead of one, but so it goes.  I am talking about
BartC as well, but since this is his thread, I assume he is here.)

Now back to what Marko said:

This is one of the times when it is nice to be dealing with children.
The whole notion of 'when def is executed' is not on their radar
at all.  It is all a matter of 'I write this, I want that'. :)

And with reasonable amount of authority from experience, I can
tell you that 'write it with round brackets not square ones'
makes the code *just work* for a large number of students who
only have a limited amount of patience for 'understanding 
what they are doing'.  They want to be able to do it first,
and have understanding come later (if at all).

This is the learning approach of 'training' as opposed to
'educating'.  And, for all that we _talk_ of 'educating our
children' -- what we really do, a whole lot of the time, is
train them.  The very basic skills of reading, writing (typing?) 
and arithmetic and foreign languages  need to be trained, and no
amount of understanding the theory behind such things will
ever directly translate into being able to do it.

Indeed, the best authority on the planet on 13th century French court
dances is a one-legged Frenchman, (whose name I now forget).
Although he has (or maybe had, he is likely dead by now, he lost
his leg in WW2) the education and the theory and the scholasticism, 
anybody with 2 legs, however ignorant, can dance the court dances
better. 

Sometimes you want to understand what you are doing.  Sometimes
you just want to do it.  And sometimes, well, the only real way 
to get an understanding of what you are doing is to do it more.
This is, in my opinion, Bartc's problem. He doesn't program in
python enough to understand it more.  He wants us to give him
a better theoretical understanding of Python, but for me, at 
any rate he is hitting the wrong audience.  And Ned Batchelder
is unlikely to help.  Both of us come from the practical end
of things, and write lessons and talks like the one ChrisA
recommended -- which is wonderful.  And how I wish I could 
write like that -- but they are aimed at telling a practical
python programmer 'now that you know how to do it, here is how
to understand what you do'.  And then, pedagogically, you can 
move to 'and now you understand what you have been doing, here
are some awesome cool tricks you can do to make your life easier
(and impress your friends, for a particularly nerdy set of
freinds).

I don't think that Ned works for the untrained python programmer.
And until Bart writes a bunch of code in python, for many weeks
or even months, I will not be able to help him, either.

But in my life, I end up teaching programming, often to some very
smart young people who are specialists at being trained. They want me
to train them, not educate them.  When you are 9 years old,
approaching all of life with the attitude of 'how do I get <anything>
to spit out the results I want' is enormously adaptive.

They have the opposite problem of BartC -- they want to be excellent
programmers without understanding anything, while he wants to 
understand everything before he knows how to write decent python code.

It's a pedagogical problem.

Laura


From lac at openend.se  Thu Nov 19 17:53:44 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 19 Nov 2015 23:53:44 +0100
Subject: Dabbling in web development
In-Reply-To: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
Message-ID: <201511192253.tAJMrinN031922@fido.openend.se>

In a message of Thu, 19 Nov 2015 13:53:09 -0800, bSneddon writes:

>I know there are a plethora of web frameworks out there for Python
 and to be serious about website developement I should learn on like
 Django.  Really thought, I just want to dabble and do some easy
 stuff.  Does anyone have any suggestons?  I have a a website hosted
 with a hosting company who is supposed to have python support but
 hard to know what they have installed on there apache server.  I have
 seen a few examples out there but not too many.

There are lots of other choices than Django.  

see: https://wiki.python.org/moin/WebFrameworks/

The big split is whether you want a large framework, like Django, which
comes with all the batteries included, or a micro framework, like
Flask and Bottle, which gives you more control and is a whole lot
simpler.  

It is not the case that 'serious website developers use heavyweight
systems like Django' --- lots and lots of serious developers use 
Flask or Bottle because Django makes you do it the Django way.
Flask lets you do it however you like.  Professionally, our company
has designed a ton of websites and we use Flask nearly all of the
time, and Pylons the rest of the time.  If your brain is well-suited
for Django, by all means use that, but if it is not, then do something 
else.

I teach kids who are 9-12 years old, weekends.
Hosting their own site to support pictures of their pets is a very
common thing to want to do.

I have translated this:
http://bottlepy.org/docs/dev/tutorial.html

into Swedish and we tend to get a website up and running in 3 weekends
of thinking and coding.  (This is with kids who already know Python.
Learning enough python to do this takes longer, a whole lot longer
if you only get to code on weekends -- but most of the kids who want
to do this are also willing to write code on weekdays as well.)

Laura


From torriem at gmail.com  Thu Nov 19 17:55:50 2015
From: torriem at gmail.com (Michael Torrie)
Date: Thu, 19 Nov 2015 15:55:50 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <n2leck$urt$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
Message-ID: <564E5376.1000807@gmail.com>

On 11/19/2015 02:21 PM, BartC wrote:
> (Python returns 42; so that means my languages are more dynamic than 
> Python? That's hard to believe!)

It tells me your language does late binding for default arguments, which
does mean the default argument can dynamically change at call time,
which would surprise me if I didn't know about it.  Either form of
binding is acceptable, and I don't think it makes a language more or
less dynamic.  Of course as Chris and Laura have said, a list as a
default parameter throws people off because of the semantics of
mutability, and the fact that Python's variable model does not follow
the traditional memory box model used in compiled languages like C.



From lac at openend.se  Thu Nov 19 18:00:24 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 20 Nov 2015 00:00:24 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?) (fwd)
Message-ID: <201511192300.tAJN0OnW032461@fido.openend.se>

Arrgh!

I got Ned Batchelder's email wrong.  Forgot the t.
(for somebody whose irc nick is nedbat.  )

sending this to him again.   warning any repliers that the
mail address is wrong....

apologies,
Laura


------- Forwarded Message

From: Laura Creighton <lac at openend.se>
Subject: Re: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-reply-to: <87d1v5emhl.fsf at elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg at mail.gmail.com

In a message of Thu, 19 Nov 2015 22:57:10 +0200, Marko Rauhamaa writes:
>Laura Creighton <lac at openend.se>:
>
>> My experience says that the people who are confused want lists to
>> behave like tuples. period. i.e. they don't want lists to be mutable.
>
>I think it's simpler than that. When you have:
>
>   def f(x=[]):
>       y = []
>
>the first [] is evaluated when "def" is executed, while the latter [] is
>evaluated whenever "f" is executed. It's easy to be confused.
>
>
>Marko

Note: Ned Bachelder (who is probably reading this on python-list
anyway added cc on this mail, as if I am to discuss somebody, however
briefly, they deserve to hear about it.  Which may irritate him to
get 2 copies instead of one, but so it goes.  I am talking about
BartC as well, but since this is his thread, I assume he is here.)

Now back to what Marko said:

This is one of the times when it is nice to be dealing with children.
The whole notion of 'when def is executed' is not on their radar
at all.  It is all a matter of 'I write this, I want that'. :)

And with reasonable amount of authority from experience, I can
tell you that 'write it with round brackets not square ones'
makes the code *just work* for a large number of students who
only have a limited amount of patience for 'understanding 
what they are doing'.  They want to be able to do it first,
and have understanding come later (if at all).

This is the learning approach of 'training' as opposed to
'educating'.  And, for all that we _talk_ of 'educating our
children' -- what we really do, a whole lot of the time, is
train them.  The very basic skills of reading, writing (typing?) 
and arithmetic and foreign languages  need to be trained, and no
amount of understanding the theory behind such things will
ever directly translate into being able to do it.

Indeed, the best authority on the planet on 13th century French court
dances is a one-legged Frenchman, (whose name I now forget).
Although he has (or maybe had, he is likely dead by now, he lost
his leg in WW2) the education and the theory and the scholasticism, 
anybody with 2 legs, however ignorant, can dance the court dances
better. 

Sometimes you want to understand what you are doing.  Sometimes
you just want to do it.  And sometimes, well, the only real way 
to get an understanding of what you are doing is to do it more.
This is, in my opinion, Bartc's problem. He doesn't program in
python enough to understand it more.  He wants us to give him
a better theoretical understanding of Python, but for me, at 
any rate he is hitting the wrong audience.  And Ned Batchelder
is unlikely to help.  Both of us come from the practical end
of things, and write lessons and talks like the one ChrisA
recommended -- which is wonderful.  And how I wish I could 
write like that -- but they are aimed at telling a practical
python programmer 'now that you know how to do it, here is how
to understand what you do'.  And then, pedagogically, you can 
move to 'and now you understand what you have been doing, here
are some awesome cool tricks you can do to make your life easier
(and impress your friends, for a particularly nerdy set of
freinds).

I don't think that Ned works for the untrained python programmer.
And until Bart writes a bunch of code in python, for many weeks
or even months, I will not be able to help him, either.

But in my life, I end up teaching programming, often to some very
smart young people who are specialists at being trained. They want me
to train them, not educate them.  When you are 9 years old,
approaching all of life with the attitude of 'how do I get <anything>
to spit out the results I want' is enormously adaptive.

They have the opposite problem of BartC -- they want to be excellent
programmers without understanding anything, while he wants to 
understand everything before he knows how to write decent python code.

It's a pedagogical problem.

Laura
- -- 
https://mail.python.org/mailman/listinfo/python-list

------- End of Forwarded Message


From maillist at schwertberger.de  Thu Nov 19 18:02:53 2015
From: maillist at schwertberger.de (Dietmar Schwertberger)
Date: Fri, 20 Nov 2015 00:02:53 +0100
Subject: Dabbling in web development
In-Reply-To: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
Message-ID: <564E551D.8070704@schwertberger.de>

Am 19.11.2015 um 22:53 schrieb bSneddon:
> I know there are a plethora of web frameworks out there for Python and to be serious about website developement I should learn on like Django.   Really thought, I just want to dabble and do some easy stuff.   Does anyone have any suggestons?   I have a a website hosted with a hosting company who is supposed to have python support but hard to know what they have installed on there apache server.   I have seen a few examples out there but not too many.
Maybe, you should have a look at the book "Lightweight Django".

Regards,

Dietmar


From marko at pacujo.net  Thu Nov 19 18:07:24 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 20 Nov 2015 01:07:24 +0200
Subject: Dabbling in web development
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
 <mailman.494.1447973633.16136.python-list@python.org>
Message-ID: <8737w1eggj.fsf@elektro.pacujo.net>

Laura Creighton <lac at openend.se>:

> There are lots of other choices than Django.  
>
> see: https://wiki.python.org/moin/WebFrameworks/

However, are there any good web applications? I have seen some heroic
attempts but most fail miserably or at least have some annoying
glitches.

The cardinal sin of web development seems to be micromanagement. Instead
of letting the web standards do their work, the application wants to be
in full control with JavaScript and XML HTTP requests. The results can
be awe-inspiring but at the same time fail at the basics. For example,
select/copy with the mouse might not work. Fonts might be garbled. Half
the page might be invisible and unscrollable. Or nothing will be
displayed at all.


Marko


From rosuav at gmail.com  Thu Nov 19 18:09:01 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 20 Nov 2015 10:09:01 +1100
Subject: Dabbling in web development
In-Reply-To: <201511192253.tAJMrinN031922@fido.openend.se>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
 <201511192253.tAJMrinN031922@fido.openend.se>
Message-ID: <CAPTjJmrYTX-3aM-UCzFub5VB5=OQt8HNLjwZsiTgB8ttTJvynw@mail.gmail.com>

On Fri, Nov 20, 2015 at 9:53 AM, Laura Creighton <lac at openend.se> wrote:
> It is not the case that 'serious website developers use heavyweight
> systems like Django' --- lots and lots of serious developers use
> Flask or Bottle because Django makes you do it the Django way.
> Flask lets you do it however you like.  Professionally, our company
> has designed a ton of websites and we use Flask nearly all of the
> time, and Pylons the rest of the time.  If your brain is well-suited
> for Django, by all means use that, but if it is not, then do something
> else.
>
> I teach kids who are 9-12 years old, weekends.
> Hosting their own site to support pictures of their pets is a very
> common thing to want to do.

To add to the Flask recommendation: I teach adults (mostly; one of my
students is in high school) to use Python, SQLAlchemy, and Flask,
putting together a classic dynamic web site model. (I also use Flask
myself for a couple of sites, and I like it; but that recommendation
is weak because I don't have much experience with *other* frameworks.
So all it means is "Flask hasn't majorly annoyed me".)

ChrisA


From lac at openend.se  Thu Nov 19 18:20:09 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 20 Nov 2015 00:20:09 +0100
Subject: Dabbling in web development
In-Reply-To: <CAPTjJmrYTX-3aM-UCzFub5VB5=OQt8HNLjwZsiTgB8ttTJvynw@mail.gmail.com>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
 <201511192253.tAJMrinN031922@fido.openend.se>
 <CAPTjJmrYTX-3aM-UCzFub5VB5=OQt8HNLjwZsiTgB8ttTJvynw@mail.gmail.com>
Message-ID: <201511192320.tAJNK92a001507@fido.openend.se>

In a message of Fri, 20 Nov 2015 10:09:01 +1100, Chris Angelico writes:
>On Fri, Nov 20, 2015 at 9:53 AM, Laura Creighton <lac at openend.se> wrote:
>> It is not the case that 'serious website developers use heavyweight
>> systems like Django' --- lots and lots of serious developers use
>> Flask or Bottle because Django makes you do it the Django way.
>> Flask lets you do it however you like.  Professionally, our company
>> has designed a ton of websites and we use Flask nearly all of the
>> time, and Pylons the rest of the time.  If your brain is well-suited
>> for Django, by all means use that, but if it is not, then do something
>> else.
>>
>> I teach kids who are 9-12 years old, weekends.
>> Hosting their own site to support pictures of their pets is a very
>> common thing to want to do.
>
>To add to the Flask recommendation: I teach adults (mostly; one of my
>students is in high school) to use Python, SQLAlchemy, and Flask,
>putting together a classic dynamic web site model. (I also use Flask
>myself for a couple of sites, and I like it; but that recommendation
>is weak because I don't have much experience with *other* frameworks.
>So all it means is "Flask hasn't majorly annoyed me".)
>
>ChrisA

Well, I highly recommend Flask, but the tutorial was for a
different microframework, 'Bottle'.

At the time I first collected the kids, it was a better tutorial.
Now, I suspect, there are lots of great ones for both of them.
But for me, the effort of translating any tutorial into Swedish
is huge.  Especially since I need to take a reputation hit with
every Swedish grammatical error my students find.  :)  The
students of 3 years ago have fixed my Swedish problems, mostly,
I think by now in this tutorial.

Being able to speak Swedish colloquially and read it does not 
mean you can write or translate it well enough to get your product
past the hyper-critical eyes of 11-year-olds who want evidence 
that this teacher, unlike so many others, can deliver the promised
goods. :)

Laura


From lac at openend.se  Thu Nov 19 18:28:30 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 20 Nov 2015 00:28:30 +0100
Subject: Dabbling in web development
In-Reply-To: <8737w1eggj.fsf@elektro.pacujo.net>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
 <mailman.494.1447973633.16136.python-list@python.org>
 <8737w1eggj.fsf@elektro.pacujo.net>
Message-ID: <201511192328.tAJNSUjK002147@fido.openend.se>

In a message of Fri, 20 Nov 2015 01:07:24 +0200, Marko Rauhamaa writes:
>Laura Creighton <lac at openend.se>:
>
>> There are lots of other choices than Django.  
>>
>> see: https://wiki.python.org/moin/WebFrameworks/
>
>However, are there any good web applications? I have seen some heroic
>attempts but most fail miserably or at least have some annoying
>glitches.
>
>The cardinal sin of web development seems to be micromanagement. Instead
>of letting the web standards do their work, the application wants to be
>in full control with JavaScript and XML HTTP requests. The results can
>be awe-inspiring but at the same time fail at the basics. For example,
>select/copy with the mouse might not work. Fonts might be garbled. Half
>the page might be invisible and unscrollable. Or nothing will be
>displayed at all.
>
>
>Marko

But you see that whether or not you use a Heavy framework like
Django or a Microframework like Flask (which is all about how
to serve such things up .... how you butcher the results is
your own business.)

Web design is a lot harder than most people who make webpages think.

So what else is new?

Laura


From bc at freeuk.com  Thu Nov 19 19:11:25 2015
From: bc at freeuk.com (BartC)
Date: Fri, 20 Nov 2015 00:11:25 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.495.1447973754.16136.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
Message-ID: <n2lobe$7gs$1@dont-email.me>

On 19/11/2015 22:55, Michael Torrie wrote:
> On 11/19/2015 02:21 PM, BartC wrote:
>> (Python returns 42; so that means my languages are more dynamic than
>> Python? That's hard to believe!)
>
> It tells me your language does late binding for default arguments, which
> does mean the default argument can dynamically change at call time,
> which would surprise me if I didn't know about it.  Either form of
> binding is acceptable, and I don't think it makes a language more or
> less dynamic.

You get the expression that is specified, which can give different 
values at different times unless it involves only constants.

It can't be exactly the same as writing an identical expression in place 
of the missing argument, as apparently different scopes come into play 
if names are involved.

However I mainly use them for constant values. And [] is a constant 
value in my opinion.

-- 
Bartc


From steve at pearwood.info  Thu Nov 19 19:26:54 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 20 Nov 2015 11:26:54 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
Message-ID: <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 05:50 am, BartC wrote:


> I said that Python's "=" does a very shallow copy. And I stated that in
> A=B, something of B must be copied into A.
> 
> I (and probably others) would like to know why none of that is correct.
> But I suspect I'm not wrong.

Nothing of B is copied.

Here is a terrible ASCII art diagram of an object, floating in memory (most
likely in the heap), an instant before the garbage collector can reach it
and collect it:

               +----------------------+
               |  DEADBEEF0012345...  |
               +----------------------+

(Best viewed in a monospaced font, like Courier.)

The contents of the object are shown as a hex-dump, and will depend on the
actual object and its value, but in general you would expect a field which
acts as some sort of tag or pointer linking the instance to its parent
class, plus other fields specifying the object's value and/or attributes.
The internal details of the object don't matter, but basically objects are
structs or records.

Here is an ASCII art diagram of that same object, now bound to the name "B",
preventing the GC from collecting it:

               +----------------------+
B------------->|  DEADBEEF0012345...  |
               +----------------------+

The name "B" may be on the heap, or in an array. It is possible that the
human-readable string "B" itself no longer appears in memory. I don't care
about the specific implementation, but for the record, in the case of
CPython the name "B" is itself a string object in the heap, linked to from
a specific associative array (hash table) also in the heap. (I think.)

The link between the name B and the object ---> could be anything that
allows the compiler/interpreter to associate one to the other. We call it
a "reference". In CPython, references are pointers. If somebody were to
write Python using FORTRAN 77, they would most likely use a big array to
hold the objects, and use the index into the array as references. Other
implementations may use other things, but for simplicity, let's just stick
with calling it a pointer.

Now let's do the assignment A = B:

               +----------------------+
B------------->|  DEADBEEF0012345...  |
            +->+----------------------+
            |
A-----------+

This adds a new reference (think: pointer) to the object, linked to the
name "A". But **nothing of the object** is copied. The pointers to the
object are not part of the object -- they are external to the object.

If you want to talk about anything being copied, you should talk about
*copying the reference* to B, not copying B.

[Aside: there is some ambiguity here. If I say "a reference to B", I
actually mean a reference to the object referenced to by B. I don't mean a
reference to the *name* B. Python doesn't support that feature: names are
not values in Python.]



-- 
Steven



From ned at nedbatchelder.com  Thu Nov 19 19:27:57 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 19 Nov 2015 16:27:57 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <n2lobe$7gs$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
Message-ID: <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>

On Thursday, November 19, 2015 at 7:11:52 PM UTC-5, BartC wrote:
> On 19/11/2015 22:55, Michael Torrie wrote:
> > On 11/19/2015 02:21 PM, BartC wrote:
> >> (Python returns 42; so that means my languages are more dynamic than
> >> Python? That's hard to believe!)
> >
> > It tells me your language does late binding for default arguments, which
> > does mean the default argument can dynamically change at call time,
> > which would surprise me if I didn't know about it.  Either form of
> > binding is acceptable, and I don't think it makes a language more or
> > less dynamic.
> 
> You get the expression that is specified, which can give different 
> values at different times unless it involves only constants.
> 
> It can't be exactly the same as writing an identical expression in place 
> of the missing argument, as apparently different scopes come into play 
> if names are involved.
> 
> However I mainly use them for constant values. And [] is a constant 
> value in my opinion.
> 
> -- 
> Bartc

You are not alone in being surprised by how mutable default values work.
It is a topic that comes up in every "What's Bad About Python" discussion,
and is a common question from new users of the language.

I can understand how you would view [] as a constant value.  It's true that
it is an expression that produces a consistent value each time it is
evaluated.  But that value is a list, and lists are mutable.  The examples
here all use the .append() method on that value, which changes it.

Different languages work differently.  In Python, a default value expression
for a function argument is evaluated only once, when the function is defined.
That value (in this case, the actual list) is stored with the function. The
expression is not stored, the value of the expression is. That value (the
actual list) is supplied as the value of the argument if no other value is
supplied.  If you modify that value in the function, the value is modified,
and used again at the next function call.

Again, we understand why you are surprised by this, many people are. You'll
have to accept it, it's just the way Python works.  There have been many
discussions about alternatives, and they are considered to be either too
complicated, or have other undesirable behavior, or both.

--Ned.


From steve at pearwood.info  Thu Nov 19 19:33:36 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 20 Nov 2015 11:33:36 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
Message-ID: <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 07:57 am, Marko Rauhamaa wrote:

> Laura Creighton <lac at openend.se>:
> 
>> My experience says that the people who are confused want lists to
>> behave like tuples. period. i.e. they don't want lists to be mutable.
> 
> I think it's simpler than that. When you have:
> 
>    def f(x=[]):
>        y = []
> 
> the first [] is evaluated when "def" is executed, while the latter [] is
> evaluated whenever "f" is executed. It's easy to be confused.

It shouldn't be. The function declaration 

    def f(x=[]):

is executed only once. The function body, conveniently indented to make it
stand out:

        y = []

is executed every time you call the function. 


[Aside: that nice clean design is somewhat muddied by docstrings. Despite
being indented, docstrings are actually part of the declaration in the
sense that they are handled only once, at function definition time.]


-- 
Steven



From ned at nedbatchelder.com  Thu Nov 19 19:36:17 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Thu, 19 Nov 2015 16:36:17 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
 <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <f1dc4b01-77e7-4df4-b416-609adb21b772@googlegroups.com>

On Thursday, November 19, 2015 at 7:28:44 PM UTC-5, Steven D'Aprano wrote:
> On Fri, 20 Nov 2015 05:50 am, BartC wrote:
> 
> 
> > I said that Python's "=" does a very shallow copy. And I stated that in
> > A=B, something of B must be copied into A.
> > 
> > I (and probably others) would like to know why none of that is correct.
> > But I suspect I'm not wrong.
> 
> Nothing of B is copied.

I think we are stuck in a simple terminology conflict here.  There is something
of B copied.  The name B refers to a value.  In CPython, that reference is a
pointer.  That pointer (the memory address) is copied from B to A.

Nothing of "B's value", that is, the object B is referring to, is copied. But
there is something about B (the pointer to its value) that is now also something
about A, because A also has that pointer.

--Ned.


From ian.g.kelly at gmail.com  Thu Nov 19 19:59:48 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Thu, 19 Nov 2015 17:59:48 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
 <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CALwzid=uwrL=xwd1+To7Wu-vb-8g2wTp8Gfq9kAEhbatLDRc3g@mail.gmail.com>

On Nov 19, 2015 5:31 PM, "Steven D'Aprano" <steve at pearwood.info> wrote:
>
> [Aside: there is some ambiguity here. If I say "a reference to B", I
> actually mean a reference to the object referenced to by B. I don't mean a
> reference to the *name* B. Python doesn't support that feature: names are
> not values in Python.]

Quoting BartC:

"""
if you write A=B then something of B needs to have been copied into A, even
if it's just the reference that B contains. Otherwise it would be difficult
to get A to refer to the same object as B.
"""

If you're trying to draw some distinction between what BartC wrote 17 posts
back and what you wrote here, I'm not seeing it.


From lac at openend.se  Thu Nov 19 20:00:02 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 20 Nov 2015 02:00:02 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <f1dc4b01-77e7-4df4-b416-609adb21b772@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.476.1447957612.16136.python-list@python.org>
 <n2l5h7$p1u$1@dont-email.me>
 <564e68d0$0$1608$c3e8da3$5496439d@news.astraweb.com>
 <f1dc4b01-77e7-4df4-b416-609adb21b772@googlegroups.com>
Message-ID: <201511200100.tAK102lc008293@fido.openend.se>

In a message of Thu, 19 Nov 2015 16:36:17 -0800, Ned Batchelder writes:
>On Thursday, November 19, 2015 at 7:28:44 PM UTC-5, Steven D'Aprano wrote:
>> On Fri, 20 Nov 2015 05:50 am, BartC wrote:
>> 
>> 
>> > I said that Python's "=" does a very shallow copy. And I stated that in
>> > A=B, something of B must be copied into A.
>> > 
>> > I (and probably others) would like to know why none of that is correct.
>> > But I suspect I'm not wrong.
>> 
>> Nothing of B is copied.
>
>I think we are stuck in a simple terminology conflict here.  There is something
>of B copied.  The name B refers to a value.  In CPython, that reference is a
>pointer.  That pointer (the memory address) is copied from B to A.
>
>Nothing of "B's value", that is, the object B is referring to, is copied. But
>there is something about B (the pointer to its value) that is now also something
>about A, because A also has that pointer.
>
>--Ned.

In PyPy we do this too.
But we don't copy a memory-address pointer.
We have a moving garbage collector, and no objects are in any way
guaranteed to be at their last memory address.

We copy a thing that, when you ask it nicely, spits out "where the hell
is the object right now,  because I want to modify it."

But this thing is in no way tied to any particular place in any DRAM.
It hits PyPy at an abstraction layer above that of 'we write 1s and 0s
here' so if you want to implement python on a message passing system
implemented by carrier pigeon, we could do this.  It would be slow,
however. :)

Laura


From steve at pearwood.info  Thu Nov 19 20:05:55 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 20 Nov 2015 12:05:55 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
Message-ID: <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 04:30 am, BartC wrote:

> On 19/11/2015 16:01, Steven D'Aprano wrote:
[...]

> The whole concept of 'mutable' default is alien to me. A default is just 
> a convenient device to avoid having to write:
> 
>    fn(0) or fn("") or fn([])

Says who?

Here's another use for function defaults, as static storage:


# Ackermann's function
def ack(m, n, _memo={}):
    key = m, n
    if key not in _memo:
        if m==0: v = n + 1
        elif n==0: v = ack(m-1, 1)
        else: v = ack(m-1, ack(m, n-1))
        _memo[key] = v
    return _memo[key]


This is a quick and easy way to memoise a function which would otherwise be
horribly slow. And it only works because _memo is bound to a mutable object
once, and once only.

 
> You just write fn() instead. But it shouldn't come at the cost of
> completely different semantics! Because then it can't really be called a
> default value at all.

But it doesn't come with completely different semantics. This is the stock
standard semantics for assignment.

Since we're not passing an argument, let's get rid of the argument
altogether. If we put the assignment inside the body of the function, that
code is executed every time the function is called. "arg" gets a brand new,
empty list each time:

def test():
    arg = []
    arg.append(1)
    return len(arg)


If we put the assignment *outside* of the body of the function, that code is
executed once only, and the same list is used over and over again:

arg = []
def test():
    arg.append(1)
    return len(arg)



This is *exactly* the same semantics as for parameter defaults (except that
they aren't stored as globals, but as hidden fields deep inside the
function object itself). Now, look at the function declaration:


def test(arg=[]):
    arg.append(1)
    return len(arg)


The binding arg=[] is NOT inside the body of the function. Therefore, it is
NOT executed repeatedly, but only once.


>   isn't surprising to
>> somebody coming from a completely different paradigm. I was surprised by
>> it too, the first time I got bitten.
> 
> So you didn't bother reading the LRM either!

LRM? Left Right Manual?

No, I read it. I knew that the list was only created once. But like I said,
I didn't follow the implications of that. If it is only created once, and
you modify the value, the value will be modified.


>> py> def demo_const(x, y=[]):
>> ...     return x + len(y)
> 
>> Exactly as you should expect. Where you run into trouble is when the
>> default value is NOT a constant:
>>
>> py> def demo_variable(x, y=[]):
>> ...     y.append(1)
>> ...     return x + len(y)
> 
> Sorry, what is the default value in each of these? As the first lines of
> the defintions look identical apart from the function names.

The *value* is whatever contents the list holds.

a = []
a.append(1)
a.append(2)
a.append(3)

What's the value of a? Are you shocked and horrified to discover that the
value of a is not the empty list, but the list [1, 2, 3]?



>> py> demo_variable(5)
>> 6
>> py> demo_variable(5)
>> 7
>> py> demo_variable(5)
>> 8
>>
>>
>> If you modify the value, the value will be modified. Why are you
>> surprised by this?
> 
> Which value is being modified? The []?

The object bound to y is being modified. y.append(1) modifies the object
bound to y. That object gets taken from the defaults if you don't supply a
value yourself. That default object starts of life as an empty list, but it
doesn't stay empty if you append to it.



>>>> When you deal with mutable objects, you have to expect them to mutate.
>>>> The whole point of mutability is that their value can change.
>>>
>>> That [] doesn't look like an object that could change.
>>
>> Of course it does.
> 
> You've lost me know.
> 
> Are you saying that:
> 
>    a=[]
> 
> why sometimes not assign an empty list, because that [] could have been
> modified?

No. But [] is syntax for an empty list, and lists can change -- they are
mutable.

a = []
a.append(1)

Are you shocked to learn that a is no longer an empty list? (I know I asked
a similar question before, but this is an important point.)


>> It is a list literal, like int literals, float literals,
>> string literals and the rest.
> 
> Another surprise? Literals by definition can't change:

Says who? The existence of literal syntax is a feature of the programming
language. The mutability of values is a *separate* feature. The two are
unrelated.


> def fn():
> a=[10,20,30]
> a.append(999)
> 
> I would hope that a is set to [10,20,30] at each entry to the function!

Naturally. Each time you call the function, the body of the function
executes and creates a new list. You take that list, and then modify it in
the very next line with a.append(999).

What happens if you only create the list *once*?

a = [10,20,30]
def fn():
    a.append(999)
    print(a)


Are you surprised that a doesn't get reset to [10, 20, 30] each time you
call the function?


>> Assignments are not copies at all.
> 
> if you write A=B then something of B needs to have been copied into A,
> even if it's just the reference that B contains. Otherwise it would be
> difficult to get A to refer to the same object as B.

B doesn't contain the reference to itself. The reference is external to B.
Nothing of B is copied.



-- 
Steven



From wrw at mac.com  Thu Nov 19 21:58:27 2015
From: wrw at mac.com (William Ray Wing)
Date: Thu, 19 Nov 2015 21:58:27 -0500
Subject: Writing a Financial Services App in Python
In-Reply-To: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
References: <6f4f4d39-d33b-46dd-bda7-afeb2f0dbef4@googlegroups.com>
Message-ID: <60000857-0F97-4FF0-B093-DB3DDF7B0973@mac.com>


> On Nov 19, 2015, at 6:59 AM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> 
> 
> From YCombinator's new RFS, This is the problem I want to solve as it is a severe problem I face myself and something I need. I want to write this app in Python as I heard that Python is a great language that many programmers use ... How / where do I start ? The problem is detailed below :
> 
> FINANCIAL SERVICES
> 

[Big edit]

You might enjoy reading the note here:  http://www.wsj.com/articles/an-algo-and-a-dream-for-day-traders-1439160100?mod=djem10point

Which, among other things, points out that DIY algorithmic trading is the latest DIY craze.

Bill




From mscir at yahoo.com  Thu Nov 19 22:09:03 2015
From: mscir at yahoo.com (Mike S)
Date: Thu, 19 Nov 2015 19:09:03 -0800
Subject: how do I learn python ?
In-Reply-To: <mailman.451.1447923718.16136.python-list@python.org>
References: <BLU177-W25FC22D76121842F28AC97871C0@phx.gbl>
 <mailman.451.1447923718.16136.python-list@python.org>
Message-ID: <n2m2o5$see$1@dont-email.me>

On 11/19/2015 1:00 AM, Michiel Overtoom wrote:
>
>> On 18 Nov 2015, at 05:58, ??? <hua_lin at live.cn> wrote:
>> (nothing)
>
> You might want to start at https://www.python.org/about/gettingstarted/
>
> PS. Leaving the body of an email or usenet article empty is considered bad form.
>
> Greetings,

Thanks for that, there is a great list of tutorials there!
https://wiki.python.org/moin/BeginnersGuide/Programmers



From mscir at yahoo.com  Thu Nov 19 22:26:49 2015
From: mscir at yahoo.com (Mike S)
Date: Thu, 19 Nov 2015 19:26:49 -0800
Subject: Why won't this run?
In-Reply-To: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
References: <ea4e1c5e-08e8-4a75-95ce-9e4eeca92021@googlegroups.com>
Message-ID: <n2m3pf$vod$1@dont-email.me>

On 11/15/2015 12:38 PM, jbak36 wrote:
> Python 3.5.0 (v3.5.0:374f501f4567, Sep 13 2015, 02:27:37) [MSC v.1900 64 bit (AMD64)] on win32
> Type "copyright", "credits" or "license()" for more information.
>>>> #this program says hello and asks for my name
>>>> print:('Hello world!')
> Hello world!
>>>> print:('What is your name?') #ask for their name
> What is your name?
>>>> myName = input()
> print:('It is good to meet you,'+myName)
>>>> print:('The length of your name is:')
> The length of your name is:
>>>> print:(len(myName))
> 39
>>>> print:('What is your age?')#ask for their age
> What is your age?
>>>> myAge=input()
> print:('You will be ' + str(int(myAge)+1)'in a year.')

 >>> print("Hello World")
Hello World
 >>> myname=input("What is your name? ")
What is your name? John
 >>> print ("Your name is ", myname)
Your name is  John

...you can find code samples in the *quick tutorial listed here: 
https://wiki.python.org/moin/BeginnersGuide/Programmers
*http://hetland.org/writing/instant-python.html


From vincent at vincentdavis.net  Thu Nov 19 22:45:08 2015
From: vincent at vincentdavis.net (Vincent Davis)
Date: Thu, 19 Nov 2015 20:45:08 -0700
Subject: shorten "compress" long integer to short ascii.
Message-ID: <CALyJZZUzeUPikpXLQpJ_=hLb6WC-SXUN3pSi8DqPmq0b8Ba+QQ@mail.gmail.com>

My goal is to shorten a long integer into a shorter set of characters.
Below is what I have which gets me about a 45-50% reduction. Any suggestion
on how to improve upon this?
I not limited to ascii but I didn't see how going to utf8 would help.
The resulting string needs to be something I could type/paste into twitter
for example.

On a side note string.punctuation contains "\\" what is \\ ?

import string
import random

# Random int to shorten
r = random.getrandbits(300)
lenofr = len(str(r))

l = string.ascii_lowercase + string.ascii_uppercase +
'!"#$%&\'()*+,-./:;<=>?@[]^_`{|}~'
n = [str(x) for x in list(range(10,93))]
decoderdict = dict(zip(l, n))
encoderdict = dict(zip(n, l))

def encoder(integer):
    s = str(integer)
    ls = len(s)
    p = 0
    code = ""
    while p < ls:
        if s[p:p+2] in encoderdict.keys():
            code = code + encoderdict[s[p:p+2]]
            p += 2
        else:
            code = code + s[p]
            p += 1
    return code

def decoder(code):
    integer = ""
    for c in code:
        if c.isdigit():
            integer = integer + c
        else:
            integer = integer + decoderdict[c]
    return int(integer)

short = encoder(r)
backagain = decoder(short)

print(lenofr, len(short), len(short)/lenofr, r==backagain)


From Seymore4Head at Hotmail.invalid  Thu Nov 19 23:05:12 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Thu, 19 Nov 2015 23:05:12 -0500
Subject: Generate a random  list of numbers
Message-ID: <cq5t4bld6vop5fq3gsqj3cfg9fpbcisr4u@4ax.com>

Why does a work and b doesn't?  What I was trying to accomplish with b
is to get a random list (of random length) that could have digits
repeat.  

I got idea for both methods from the Internet.  I do see that one uses
brackets and the other doesn't, but I don't know the difference.

import random
for i in range (5):
    a = random.sample(range(10), random.randrange(3,6))
    print a

for i in range (5):    
    b = [random.randrange (10), random.randrange(4,8)]
    print b



From no.email at nospam.invalid  Thu Nov 19 23:27:07 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Thu, 19 Nov 2015 20:27:07 -0800
Subject: shorten "compress" long integer to short ascii.
References: <mailman.503.1447991136.16136.python-list@python.org>
Message-ID: <871tbll2hw.fsf@nightsong.com>

Vincent Davis <vincent at vincentdavis.net> writes:
> My goal is to shorten a long integer into a shorter set of characters.
> Below is what I have which gets me about a 45-50% reduction. Any suggestion
> on how to improve upon this?

You can't improve much.  A decimal digit carries log(10,2)=3.32 bits
of information.  A reasonable character set for Twitter-style links
might have 80 or so characters (upper/lower alphabetic, digits, and
a dozen or so punctuation characters), or log(80,2)=

> I not limited to ascii but I didn't see how going to utf8 would help.

If you could use Unicode characters like Chinese ideographs, that gives
you a much larger alphabet to work with, so you'd need fewer chars
displayed in the link, but they'd be hard for most people to type.

> l = string.ascii_lowercase + string.ascii_uppercase +
> '!"#$%&\'()*+,-./:;<=>?@[]^_`{|}~'

OK, 83 chars, but it may not be ok to use some of them like #, /, and ?,
since they can have special meanings in urls.

Your algorithm looks basically ok though I didn't examine it closely.
Here is my shortened version:

  import string

  # alphabet here is 83 chars
  alphabet = string.ascii_lowercase + \
       string.ascii_uppercase +'!"#$%&\'()*+,-./:;<=>?@[]^_`{|}~'
  alphabet_size = len(alphabet)

  decoderdict = dict((b,a) for a,b in enumerate(alphabet))

  def encoder(integer):
      a,b = divmod(integer, alphabet_size)
      if a == 0: return alphabet[b]
      return encoder(a) + alphabet[b]

  def decoder(code):
    return reduce(lambda n,d: n*alphabet_size + decoderdict[d], code, 0)

  def test():
      n = 92928729379271
      short = encoder(n)
      backagain = decoder(short)
      nlen = len(str(n))
      print (nlen, len(short), float(len(short))/nlen)
      assert n==backagain, (n,short,b)

  test()


From steve at pearwood.info  Thu Nov 19 23:38:36 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 20 Nov 2015 15:38:36 +1100
Subject: Generate a random  list of numbers
References: <cq5t4bld6vop5fq3gsqj3cfg9fpbcisr4u@4ax.com>
Message-ID: <564ea3cd$0$1605$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 03:05 pm, Seymore4Head wrote:

> Why does a work and b doesn't?  What I was trying to accomplish with b
> is to get a random list (of random length) that could have digits
> repeat.
> 
> I got idea for both methods from the Internet.  I do see that one uses
> brackets and the other doesn't, but I don't know the difference.
> 
> import random
> for i in range (5):
>     a = random.sample(range(10), random.randrange(3,6))
>     print a

Break it up, step by step.

range(10) produces a list from 0 to 9. random.randrange(3, 6) produces a
single integer from 3 to 5 (6 is excluded). Let's say by chance it produces
the number 4.

Then random.sample takes the list, and the integer 4, and selects 4 values
at random from the list. Say, something like this:

[8, 6, 7, 0]

Note that random.sample does NOT repeat selections. The numbers will always
be unique.



> for i in range (5):
>     b = [random.randrange (10), random.randrange(4,8)]
>     print b

As above, run through this step by step.

random.randrange(10) produces a single number at random between 0 and 9 (10
is excluded). Let's say it picks 8. 

random.randrange(4,8) produces a single number at random between 4 and 7 (8
is excluded). Let's say it picks 5.

Then b is set to the list [8, 5].

This list will always have two items.



If you want a random number of digits that might repeat:

[random.randrange(10) for i in range(random.randrange(1, 21))]

will produce a random number between 1 and 20 (21 is excluded). Let's say it
picks 6.

then range(6) produces the list [0, 1, 2, 3, 4, 5], and "for i in range..."
will iterate over those values. Although i is not used, this ends up
looping 6 times.

For each loop, random.randrange(10) produces a random digit between 0 and 9
(10 is excluded). So we end up with something like:

[6, 4, 2, 2, 6, 9]

for example.



-- 
Steven



From Seymore4Head at Hotmail.invalid  Fri Nov 20 00:09:19 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Fri, 20 Nov 2015 00:09:19 -0500
Subject: Generate a random  list of numbers
References: <cq5t4bld6vop5fq3gsqj3cfg9fpbcisr4u@4ax.com>
 <564ea3cd$0$1605$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <rmat4btilageb7d5f4nvig5lstu5ssibl4@4ax.com>

On Fri, 20 Nov 2015 15:38:36 +1100, Steven D'Aprano
<steve at pearwood.info> wrote:

>On Fri, 20 Nov 2015 03:05 pm, Seymore4Head wrote:
>
>> Why does a work and b doesn't?  What I was trying to accomplish with b
>> is to get a random list (of random length) that could have digits
>> repeat.
>> 
>> I got idea for both methods from the Internet.  I do see that one uses
>> brackets and the other doesn't, but I don't know the difference.
>> 
>> import random
>> for i in range (5):
>>     a = random.sample(range(10), random.randrange(3,6))
>>     print a
>
>Break it up, step by step.
>
>range(10) produces a list from 0 to 9. random.randrange(3, 6) produces a
>single integer from 3 to 5 (6 is excluded). Let's say by chance it produces
>the number 4.
>
>Then random.sample takes the list, and the integer 4, and selects 4 values
>at random from the list. Say, something like this:
>
>[8, 6, 7, 0]
>
>Note that random.sample does NOT repeat selections. The numbers will always
>be unique.
>
>
>
>> for i in range (5):
>>     b = [random.randrange (10), random.randrange(4,8)]
>>     print b
>
>As above, run through this step by step.
>
>random.randrange(10) produces a single number at random between 0 and 9 (10
>is excluded). Let's say it picks 8. 
>
>random.randrange(4,8) produces a single number at random between 4 and 7 (8
>is excluded). Let's say it picks 5.
>
>Then b is set to the list [8, 5].
>
>This list will always have two items.
>
>
>
>If you want a random number of digits that might repeat:
>
>[random.randrange(10) for i in range(random.randrange(1, 21))]
>
>will produce a random number between 1 and 20 (21 is excluded). Let's say it
>picks 6.
>
>then range(6) produces the list [0, 1, 2, 3, 4, 5], and "for i in range..."
>will iterate over those values. Although i is not used, this ends up
>looping 6 times.
>
>For each loop, random.randrange(10) produces a random digit between 0 and 9
>(10 is excluded). So we end up with something like:
>
>[6, 4, 2, 2, 6, 9]
>
>for example.

That works.
Thanks


From robertvstepp at gmail.com  Fri Nov 20 00:18:28 2015
From: robertvstepp at gmail.com (boB Stepp)
Date: Thu, 19 Nov 2015 23:18:28 -0600
Subject: failing to run python on my pc
In-Reply-To: <CAGhiGqfU--Fu3rhj3iV43G5tmMAjGf_=UmFiOWyW5-0RuMusug@mail.gmail.com>
References: <CAGhiGqfU--Fu3rhj3iV43G5tmMAjGf_=UmFiOWyW5-0RuMusug@mail.gmail.com>
Message-ID: <CANDiX9K3SO8i5VFGwo5T0Jf_dA_K3w8nDr4Vw=xMkVbsU-=ymw@mail.gmail.com>

On Thu, Nov 19, 2015 at 2:22 PM, Daniel Kasuza <danielkasuza at gmail.com> wrote:
> Dear Sir/Madam
> I am student with University of the people and a beginner in programming.
> My problem is that l have down loaded python 2.7 but l am failing to muse
> it. If l try to to use it, I am getting an option which say run. If l press
> run, it just run and come back to the same option. I want to use it for
> some practice but i am failing.

Your question is rather vague and difficult to understand.  Are you
having difficulty in installing Python 2.7?  If yes, what operating
system are you using?  Did your course or course text book give you
instructions on what to do?  If so, what steps did you accomplish
successfully, and at what step did things stop working?

Or do you have Python installed and then tried to run a program?  What
program and how did you try to run it?  What were the precise results?

You might want to redirect your question to Python Tutor with a much
fuller description of what you tried and what happened:
https://mail.python.org/mailman/listinfo/tutor

This mailing list is targeted towards beginners in Python.  They have
been extremely helpful to me!  But you will have to give much more
detailed information before anyone will be able to assist you.  Also,
the main Python website has many resources, including tutorials as
well as the full docs.  Poke around at www.python.org .  And don't
forget to search the 'Net!  Your exact problem has probably been
encountered many times before ...


-- 
boB


From dieter at handshake.de  Fri Nov 20 02:00:57 2015
From: dieter at handshake.de (dieter)
Date: Fri, 20 Nov 2015 08:00:57 +0100
Subject: PubMed / Entrez
References: <3p1Ylk6Wjgz5vMw@dovecot03.posteo.de>
Message-ID: <87fv01noie.fsf@handshake.de>

<c.buhtz at posteo.jp> writes:

> I am looking for a way to use the PubMed (medical research search
> engine) API (aka Entrez) with Python3.

I am using (on Python 2) "urllib" and "lxml" to interface with
the NCBI E-utilities.



From dieter at handshake.de  Fri Nov 20 02:18:02 2015
From: dieter at handshake.de (dieter)
Date: Fri, 20 Nov 2015 08:18:02 +0100
Subject: Why doesn't this method have access to its "self" argument?
References: <db6apoFgvjlU1@mid.individual.net>
Message-ID: <87bnapnnpx.fsf@handshake.de>

Robert Latest via Python-list <python-list at python.org> writes:

> I'm still trying to find a simple way to implement a method (but not the
> full class) in C. Suggestions I have recived so far are good, but seem to be
> over the top for such a (seemingly) simple problem.

The C interface of Python is far from simple - and it is very easy
to make severe and difficult to analyse errors. Therefore, I confirm
an advice you already got: use "cython" (which drastically reduces
the danger of errors).

A "method" in Python is just a function which happens to get automatically
on call an additional first arguemnt: the object's reference. Apparently,
this automatism does not work for C implemented functions (at least
in Python 2). You would need to use a (so called) "descriptor" wrapper
to do this explicitely.

The easiest way (in my view), however would be:

import _my_c_implementation

class C(object):
  def my_method(self, *args, **kw):
    return _my_c_implementation.my_method(self, *args, **kw)


With a descriptor "method" (sketched above), this would become:

class C(object):
  my_method = method(_my_c_implementation.my_method)



From hkrss at gmail.com  Fri Nov 20 02:43:04 2015
From: hkrss at gmail.com (HKRSS)
Date: Fri, 20 Nov 2015 08:43:04 +0100
Subject: How To Create A Endles List Of Lists In Python...???
Message-ID: <n2miu8$fl4$1@ls237.t-com.hr>

Thanks In Advance, Robert...;) 





From karthik.sharma at gmail.com  Fri Nov 20 02:47:52 2015
From: karthik.sharma at gmail.com (Karthik Sharma)
Date: Thu, 19 Nov 2015 23:47:52 -0800 (PST)
Subject: Plotting a timeseris graph from pandas dataframe using matplotlib
Message-ID: <b82dabb0-9e8a-4fcd-b7f3-495ad9ffa057@googlegroups.com>

I have the following data in a csv file 

       SourceID    BSs	 hour	Type
        7208	   87	  11	MAIN
        11060	   67	  11	MAIN
        3737	   88	  11	MAIN
        9683	   69	  11	MAIN
        9276	   88	  11	MAIN
        7754	   62	  11	MAIN
        11111	   80	  12	MAIN
        9276	   88	  12	MAIN
        11111	   80	  12	MAIN
        6148	   70	  12	MAIN
        11111	   80	  12	MAIN
        9866	   80	  12	SUB
        9866	   78	  13	MAIN
        9866	   78	  13	SUB
        20729	   82	  14	MAIN
        9276	   88	  14	MAIN
        11111	   80	  15	MAIN
        20190	   55	  15	MAIN
        7208	   85	  15	MAIN
        7208	   86	  15	MAIN
        7754	   61	  16	MAIN
        8968	   91	  16	MAIN
        3737	   88	  16	MAIN
        9683	   69	  16	MAIN
        20729	   81	  16	MAIN
        9704	   68	  16	MAIN
        11111	   87	  16	PAN


I have the following python code.I want to plot a graph with the following specifications.

For each `SourceID` and `Type` I want to plot a graph of `BSs` over time. I would prefer if each `SourceID` and `Type` is a subplot on single plot.I have tried a lot of options using groupby, but can't seem to get it work.

    import numpy as np
    import pandas as pd
    import matplotlib.pyplot as plt

    
    
    COLLECTION = 'NEW'
    DATA = r'C:\Analysis\Test\{}'.format(COLLECTION)
    INPUT_FILE = DATA + r'\in.csv'
    OUTPUT_FILE = DATA + r'\out.csv'
    
    
    with open(INPUT_FILE) as fin:
        df = pd.read_csv(INPUT_FILE,
                      usecols=["SourceID", 'hour','BSs','Type'],
                      header=0)
    
        df.drop_duplicates(inplace=True)
    
        df.reset_index(inplace=True)

   


From dieter at handshake.de  Fri Nov 20 02:49:12 2015
From: dieter at handshake.de (dieter)
Date: Fri, 20 Nov 2015 08:49:12 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
Message-ID: <877fldnm9z.fsf@handshake.de>

Chris Angelico <rosuav at gmail.com> writes:

> On Fri, Nov 20, 2015 at 5:42 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> BartC on the other hand is just complaining about an aspect of Python
>> that is legitimately controversial.
>
> IMO it's controversial mainly because there's an easy and obvious
> syntax for early binding, but late binding doesn't have syntactic
> support, and all the options are imperfect.

I do not think that we should get additional syntax for lately bound
default values. It would explicitely introduce the concepts
early versus late binding which are likely difficult to understand
by many users.

In addition, the last few days have had two discussions in this list
demonstrating the conceptial difficulties of late binding -- one of them:

      Why does "[lambda x: i * x for i in range(4)]" gives
      a list of essentially the same functions?


Note as well, that it is difficult to define what "late binding"
should mean in non-trivial cases:

   def f(..., a=<some complex expression, involving variable references>)

   If "a" is lately bound, when are bound the variables involved
   in its defining expression?

   If they are early bound, you get the same effect as with realy
   bound default parameters: calling the function can change non local
   objects which may lead to surprises.

   If they are lately bound, the references may no longer be
   resolvable or (worse) may resolve to unexpected objects.


If you need late binding, you might use something like this:

   class Late(object):
     def __init__(self, obj): self.obj = obj
     def bind:
       from copy import deepcopy
       return deepcopy(obj)
     def __repr__: ...

   def f(..., a=Late(<expr>)):
     ...
     a = a.bind()
     ...

Of course, you could define a decorator which performs the
"bind" calls automatically.
    





From hkrss at gmail.com  Fri Nov 20 03:13:38 2015
From: hkrss at gmail.com (HKRSS)
Date: Fri, 20 Nov 2015 09:13:38 +0100
Subject: How To Create A Endles List Of Lists In Python...???
References: <n2miu8$fl4$1@ls237.t-com.hr>
Message-ID: <n2mknk$ges$1@ls237.t-com.hr>

I Think That There Are Two Ways:
1)Harder Way Use Procedural C...
2)Easier Way Use LISP...

"HKRSS" <hkrss at gmail.com> wrote in message 
news:n2miu8$fl4$1 at ls237.t-com.hr...
> Thanks In Advance, Robert...;)
>
> 





From eryksun at gmail.com  Fri Nov 20 03:43:13 2015
From: eryksun at gmail.com (eryksun)
Date: Fri, 20 Nov 2015 02:43:13 -0600
Subject: non-blocking getkey?
In-Reply-To: <564DF94E.8020302@gmail.com>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de>
 <564DF94E.8020302@gmail.com>
Message-ID: <CACL+1atXXZvR9RD36cZ_NUvMniN=DFs73YqLFsq2G_8oR+19eg@mail.gmail.com>

On Thu, Nov 19, 2015 at 10:31 AM, Michael Torrie <torriem at gmail.com> wrote:
> One windows it might be possible to use the win32 api to enumerate the
> windows, find your console window and switch to it.

You can call GetConsoleWindow [1] and then SetForegroundWindow [2].

    import os
    import sys

    try:
        import tkinter
        from tkinter import filedialog
    except ImportError:
        import Tkinter as tkinter
        import tkFileDialog as filedialog
        input = raw_input

    if sys.platform == 'win32':
        import ctypes

        kernel32 = ctypes.WinDLL('kernel32')
        user32 = ctypes.WinDLL('user32')

        def setfgwin():
            hcon = kernel32.GetConsoleWindow()
            if hcon and user32.SetForegroundWindow(hcon):
                return True
            return False

    def get_filename():
        filename = filedialog.askopenfilename()
        setfgwin()
        return os.path.normpath(filename)

    if __name__ == '__main__':
        root = tkinter.Tk()
        root.withdraw()
        filename = get_filename()
        print('filename: %s' % filename)
        input('press enter...')

[1]: https://msdn.microsoft.com/en-us/library/ms683175
[2]: https://msdn.microsoft.com/en-us/library/ms633539


From harvesting at is.invalid  Fri Nov 20 03:49:21 2015
From: harvesting at is.invalid (Jussi Piitulainen)
Date: Fri, 20 Nov 2015 10:49:21 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.508.1448005763.16136.python-list@python.org>
Message-ID: <lf5bnapm4xa.fsf@ling.helsinki.fi>

dieter writes:
> Chris Angelico writes:
>
>> IMO it's controversial mainly because there's an easy and obvious
>> syntax for early binding, but late binding doesn't have syntactic
>> support, and all the options are imperfect.
>
> I do not think that we should get additional syntax for lately bound
> default values. It would explicitely introduce the concepts early
> versus late binding which are likely difficult to understand by many
> users.

I'm confused by the term. I don't like it one bit.

"Early binding" of a default value seems to mean that the expression
that produces the default value of a function parameter is evaluated
when the function is defined. "Late binding" seems to mean that the
expression is evaluated when the function is called.

In both cases the actual binding of the parameter to the value (either
the default or an actual argument) is established when the function is
called. Several different bindings of that same parameter to different
values can hold simultaneously, so the *binding* has to be conceptually
"late". Because recursion.

Why isn't the evaluation of the default expression called evaluation?
Or at least something that doesn't already mean something else that is
as crucially important as, well, I've already given up on talking about
REDACTED and REDACTED in connection with Python, and here I see related
established terminology used for something else *for no reason that I
can see*.

I see no *need* to call this other thing "binding".


From __peter__ at web.de  Fri Nov 20 03:53:06 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 20 Nov 2015 09:53:06 +0100
Subject: How To Create A Endles List Of Lists In Python...???
References: <n2miu8$fl4$1@ls237.t-com.hr>
Message-ID: <n2mn1i$k2q$1@ger.gmane.org>

HKRSS wrote:

> Thanks In Advance, Robert...;)

>>> list_of_lists = []
>>> list_of_lists.append(list_of_lists)
>>> list_of_lists[0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0]
[[...]]




From steephenmyroz at gmail.com  Fri Nov 20 04:52:53 2015
From: steephenmyroz at gmail.com (marozzyye)
Date: Fri, 20 Nov 2015 10:52:53 +0100
Subject: download
Message-ID: <9gn0ssui8hfaavc4qw2b9x2b.1448013173332@email.android.com>

i am about to download python 3.5.0 but there are three options 
1.windows x86 web-based installer
2.windows x86 executable installer
3.windows x86 embeddable zip file
 i have tried no.1 but while installing there was an error. so which do i pick?

From hkrss at gmail.com  Fri Nov 20 06:00:27 2015
From: hkrss at gmail.com (HKRSS)
Date: Fri, 20 Nov 2015 12:00:27 +0100
Subject: How To Create A Endles List Of Lists In Python...???
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
Message-ID: <n2mugp$kt1$1@ls237.t-com.hr>


"Peter Otten" <__peter__ at web.de> wrote in message 
news:mailman.510.1448009596.16136.python-list at python.org...
> HKRSS wrote:
>
>> Thanks In Advance, Robert...;)
>
>>>> list_of_lists = []
>>>> list_of_lists.append(list_of_lists)
>>>> list_of_lists[0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0]
> [[...]]
>

Sorry For Bad Question, But I need List Of Lists That I Can
Acces Horyzontaly, Not In The Deep(But This IS Not All,
I End That Evey List In List Of Lists Can Be A List...

Thanks In Advance...
Robert..;) 





From bc at freeuk.com  Fri Nov 20 06:59:20 2015
From: bc at freeuk.com (BartC)
Date: Fri, 20 Nov 2015 11:59:20 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2n1qp$m35$1@dont-email.me>

On 20/11/2015 01:05, Steven D'Aprano wrote:
> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
>
>> On 19/11/2015 16:01, Steven D'Aprano wrote:
> [...]
>
>> The whole concept of 'mutable' default is alien to me. A default is just
>> a convenient device to avoid having to write:
>>
>>     fn(0) or fn("") or fn([])
>
> Says who?

People who want to avoid having to write:

      fn(0) or fn("") or fn([])

> Here's another use for function defaults, as static storage:
>
>
> # Ackermann's function
> def ack(m, n, _memo={}):
>      key = m, n
>      if key not in _memo:
>          if m==0: v = n + 1
>          elif n==0: v = ack(m-1, 1)
>          else: v = ack(m-1, ack(m, n-1))
>          _memo[key] = v
>      return _memo[key]
>
>
> This is a quick and easy way to memoise a function which would otherwise be
> horribly slow. And it only works because _memo is bound to a mutable object
> once, and once only.

We're arguing at cross-purposes then since you are obviously interested 
in these esoteric aspects, but all I want to do is avoid remembering a 
long list of defaults. Here's an example from another language, a 
function I'm working on at the minute:

function asklist(caption,&data,n=1, rows=10, width=50, flags="",
                  buttons=(), tablist=(), heading="")=

9 parameters, 7 of them optional. This is designed to be used with 
keyword arguments which is where the default values come into their own, 
as you don't need to remember positional order either.

Very basic stuff and very obvious what it's for. Notice some defaults 
are () (empty lists here), which are the ones that cause bother in Python.

(Here, however, the language doesn't like you doing in-place 
modification of a parameter unless the '&' is used, in which case you 
wouldn't be able to assign a default value such as () as you can only 
pass l-values.)


> def test(arg=[]):
>      arg.append(1)
>      return len(arg)
>
>
> The binding arg=[] is NOT inside the body of the function. Therefore, it is
> NOT executed repeatedly, but only once.

OK, so the "=" is misleading if not a lie.

>> So you didn't bother reading the LRM either!
>
> LRM? Left Right Manual?

Language Reference Manual.

>>>> That [] doesn't look like an object that could change.
>>>
>>> Of course it does.
>>
>> You've lost me know.

> a = []
> a.append(1)
>
> Are you shocked to learn that a is no longer an empty list?

No. But I would be surprised if, after this point, [] is no longer an 
empty list either!

No, forget that; by now, I wouldn't be surprised at all!

(That [] isn't changed is probably thanks to [] being implemented with 
the BUILD_LIST byte-code, which constructs a brand-new empty list each 
time. So the next time [] is used, it will be a different one from the 
one that has just been appended to.

In my language, a construct such as [10,20,30] is evaluated just once at 
start-up. If Python did the same, then I suspect such a literal could 
conceivably be changed if just "=" was used to ______[1] it to 'a'.)

([1] To avoid further argument, insert your own choice of jargon here.)

-- 
Bartc


From ned at nedbatchelder.com  Fri Nov 20 07:12:47 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Fri, 20 Nov 2015 04:12:47 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <n2n1qp$m35$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
Message-ID: <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>

On Friday, November 20, 2015 at 6:59:54 AM UTC-5, BartC wrote:
> On 20/11/2015 01:05, Steven D'Aprano wrote:
> > On Fri, 20 Nov 2015 04:30 am, BartC wrote:
> >
> >> On 19/11/2015 16:01, Steven D'Aprano wrote:
> > [...]
> >
> >> The whole concept of 'mutable' default is alien to me. A default is just
> >> a convenient device to avoid having to write:
> >>
> >>     fn(0) or fn("") or fn([])
> >
> > Says who?
> 
> People who want to avoid having to write:
> 
>       fn(0) or fn("") or fn([])

I think we all understand by now that you are unhappy with what happens
in Python with mutable defaults.  We get it.  You are not alone. Lots of
people are surprised by this.  But it is how Python works.

I'm not sure what your goal is at this point.  Are you:

  1) still unsure what the behavior is, or 
  2) trying to understand why it behaves that way, or
  3) hoping to change Python, or
  4) trying to convince us that your language is better, or
  5) something else?

--Ned.


From marko at pacujo.net  Fri Nov 20 07:28:17 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 20 Nov 2015 14:28:17 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
Message-ID: <877flcrh26.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> On 20/11/2015 01:05, Steven D'Aprano wrote:
>> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
>>> The whole concept of 'mutable' default is alien to me. A default is just
>>> a convenient device to avoid having to write:
>>>
>>>     fn(0) or fn("") or fn([])
>>
>> Says who?
>
> People who want to avoid having to write:
>
>      fn(0) or fn("") or fn([])

Undoubtedly a mutable default value can lead to accidents. However, I
already showed C++ default values can also be mutable and lead to
analogous problems, so the question is not related to Python alone.

If there is a risk of a default [] or {} ending up in the wrong hands,
you can always write your function with a sentinel:

   omitted = object()

   def f(collection=omitted):
       if collection is omitted:
           collection = []
       ...

> We're arguing at cross-purposes then since you are obviously
> interested in these esoteric aspects,

The Ackermann function really is an esoteric example, but the other
example that has been discussed here can make practical use of the
default-value semantics:

   [ lambda x: i * x for i in range(4) ]

which is salvaged with a default value:

   [ lambda x, i=i: i * x for i in range(4) ]

or, more hygienically:

   [ (lambda i=i: lambda x: i * x)() for i in range(4) ]


Even more appropriately, you may expressly want a mutable, singleton
object to be the default:

   def initiate_query(query, database=global_database):

> but all I want to do is avoid remembering a long list of defaults.
> Here's an example from another language, a function I'm working on at
> the minute:
>
> function asklist(caption,&data,n=1, rows=10, width=50, flags="",
>                  buttons=(), tablist=(), heading="")=

One could argue that you should always use a sentinel object for default
values. That also allows you to distinguish between omitted values and
default values:

   def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
               flags=omitted, buttons=omitted, tablist=omitted,
               heading=omitted):

but that would be rather pedantic in most circumstances.


Marko


From bc at freeuk.com  Fri Nov 20 07:39:58 2015
From: bc at freeuk.com (BartC)
Date: Fri, 20 Nov 2015 12:39:58 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
Message-ID: <n2n46v$uj0$1@dont-email.me>

On 20/11/2015 12:12, Ned Batchelder wrote:
> On Friday, November 20, 2015 at 6:59:54 AM UTC-5, BartC wrote:
>> On 20/11/2015 01:05, Steven D'Aprano wrote:
>>> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
>>>
>>>> On 19/11/2015 16:01, Steven D'Aprano wrote:
>>> [...]
>>>
>>>> The whole concept of 'mutable' default is alien to me. A default is just
>>>> a convenient device to avoid having to write:
>>>>
>>>>      fn(0) or fn("") or fn([])
>>>
>>> Says who?
>>
>> People who want to avoid having to write:
>>
>>        fn(0) or fn("") or fn([])
>
> I think we all understand by now that you are unhappy with what happens
> in Python with mutable defaults.  We get it.  You are not alone. Lots of
> people are surprised by this.  But it is how Python works.
>
> I'm not sure what your goal is at this point.  Are you:
>
>    1) still unsure what the behavior is, or
>    2) trying to understand why it behaves that way, or
>    3) hoping to change Python, or
>    4) trying to convince us that your language is better, or
>    5) something else?

Mostly 5. (With a bit of 4. However that language is not something I'm 
selling or pushing. It's just something different used as a contrast.).

What's bothering me is:

* The large amount of mumbo-jumbo used to describe what's going on

* The insistence (I think largely from Steven) that the way this feature 
works is good rather than bad

* The refusal to acknowledge that the def fn(a=[]) syntax is misleading. 
(What value will a have when you call fn()? The true answer is that you 
can't tell.)

* The persistent nonsense that somehow [] is mutable (what happens is 
that [] is assigned to a variable, and /that/ is mutable) (And I will 
probably get some flak now because 'assign' and 'variable' are 
meaningless in Python!)

* And above, where I lay out /why/ people want to use the feature, so 
that the function can take care of some details, even that is refuted.

-- 
Bartc


From bc at freeuk.com  Fri Nov 20 07:53:00 2015
From: bc at freeuk.com (BartC)
Date: Fri, 20 Nov 2015 12:53:00 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <877flcrh26.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
Message-ID: <n2n4ve$1no$1@dont-email.me>

On 20/11/2015 12:28, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:

>> We're arguing at cross-purposes then since you are obviously
>> interested in these esoteric aspects,
>
> The Ackermann function really is an esoteric example, but the other
> example that has been discussed here can make practical use of the
> default-value semantics:

And you go on to give a couple of slightly less esoteric examples! (I 
don't think I've ever written a lambda function in my life.)

> Even more appropriately, you may expressly want a mutable, singleton
> object to be the default:
>
>     def initiate_query(query, database=global_database):

Finally, a down-to-earth example. Here it probably doesn't matter at 
what point 'global_database' gets bound. You know it will always refer 
to the current state of global_database, and you know that it is a data 
structure external to the function even if it is updated from inside.

That is a bit different from an empty list that later is not empty.

>     def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
>                 flags=omitted, buttons=omitted, tablist=omitted,
>                 heading=omitted):
>
> but that would be rather pedantic in most circumstances.

Yes, that's along the lines of what I used do before I had proper 
default values!

Then I had code inside the function to test a parameter and set it as 
needed. I still do this when the default isn't straightforward (where it 
depends on other parameters for example).

-- 
Bartc


From rosuav at gmail.com  Fri Nov 20 08:04:03 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 00:04:03 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2n46v$uj0$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
Message-ID: <CAPTjJmo3vvVuRdb6T3Xk+sHKUAbixosSKK3_hOF5+CexQXtbvA@mail.gmail.com>

On Fri, Nov 20, 2015 at 11:39 PM, BartC <bc at freeuk.com> wrote:
> * The refusal to acknowledge that the def fn(a=[]) syntax is misleading.
> (What value will a have when you call fn()? The true answer is that you
> can't tell.)

It isn't misleading. The default value for the argument is set when
the function is defined, and it is set to the *object* that results
from evaluating the *expression* given. After that, the *object* is
the one you will always get (barring shenanigans) if the argument is
omitted. If the value of that object changes, it changes!

You keep expecting the *value* to be consistent. But what you actually
get is that the *object* is consistent. It's virtually impossible to
guarantee the former, in the face of mutable objects.

> * The persistent nonsense that somehow [] is mutable (what happens is that
> [] is assigned to a variable, and /that/ is mutable) (And I will probably
> get some flak now because 'assign' and 'variable' are meaningless in
> Python!)

What happens is that [] evaluates to an object, and *that object* is
mutable. Python does not store the syntactic element "[]" (empty
list-display), but instead stores (a reference to) the object. It's
exactly the same as:

def fn(a=list()):
    ...

def generate_list():
    return []
def fn(a=generate_list()):
    ...

initial_list = []
def fn(a=initial_list):
    ...

import sys
def fn(a=[x*3+424 for x in range(not sys)]):
    """how ridiculous would you like to go?"""

Every one of these constructs exactly one new list, *when it is
evaluated*, which is at function definition time.

ChrisA


From gandalf at shopzeus.com  Fri Nov 20 08:06:08 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Fri, 20 Nov 2015 14:06:08 +0100
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <n2mugp$kt1$1@ls237.t-com.hr>
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr>
Message-ID: <564F1AC0.5040106@shopzeus.com>


> Sorry For Bad Question, But I need List Of Lists That I Can
> Acces Horyzontaly, Not In The Deep(But This IS Not All,
> I End That Evey List In List Of Lists Can Be A List...
It is not possible to do it with a native list. But you can write your
own iterable that can be iterated forever, and indexed with an integer.

But before you do that: what is this needed for?


From rosuav at gmail.com  Fri Nov 20 08:09:05 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 00:09:05 +1100
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <564F1AC0.5040106@shopzeus.com>
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr> <564F1AC0.5040106@shopzeus.com>
Message-ID: <CAPTjJmpJoktL=OdaCOw3KGukxUKBu+nW+cUFvwv47KCczAKXsg@mail.gmail.com>

On Sat, Nov 21, 2015 at 12:06 AM, Nagy L?szl? Zsolt
<gandalf at shopzeus.com> wrote:
>> Sorry For Bad Question, But I need List Of Lists That I Can
>> Acces Horyzontaly, Not In The Deep(But This IS Not All,
>> I End That Evey List In List Of Lists Can Be A List...
> It is not possible to do it with a native list. But you can write your
> own iterable that can be iterated forever, and indexed with an integer.
>
> But before you do that: what is this needed for?

My crystal ball suggests that defaultdict(list) might be useful here.

ChrisA


From robert.bralic at si.t-com.hr  Fri Nov 20 08:29:35 2015
From: robert.bralic at si.t-com.hr (robert.bralic at si.t-com.hr)
Date: Fri, 20 Nov 2015 05:29:35 -0800 (PST)
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <mailman.513.1448024777.16136.python-list@python.org>
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr>
 <mailman.513.1448024777.16136.python-list@python.org>
Message-ID: <9129317f-5f24-4e28-96de-8567e2d7afe8@googlegroups.com>

Dana petak, 20. studenoga 2015. u 14:06:31 UTC+1, korisnik Nagy L?szl? Zsolt napisao je:
> > Sorry For Bad Question, But I need List Of Lists That I Can
> > Acces Horyzontaly, Not In The Deep(But This IS Not All,
> > I End That Evey List In List Of Lists Can Be A List...
> It is not possible to do it with a native list. But you can write your
> own iterable that can be iterated forever, and indexed with an integer.
> 
> But before you do that: what is this needed for?

To Make A Turing Machine That Accepts A Classes....
(This Is My Idea, And Must Be Published By Me,
And I Don't Respond How I Think Make This Machine)...

Thanks, Robert...;)


From ned at nedbatchelder.com  Fri Nov 20 08:30:21 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Fri, 20 Nov 2015 05:30:21 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <n2n46v$uj0$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
Message-ID: <67bccb9f-6b2f-4ffb-a0e5-71c32587eeb7@googlegroups.com>

On Friday, November 20, 2015 at 7:40:37 AM UTC-5, BartC wrote:
> On 20/11/2015 12:12, Ned Batchelder wrote:
> > On Friday, November 20, 2015 at 6:59:54 AM UTC-5, BartC wrote:
> >> On 20/11/2015 01:05, Steven D'Aprano wrote:
> >>> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
> >>>
> >>>> On 19/11/2015 16:01, Steven D'Aprano wrote:
> >>> [...]
> >>>
> >>>> The whole concept of 'mutable' default is alien to me. A default is just
> >>>> a convenient device to avoid having to write:
> >>>>
> >>>>      fn(0) or fn("") or fn([])
> >>>
> >>> Says who?
> >>
> >> People who want to avoid having to write:
> >>
> >>        fn(0) or fn("") or fn([])
> >
> > I think we all understand by now that you are unhappy with what happens
> > in Python with mutable defaults.  We get it.  You are not alone. Lots of
> > people are surprised by this.  But it is how Python works.
> >
> > I'm not sure what your goal is at this point.  Are you:
> >
> >    1) still unsure what the behavior is, or
> >    2) trying to understand why it behaves that way, or
> >    3) hoping to change Python, or
> >    4) trying to convince us that your language is better, or
> >    5) something else?
> 
> Mostly 5. (With a bit of 4. However that language is not something I'm 
> selling or pushing. It's just something different used as a contrast.).
> 
> What's bothering me is:

Let me try to answer some of these.

> 
> * The large amount of mumbo-jumbo used to describe what's going on

We try not to use mumbo-jumbo, we use terms that can be confusing
sometimes.  This page was recommended early on in this thread:
http://nedbatchelder.com/text/names1.html  It is my best attempt to
lay out many of the issues here.  I hope you have had a chance to
read/watch it.

> * The insistence (I think largely from Steven) that the way this feature 
> works is good rather than bad

I think the fairest summary is that the way this works is better than
the alternatives, when you take into account the desire to keep the
semantics of the language simple.

> * The refusal to acknowledge that the def fn(a=[]) syntax is misleading. 
> (What value will a have when you call fn()? The true answer is that you 
> can't tell.)

I completely agree with you that the syntax surprises people.  Anyone who
claims that it isn't surprising is ignoring the abundant empirical evidence
that people new to Python (and even some who have been using it for a long
time) are surprised by this.

But it is not true that "you can't tell" what value a will have.  You have
been surprised by it, but I am confident that if we could sit together, I
could explain to you what value you would get, and it would be clear to you.
You might not like the answer, and it might not be what you first imagined,
but it is not unpredictable.

> * The persistent nonsense that somehow [] is mutable (what happens is 
> that [] is assigned to a variable, and /that/ is mutable) (And I will 
> probably get some flak now because 'assign' and 'variable' are 
> meaningless in Python!)

As others have explained, [] is a value, a list.  Lists are mutable.

    a = []           # Create an empty list
    a.append(1)      #   and mutate that list.

If we don't agree on this, then please please please go and look at the 
page I linked above.  This is a central concept in Python, and we aren't
going to be able to get anywhere if we can't agree on this.

> * And above, where I lay out /why/ people want to use the feature, so 
> that the function can take care of some details, even that is refuted.

I understand why you want to use the feature.  It would be nice if it
came out the way you (and many others) want.  But it doesn't.

--Ned.


From bc at freeuk.com  Fri Nov 20 09:00:13 2015
From: bc at freeuk.com (BartC)
Date: Fri, 20 Nov 2015 14:00:13 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.493.1447972885.16136.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <mailman.493.1447972885.16136.python-list@python.org>
Message-ID: <n2n8tf$ghu$1@dont-email.me>

On 19/11/2015 22:41, Laura Creighton wrote:
> In a message of Thu, 19 Nov 2015 22:57:10 +0200, Marko Rauhamaa writes:

> Note: Ned Bachelder (who is probably reading this on python-list
> anyway added cc on this mail, as if I am to discuss somebody, however
> briefly, they deserve to hear about it.  Which may irritate him to
> get 2 copies instead of one, but so it goes.  I am talking about
> BartC as well, but since this is his thread, I assume he is here.)

Actually that thread was started by 'fl'.

> Sometimes you want to understand what you are doing.  Sometimes
> you just want to do it.  And sometimes, well, the only real way
> to get an understanding of what you are doing is to do it more.
> This is, in my opinion, Bartc's problem. He doesn't program in
> python enough to understand it more.

That's true. I'll have to do a substantial project soon. But a lot of my 
interest is about comparisons between Python and the languages I work on.

(Especially of speed. Up to now my interpreters have been comfortably 
faster. But with PyPy I might now have do do a bit more work on mine 
next year. This is where a proper application is needed for comparison 
and not small benchmarks.)

I'm also interested in what handy features I can 'borrow' from Python. 
Enough that I was planning a big upgrade earlier this year to bring it 
more into line with how Python works. (/That/ is a good way of learning 
about a language! To try and implement a lookalike.)

But that was changing my language too much (I was losing too many 
features of my own) so it was abandoned. (Perhaps it can be a separate, 
higher level language at some point as I quite like the Python style 
even if I have misgivings about some features.)

> They have the opposite problem of BartC -- they want to be excellent
> programmers without understanding anything, while he wants to
> understand everything before he knows how to write decent python code.

I can already tell you that I will never be able to write 'Pythonic' 
code if that is what you mean by 'decent'. But at least everyone will be 
able to understand it!

-- 
Bartc


From vincent at vincentdavis.net  Fri Nov 20 09:18:55 2015
From: vincent at vincentdavis.net (Vincent Davis)
Date: Fri, 20 Nov 2015 07:18:55 -0700
Subject: shorten "compress" long integer to short ascii.
In-Reply-To: <871tbll2hw.fsf@nightsong.com>
References: <mailman.503.1447991136.16136.python-list@python.org>
 <871tbll2hw.fsf@nightsong.com>
Message-ID: <CALyJZZUPq+6XtkHggdegz28xiGCAOcnJ=ruJ5tFwjfR0c8jX5w@mail.gmail.com>

On Thu, Nov 19, 2015 at 9:27 PM, Paul Rubin <no.email at nospam.invalid> wrote:

> You can't improve much.  A decimal digit carries log(10,2)=3.32 bits
> of information.  A reasonable character set for Twitter-style links
> might have 80 or so characters (upper/lower alphabetic, digits, and
> a dozen or so punctuation characters), or log(80,2)=
>

?Where do I find out more about the how to calculate information per digit?
?
Lots of nice little tricks you used below. Thanks for sharing.


> Here is my shortened version:
>
>   import string
>
>   # alphabet here is 83 chars
>   alphabet = string.ascii_lowercase + \
>        string.ascii_uppercase +'!"#$%&\'()*+,-./:;<=>?@[]^_`{|}~'
>   alphabet_size = len(alphabet)
>
>   decoderdict = dict((b,a) for a,b in enumerate(alphabet))
>
>   def encoder(integer):
>       a,b = divmod(integer, alphabet_size)
>       if a == 0: return alphabet[b]
>       return encoder(a) + alphabet[b]
>
>   def decoder(code):
>     return reduce(lambda n,d: n*alphabet_size + decoderdict[d], code, 0)
>
>   def test():
>       n = 92928729379271
>       short = encoder(n)
>       backagain = decoder(short)
>       nlen = len(str(n))
>       print (nlen, len(short), float(len(short))/nlen)
>       assert n==backagain, (n,short,b)
>
>   test()
>




Vincent Davis
720-301-3003


From breamoreboy at yahoo.co.uk  Fri Nov 20 09:31:18 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Fri, 20 Nov 2015 14:31:18 +0000
Subject: download
In-Reply-To: <vu8u4b9luk5jrja25krkemesio461id0r9@4ax.com>
References: <9gn0ssui8hfaavc4qw2b9x2b.1448013173332@email.android.com>
 <vu8u4b9luk5jrja25krkemesio461id0r9@4ax.com>
Message-ID: <n2nasa$t32$1@ger.gmane.org>

On 20/11/2015 13:48, Dennis Lee Bieber wrote:
> On Fri, 20 Nov 2015 10:52:53 +0100, marozzyye <steephenmyroz at gmail.com>
> declaimed the following:
>
>> i am about to download python 3.5.0 but there are three options
>> 1.windows x86 web-based installer
>> 2.windows x86 executable installer
>> 3.windows x86 embeddable zip file
>> i have tried no.1 but while installing there was an error. so which do i pick?
>
> 	A) If you are running Windows XP, NONE OF THE ABOVE. 3.5 does not run
> on WinXP
>
> 	B) What site is offering those? I just went to python.org, and the 3.5
> download button (just the one -- no options for type of file) only provides
> a downloadable EXE installer (note: I normally use the ActiveState
> installers rather than python.org)
>

Compare https://www.python.org/downloads/ which I believe is being 
referred to above, to https://www.python.org/ and hover your mouse over 
"downloads" and then "Python 3.5.0", this offers a web install exe, to 
https://www.python.org/downloads/windows/ which offers everything 
including the kitchen sink.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From random832 at fastmail.com  Fri Nov 20 09:32:51 2015
From: random832 at fastmail.com (Random832)
Date: Fri, 20 Nov 2015 14:32:51 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me> <9v7u4b1i0433efj1ineabik9p0e4ke0qop@4ax.com>
Message-ID: <n2naui$lsq$1@ger.gmane.org>

On 2015-11-20, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> 	You can substitute		list()	where ever you use	[] with no
> effective change in the semantics. (I wouldn't be surprised if the parser
> was doing that behind the scenes anyway).

No, because list() does a name lookup on "list" (which is the primary issue
behind every request for frozendict/frozenset literals)



From random832 at fastmail.com  Fri Nov 20 09:35:33 2015
From: random832 at fastmail.com (Random832)
Date: Fri, 20 Nov 2015 14:35:33 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <n2n4ve$1no$1@dont-email.me>
Message-ID: <n2nb3l$lsq$2@ger.gmane.org>

On 2015-11-20, BartC <bc at freeuk.com> wrote:
> Finally, a down-to-earth example. Here it probably doesn't matter at 
> what point 'global_database' gets bound. You know it will always refer 
> to the current state of global_database, and you know that it is a data 
> structure external to the function even if it is updated from inside.
>
> That is a bit different from an empty list that later is not empty.

Why is it different? The only difference is that you're thinking of it as "this
particular database" rather than "a database containing this particular data",
but I'd argue you can say the same for the list.



From airween at gmail.com  Fri Nov 20 09:52:27 2015
From: airween at gmail.com (Ervin =?utf-8?Q?Heged=C3=BCs?=)
Date: Fri, 20 Nov 2015 15:52:27 +0100
Subject: String format - resolve placeholders names
Message-ID: <20151120145227.GB13994@arxnet.hu>

Hi,

Python has a good string formatter, eg. I can do this:

s = "{who} likes {what}"
d = {'who': "Adam", 'what': "ants"}
s.format(**d)

result:
'Adam likes ants'

Is it possible, and if yes, how to resolve the placeholders names
in string?

There is a know method:

d1 = {'who1': "Adam", 'what1': "ants"}
try:
    s.format(**d1)
except KeyError:
    print("keyword missing")

(gives 'keyword missing' as result).


But is there any other (direct) way, which keywords exists in
string?


Thanks,


a.




From rosuav at gmail.com  Fri Nov 20 10:06:11 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 02:06:11 +1100
Subject: String format - resolve placeholders names
In-Reply-To: <20151120145227.GB13994@arxnet.hu>
References: <20151120145227.GB13994@arxnet.hu>
Message-ID: <CAPTjJmoBY=tN3-_AnyrC90QJY6J8fWv6uuC=ORwBknvfi8FYWw@mail.gmail.com>

On Sat, Nov 21, 2015 at 1:52 AM, Ervin Heged?s <airween at gmail.com> wrote:
> Python has a good string formatter, eg. I can do this:
>
> s = "{who} likes {what}"
> d = {'who': "Adam", 'what': "ants"}
> s.format(**d)
>
> result:
> 'Adam likes ants'
>
> Is it possible, and if yes, how to resolve the placeholders names
> in string?
>
> There is a know method:
>
> d1 = {'who1': "Adam", 'what1': "ants"}
> try:
>     s.format(**d1)
> except KeyError:
>     print("keyword missing")
>
> (gives 'keyword missing' as result).
>
>
> But is there any other (direct) way, which keywords exists in
> string?

I think what you're asking for can be done using format_map with a
custom mapping object:

>>> class IdentiMap:
...     def __init__(self):
...         self.keys = []
...     def __getitem__(self, key):
...         self.keys.append(key)
...
>>> m = IdentiMap()
>>> "{who} likes {what}".format_map(m)
'None likes None'
>>> m.keys
['who', 'what']

Does that help?

ChrisA


From airween at gmail.com  Fri Nov 20 10:53:00 2015
From: airween at gmail.com (Ervin =?utf-8?Q?Heged=C3=BCs?=)
Date: Fri, 20 Nov 2015 16:53:00 +0100
Subject: String format - resolve placeholders names
In-Reply-To: <CAPTjJmoBY=tN3-_AnyrC90QJY6J8fWv6uuC=ORwBknvfi8FYWw@mail.gmail.com>
References: <20151120145227.GB13994@arxnet.hu>
 <CAPTjJmoBY=tN3-_AnyrC90QJY6J8fWv6uuC=ORwBknvfi8FYWw@mail.gmail.com>
Message-ID: <20151120155300.GB14645@arxnet.hu>

Hello Chris,

On Sat, Nov 21, 2015 at 02:06:11AM +1100, Chris Angelico wrote:
> On Sat, Nov 21, 2015 at 1:52 AM, Ervin Heged?s <airween at gmail.com> wrote:
> > Python has a good string formatter, eg. I can do this:
> >
> > s = "{who} likes {what}"
> > d = {'who': "Adam", 'what': "ants"}
> > s.format(**d)

...

> > But is there any other (direct) way, which keywords exists in
> > string?
> 
> I think what you're asking for can be done using format_map with a
> custom mapping object:
> 
> >>> class IdentiMap:
> ...     def __init__(self):
> ...         self.keys = []
> ...     def __getitem__(self, key):
> ...         self.keys.append(key)
> ...
> >>> m = IdentiMap()
> >>> "{who} likes {what}".format_map(m)
> 'None likes None'
> >>> m.keys
> ['who', 'what']
> 
> Does that help?

absolutely, many thanks again!


a.
 


From __peter__ at web.de  Fri Nov 20 10:53:47 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 20 Nov 2015 16:53:47 +0100
Subject: String format - resolve placeholders names
References: <20151120145227.GB13994@arxnet.hu>
Message-ID: <n2nfme$hfn$1@ger.gmane.org>

Ervin Heged?s wrote:

> Python has a good string formatter, eg. I can do this:
> 
> s = "{who} likes {what}"
> d = {'who': "Adam", 'what': "ants"}
> s.format(**d)
> 
> result:
> 'Adam likes ants'
> 
> Is it possible, and if yes, how to resolve the placeholders names
> in string?

>>> import string
>>> for item in string.Formatter().parse("{who} likes {what}"):
...     print(item)
... 
('', 'who', '', None)
(' likes ', 'what', '', None)




From invalid at invalid.invalid  Fri Nov 20 10:55:54 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 20 Nov 2015 15:55:54 +0000 (UTC)
Subject: shorten "compress" long integer to short ascii.
References: <mailman.503.1447991136.16136.python-list@python.org>
 <871tbll2hw.fsf@nightsong.com>
 <mailman.517.1448029163.16136.python-list@python.org>
Message-ID: <n2nfq9$rl6$1@reader1.panix.com>

On 2015-11-20, Vincent Davis <vincent at vincentdavis.net> wrote:
> On Thu, Nov 19, 2015 at 9:27 PM, Paul Rubin <no.email at nospam.invalid> wrote:
>
>> You can't improve much.  A decimal digit carries log(10,2)=3.32 bits
>> of information.  A reasonable character set for Twitter-style links
>> might have 80 or so characters (upper/lower alphabetic, digits, and
>> a dozen or so punctuation characters), or log(80,2)=
>>
>
> ?Where do I find out more about the how to calculate information per
> digit?

There are 10 possible states for a decimal digit.

The number of digits required to represent N states in base M is
log(N,M).

-- 
Grant Edwards               grant.b.edwards        Yow! Are we on STRIKE yet?
                                  at               
                              gmail.com            


From invalid at invalid.invalid  Fri Nov 20 10:58:59 2015
From: invalid at invalid.invalid (Grant Edwards)
Date: Fri, 20 Nov 2015 15:58:59 +0000 (UTC)
Subject: How To Create A Endles List Of Lists In Python...???
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr>
Message-ID: <n2ng03$rl6$2@reader1.panix.com>

On 2015-11-20, HKRSS <hkrss at gmail.com> wrote:
>
> Sorry For Bad Question, But I need List Of Lists That I Can
> Acces Horyzontaly, Not In The Deep(But This IS Not All,
> I End That Evey List In List Of Lists Can Be A List...
>
> Thanks In Advance...
> Robert..;) 

Not only was that genuine frontier gibberish, it expressed...
something?

-- 
Grant Edwards               grant.b.edwards        Yow! I feel partially
                                  at               hydrogenated!
                              gmail.com            


From ian.g.kelly at gmail.com  Fri Nov 20 11:16:45 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 09:16:45 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <877flcrh26.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
Message-ID: <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>

On Fri, Nov 20, 2015 at 5:28 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> The Ackermann function really is an esoteric example, but the other
> example that has been discussed here can make practical use of the
> default-value semantics:
>
>    [ lambda x: i * x for i in range(4) ]
>
> which is salvaged with a default value:
>
>    [ lambda x, i=i: i * x for i in range(4) ]
>
> or, more hygienically:
>
>    [ (lambda i=i: lambda x: i * x)() for i in range(4) ]

Note that this last version could be rewritten as:

    [ (lambda i: lambda x: i * x)(i) for i in range(4) ]

At which point the default value semantics are no longer needed.

> One could argue that you should always use a sentinel object for default
> values. That also allows you to distinguish between omitted values and
> default values:
>
>    def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
>                flags=omitted, buttons=omitted, tablist=omitted,
>                heading=omitted):
>
> but that would be rather pedantic in most circumstances.

I think that would be bad design; in general, you shouldn't *need* to
distinguish whether the value was omitted, because it should always be
possible to explicitly pass the default value.


From ian.g.kelly at gmail.com  Fri Nov 20 11:18:44 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 09:18:44 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <n2n46v$uj0$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
Message-ID: <CALwzidmfyGRUrZLd0uoJo=2EFU+cPXGhUnNB4xT00ssmnhLSdQ@mail.gmail.com>

On Fri, Nov 20, 2015 at 5:39 AM, BartC <bc at freeuk.com> wrote:
> * The persistent nonsense that somehow [] is mutable (what happens is that
> [] is assigned to a variable, and /that/ is mutable) (And I will probably
> get some flak now because 'assign' and 'variable' are meaningless in
> Python!)

I think the problem here is that you're talking as if [] is a unique
value, which it isn't. [] is a list display that *constructs* a list,
not a list itself.


From rosuav at gmail.com  Fri Nov 20 11:24:07 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 03:24:07 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>
Message-ID: <CAPTjJmozN9YOF-aMecR0+m2wUQncKQPaJHYw32w7nHkKaYKF_w@mail.gmail.com>

On Sat, Nov 21, 2015 at 3:16 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> One could argue that you should always use a sentinel object for default
>> values. That also allows you to distinguish between omitted values and
>> default values:
>>
>>    def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
>>                flags=omitted, buttons=omitted, tablist=omitted,
>>                heading=omitted):
>>
>> but that would be rather pedantic in most circumstances.
>
> I think that would be bad design; in general, you shouldn't *need* to
> distinguish whether the value was omitted, because it should always be
> possible to explicitly pass the default value.

The cases where that's not true are usually ones that are more like
C++ overloaded functions:

def next(iter):
    return iter.__next__()
def next(iter, default):
    try: return iter.__next__()
    except StopIteration: return default

You cannot have any actual object to represent the default state, for
the same reasons that you can't have __next__ return a magic value to
represent "no more values". That's why, in the proposed semantics for
an explicit late-binding syntax, I compare with *args notation, which
_can_ let you distinguish perfectly.

ChrisA


From ian.g.kelly at gmail.com  Fri Nov 20 11:29:41 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 09:29:41 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmozN9YOF-aMecR0+m2wUQncKQPaJHYw32w7nHkKaYKF_w@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>
 <CAPTjJmozN9YOF-aMecR0+m2wUQncKQPaJHYw32w7nHkKaYKF_w@mail.gmail.com>
Message-ID: <CALwzidmbq=ekjbDghcOtB0B8ND5Rn47Y8WJ4=pSt5hSi-BLK6w@mail.gmail.com>

On Fri, Nov 20, 2015 at 9:24 AM, Chris Angelico <rosuav at gmail.com> wrote:
> The cases where that's not true are usually ones that are more like
> C++ overloaded functions:
>
> def next(iter):
>     return iter.__next__()
> def next(iter, default):
>     try: return iter.__next__()
>     except StopIteration: return default

IMO the version with the default argument should have a different
name, as it is conceptually a different function.


From marko at pacujo.net  Fri Nov 20 11:31:50 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 20 Nov 2015 18:31:50 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <mailman.4.1448036255.2291.python-list@python.org>
Message-ID: <87vb8wd43t.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> On Fri, Nov 20, 2015 at 5:28 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> One could argue that you should always use a sentinel object for
>> default values. That also allows you to distinguish between omitted
>> values and default values:
>>
>>    def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
>>                flags=omitted, buttons=omitted, tablist=omitted,
>>                heading=omitted):
>>
>> but that would be rather pedantic in most circumstances.
>
> I think that would be bad design; in general, you shouldn't *need* to
> distinguish whether the value was omitted, because it should always be
> possible to explicitly pass the default value.

Consider the mutator pattern:

    def name(self, value=omitted):
        if value is omitted:
            return self._name
        self._name = value

    <URL: https://en.wikipedia.org/wiki/Mutator_method#C.2B.2B_example>


Marko


From rosuav at gmail.com  Fri Nov 20 11:36:28 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 03:36:28 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidmbq=ekjbDghcOtB0B8ND5Rn47Y8WJ4=pSt5hSi-BLK6w@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>
 <CAPTjJmozN9YOF-aMecR0+m2wUQncKQPaJHYw32w7nHkKaYKF_w@mail.gmail.com>
 <CALwzidmbq=ekjbDghcOtB0B8ND5Rn47Y8WJ4=pSt5hSi-BLK6w@mail.gmail.com>
Message-ID: <CAPTjJmpONvOJc5-cRsMdjZw76MgwsvZ7GDNszwGUX3Kf5x_4Hg@mail.gmail.com>

On Sat, Nov 21, 2015 at 3:29 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Fri, Nov 20, 2015 at 9:24 AM, Chris Angelico <rosuav at gmail.com> wrote:
>> The cases where that's not true are usually ones that are more like
>> C++ overloaded functions:
>>
>> def next(iter):
>>     return iter.__next__()
>> def next(iter, default):
>>     try: return iter.__next__()
>>     except StopIteration: return default
>
> IMO the version with the default argument should have a different
> name, as it is conceptually a different function.

Which would make it like dict.__getitem__ and dict.get, which leads to
a lot of people using dict.get() because they don't know about
subscripting. And then they mask potential errors because they're
using the version that suppresses them, since they didn't even know
about the other. Not sure that's an improvement. But I do see the
logic in the separation.

ChrisA


From rosuav at gmail.com  Fri Nov 20 11:37:03 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 03:37:03 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <87vb8wd43t.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <mailman.4.1448036255.2291.python-list@python.org>
 <87vb8wd43t.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmowWegP-ZegePmmB+NOyg_Oos+TRLk7gxvsC2fn_HBNmA@mail.gmail.com>

On Sat, Nov 21, 2015 at 3:31 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Consider the mutator pattern:
>
>     def name(self, value=omitted):
>         if value is omitted:
>             return self._name
>         self._name = value
>
>     <URL: https://en.wikipedia.org/wiki/Mutator_method#C.2B.2B_example>

That should DEFINITELY be two functions.

Or just an attribute.

ChrisA


From ian.g.kelly at gmail.com  Fri Nov 20 11:39:10 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 09:39:10 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <87vb8wd43t.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <mailman.4.1448036255.2291.python-list@python.org>
 <87vb8wd43t.fsf@elektro.pacujo.net>
Message-ID: <CALwzidkB8TL3q6-cWTM6kHBUnos3Sxk3AePV0uWM9aPO0Uxo5w@mail.gmail.com>

On Fri, Nov 20, 2015 at 9:31 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Ian Kelly <ian.g.kelly at gmail.com>:
>
>> On Fri, Nov 20, 2015 at 5:28 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> One could argue that you should always use a sentinel object for
>>> default values. That also allows you to distinguish between omitted
>>> values and default values:
>>>
>>>    def asklist(caption, data, n=omitted, rows=omitted, width=omitted,
>>>                flags=omitted, buttons=omitted, tablist=omitted,
>>>                heading=omitted):
>>>
>>> but that would be rather pedantic in most circumstances.
>>
>> I think that would be bad design; in general, you shouldn't *need* to
>> distinguish whether the value was omitted, because it should always be
>> possible to explicitly pass the default value.
>
> Consider the mutator pattern:
>
>     def name(self, value=omitted):
>         if value is omitted:
>             return self._name
>         self._name = value
>
>     <URL: https://en.wikipedia.org/wiki/Mutator_method#C.2B.2B_example>

Why would you ever want to do this in a language with properties?


From marko at pacujo.net  Fri Nov 20 11:41:42 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 20 Nov 2015 18:41:42 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <CALwzidm22e8ztCOT98ZRsPf33PAPqtjg8yiY29XQZQi47Wb3hw@mail.gmail.com>
 <CAPTjJmozN9YOF-aMecR0+m2wUQncKQPaJHYw32w7nHkKaYKF_w@mail.gmail.com>
 <mailman.7.1448037025.2291.python-list@python.org>
Message-ID: <87r3jkd3nd.fsf@elektro.pacujo.net>

Ian Kelly <ian.g.kelly at gmail.com>:

> On Fri, Nov 20, 2015 at 9:24 AM, Chris Angelico <rosuav at gmail.com> wrote:
>> The cases where that's not true are usually ones that are more like
>> C++ overloaded functions:
>>
>> def next(iter):
>>     return iter.__next__()
>> def next(iter, default):
>>     try: return iter.__next__()
>>     except StopIteration: return default
>
> IMO the version with the default argument should have a different
> name, as it is conceptually a different function.

I don't necessarily disagree, but consider this function:

   socket.create_connection(address[, timeout[, source_address]])

   <URL: https://docs.python.org/3/library/socket.html?highlight=conne
   ct#socket.create_connection>

It has been implemented:

   _GLOBAL_DEFAULT_TIMEOUT = object()

   def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
                         source_address=None):

which is somewhat inconsistent. Why not:

   def create_connection(address, timeout=None, source_address=None):

or:

   omitted = object()

   def create_connection(address, timeout=omitted,
                         source_address=omitted):

The argument for the former is that neither timeout nor source_address
can meaningfully be None. The argument for the latter is that it follows
a generic pattern that places no assumptions on the legality or
illegality of None as a value.

The chosen implementation allows:

    s.create_connection(address, source_address=None)

but not:

    s.create_connection(address, timeout=None)


Marko


From denismfmcmahon at gmail.com  Fri Nov 20 12:08:21 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Fri, 20 Nov 2015 17:08:21 -0000 (UTC)
Subject: String format - resolve placeholders names
References: <20151120145227.GB13994@arxnet.hu>
 <mailman.3.1448034840.2291.python-list@python.org>
Message-ID: <n2nk25$mns$1@dont-email.me>

On Fri, 20 Nov 2015 16:53:47 +0100, Peter Otten wrote:

> Ervin Heged?s wrote:

>> Python has a good string formatter, eg. I can do this:

>> s = "{who} likes {what}"
>> d = {'who': "Adam", 'what': "ants"}
>> s.format(**d)

>> result:
>> 'Adam likes ants'

>> Is it possible, and if yes, how to resolve the placeholders names in
>> string?

>>>> import string for item in string.Formatter().parse("{who} likes
>>>> {what}"):
> ...     print(item)
> ...
> ('', 'who', '', None)
> (' likes ', 'what', '', None)

Or even:

>>> s = "{who} likes {what}"
>>> d = {'who': "Adam", 'what': "ants"}
>>> keys = [x[1] for x in string.Formatter().parse(s)]
>>> keys
['who', 'what']

then ...

for key in keys:
    if key not in d:
        raise KeyError("Missing key '{}' in format string '{}'".format
(key, s))

-- 
Denis McMahon, denismfmcmahon at gmail.com


From denismfmcmahon at gmail.com  Fri Nov 20 12:14:21 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Fri, 20 Nov 2015 17:14:21 -0000 (UTC)
Subject: How To Create A Endles List Of Lists In Python...???
References: <n2miu8$fl4$1@ls237.t-com.hr>
Message-ID: <n2nkdd$mns$2@dont-email.me>

On Fri, 20 Nov 2015 08:43:04 +0100, HKRSS wrote:

> Thanks In Advance, Robert...;)

Just keep appending child lists to parent list:

l = []

while True:
   l.append([])

Until you run out of memory

But I think that this answer although it appears accurate to the question 
is not a solution for anything useful, because it will just use all the 
memory up. So perhaps you need to express your question in a better 
manner.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From dylan.riley at hotmail.com  Fri Nov 20 12:22:10 2015
From: dylan.riley at hotmail.com (Dylan Riley)
Date: Fri, 20 Nov 2015 09:22:10 -0800 (PST)
Subject: error help import random
Message-ID: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>

This is my fortune cookie program i wrote in python.
the problem is it will not run past the first line of input.
could someone please identify the error and explain to me why.
here is the code:

#the program silulates a fortune cookie
#the program should display one of five unique fortunes, at randon, each time its run

import random

print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
print("\n\n\tGood things come to those who wait")
input("\nPress enter to see your fortune")

fortune = random.randrange(6) + 1
print(fortune)
if fortune == 1:
    print("happy")
elif fortune == 2:
    print("horny")
elif fortune == 3:
    print("messy")
elif fortune == 4:
    print("sad")
elif fortune == 5:
    print("lool")

print("hope ypu enjoyed your fortune being told")
input("\nPress enter to exit")


many thanks in advance


From rosuav at gmail.com  Fri Nov 20 12:30:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 04:30:42 +1100
Subject: error help import random
In-Reply-To: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
Message-ID: <CAPTjJmoEgRpVxBTRZiC0hFMDtzuhFHXFQE8iD2KB8WwNft7bog@mail.gmail.com>

On Sat, Nov 21, 2015 at 4:22 AM, Dylan Riley <dylan.riley at hotmail.com> wrote:
> This is my fortune cookie program i wrote in python.
> the problem is it will not run past the first line of input.
> could someone please identify the error and explain to me why.
> here is the code:
>
> #the program silulates a fortune cookie
> #the program should display one of five unique fortunes, at randon, each time its run
>
> import random

Actually, you could help us identify the error. What happens when you
run it? Show us exactly how you invoke it and what the output is.

ChrisA


From torriem at gmail.com  Fri Nov 20 12:44:00 2015
From: torriem at gmail.com (Michael Torrie)
Date: Fri, 20 Nov 2015 10:44:00 -0700
Subject: How can I export data from a website and write the contents to
 a text file?
In-Reply-To: <2052054.MEiq1cOQgg@desk8.phess.net>
References: <9365cf2f-e9c7-4338-83b4-ce3d1d7ce1d6@googlegroups.com>
 <6e0f470b-f896-43ae-8f83-b20f22a9db8d@googlegroups.com>
 <e0edf996-9ce8-404e-b4e0-1e9a7b9af706@googlegroups.com>
 <2052054.MEiq1cOQgg@desk8.phess.net>
Message-ID: <564F5BE0.8020306@gmail.com>

On 11/19/2015 12:17 PM, Patrick Hess wrote:
> ryguy7272 wrote:
>> text_file = open("C:/Users/rshuell001/Desktop/excel/Text1.txt", "wb")
>> [...]
>> It doesn't seem like the '\n' is doing anything useful.  All the text is jumbled together.
>> [...]
>> I finally got it working.  It's like this:
>> "\r\n"
> 
> The better solution would be to open text files in actual text mode:
> 
>     open("filename", "wb")   # binary mode
>     open("filename", "w")    # text mode
> 
> In text mode, the correct line-ending characters, which will vary
> depending on the operating system, are chosen automatically.

It's not just a matter of line endings. It's a matter of text encoding
also.  This is critical in Python3 where everything is unicode and
encoding is essential.  You have to to use the text mode when writing
files here, and it's also a good idea to specify what encoding you wish
to write with (UTF-8 is a good default).



From __peter__ at web.de  Fri Nov 20 12:57:44 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 20 Nov 2015 18:57:44 +0100
Subject: error help import random
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
Message-ID: <n2nmup$j2n$1@ger.gmane.org>

Dylan Riley wrote:

> This is my fortune cookie program i wrote in python.
> the problem is it will not run past the first line of input.
> could someone please identify the error and explain to me why.
> here is the code:
> 
> #the program silulates a fortune cookie
> #the program should display one of five unique fortunes, at randon, each
> #time its run
> 
> import random
> 
> print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
> print("\n\n\tGood things come to those who wait")
> input("\nPress enter to see your fortune")
> 
> fortune = random.randrange(6) + 1
> print(fortune)
> if fortune == 1:
>     print("happy")
> elif fortune == 2:
>     print("horny")
> elif fortune == 3:
>     print("messy")
> elif fortune == 4:
>     print("sad")
> elif fortune == 5:
>     print("lool")
> 
> print("hope ypu enjoyed your fortune being told")
> input("\nPress enter to exit")
> 
> 
> many thanks in advance

Make sure that you run your code with Python 3, not Python 2.



From w.g.sneddon at gmail.com  Fri Nov 20 13:01:02 2015
From: w.g.sneddon at gmail.com (bSneddon)
Date: Fri, 20 Nov 2015 10:01:02 -0800 (PST)
Subject: Dabbling in web development
In-Reply-To: <mailman.500.1447978111.16136.python-list@python.org>
References: <2a5d3947-a49a-48f8-bc4c-7d126d3d6fef@googlegroups.com>
 <mailman.500.1447978111.16136.python-list@python.org>
Message-ID: <af6452b5-22a8-4ed6-8389-6ca90af54b3b@googlegroups.com>

Thanks all!


From ian.g.kelly at gmail.com  Fri Nov 20 13:10:49 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 11:10:49 -0700
Subject: error help import random
In-Reply-To: <n2nmup$j2n$1@ger.gmane.org>
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
 <n2nmup$j2n$1@ger.gmane.org>
Message-ID: <CALwzid=_-rSxidAviakxrRZtWzZuA7x=q4xgfkmuchmVSkQj+g@mail.gmail.com>

On Fri, Nov 20, 2015 at 10:57 AM, Peter Otten <__peter__ at web.de> wrote:
> Dylan Riley wrote:
>
>> input("\nPress enter to see your fortune")
>
> Make sure that you run your code with Python 3, not Python 2.

Or if you must use Python 2, use raw_input() instead of input().

>> fortune = random.randrange(6) + 1

Also, you have an off-by-one error here. randrange(6) will give you an
integer between 0 and 5, inclusive (a total of 6 possible values).
Adding 1 will then result in an integer between 1 and 6, inclusive,
but you don't have a case for a value of 6.


From robert.bralic at si.t-com.hr  Fri Nov 20 13:16:06 2015
From: robert.bralic at si.t-com.hr (robert.bralic at si.t-com.hr)
Date: Fri, 20 Nov 2015 10:16:06 -0800 (PST)
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <n2nkdd$mns$2@dont-email.me>
References: <n2miu8$fl4$1@ls237.t-com.hr> <n2nkdd$mns$2@dont-email.me>
Message-ID: <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>

Dana petak, 20. studenoga 2015. u 18:16:52 UTC+1, korisnik Denis McMahon napisao je:
> On Fri, 20 Nov 2015 08:43:04 +0100, HKRSS wrote:
> 
> > Thanks In Advance, Robert...;)
> 
> Just keep appending child lists to parent list:
> 
> l = []
> 
> while True:
>    l.append([])
> 
> Until you run out of memory
> 
> But I think that this answer although it appears accurate to the question 
> is not a solution for anything useful, because it will just use all the 
> memory up. So perhaps you need to express your question in a better 
> manner.
> 
> -- 
> Denis McMahon, denismfmcmahon at gmail.com

I Think That LISP Is Only Solution, I Wil Give Up Frpm Python...

Thanks, Robert...;)


From mr.eightnoteight at gmail.com  Fri Nov 20 13:28:20 2015
From: mr.eightnoteight at gmail.com (srinivas devaki)
Date: Fri, 20 Nov 2015 23:58:20 +0530
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <CAPTjJmpJoktL=OdaCOw3KGukxUKBu+nW+cUFvwv47KCczAKXsg@mail.gmail.com>
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr> <564F1AC0.5040106@shopzeus.com>
 <CAPTjJmpJoktL=OdaCOw3KGukxUKBu+nW+cUFvwv47KCczAKXsg@mail.gmail.com>
Message-ID: <CACs7g=B0AyWyQ61FU+7V=r2P1t1A5d90DiQ0tyJAv=yaBAUwzQ@mail.gmail.com>

On Fri, Nov 20, 2015 at 6:39 PM, Chris Angelico <rosuav at gmail.com> wrote:
> My crystal ball suggests that defaultdict(list) might be useful here.
>
> ChrisA

I used something similar to this for some problem in hackerrank,
anyway i think this is what you want.

class defaultlist(object):
    def __init__(self, factory, data=None):
        self.factory = factory
        self.list = []
        self.data = data

    def __getitem__(self, x):
        if x >= len(self.list):
            self.list.extend([self.factory() for _ in
range(len(self.list), x + 1)])
        return self.list[x]

    def __repr__(self):
        return str(self)

    def __str__(self):
        if len(self.list) == 0:
            return '(' + str(self.data) +  ')[...]'
        return ''.join(['(', str(self.data), ')['] + map(str,
self.list) + [', ...]'])


    def __setitem__(self, x, v):
        if x >= len(self.list):
            self.list.extend([self.factory() for _ in
range(len(self.list), x + 1)])
        self.list[x] = v

def main():
    factory = lambda: defaultlist(factory)
    list_of_lists = defaultlist(factory)
    print (list_of_lists[0])
    list_of_lists[0][10].data = 20
    print (list_of_lists[0])


main()

Gist: https://gist.github.com/c0c2ee1e7c6535ef8c3d


From ian.g.kelly at gmail.com  Fri Nov 20 13:29:11 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Fri, 20 Nov 2015 11:29:11 -0700
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
References: <n2miu8$fl4$1@ls237.t-com.hr> <n2nkdd$mns$2@dont-email.me>
 <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
Message-ID: <CALwzidmfM9e1+wTGyjMxAsh0x_UOgLsu9KP8FdqEu4795F5w1g@mail.gmail.com>

On Fri, Nov 20, 2015 at 11:16 AM,  <robert.bralic at si.t-com.hr> wrote:
> Dana petak, 20. studenoga 2015. u 18:16:52 UTC+1, korisnik Denis McMahon napisao je:
>> On Fri, 20 Nov 2015 08:43:04 +0100, HKRSS wrote:
>>
>> > Thanks In Advance, Robert...;)
>>
>> Just keep appending child lists to parent list:
>>
>> l = []
>>
>> while True:
>>    l.append([])
>>
>> Until you run out of memory
>>
>> But I think that this answer although it appears accurate to the question
>> is not a solution for anything useful, because it will just use all the
>> memory up. So perhaps you need to express your question in a better
>> manner.
>>
>> --
>> Denis McMahon, denismfmcmahon at gmail.com
>
> I Think That LISP Is Only Solution, I Wil Give Up Frpm Python...

Nagy and Chris gave you two different perfectly good solutions for Python.


From rosuav at gmail.com  Fri Nov 20 13:30:23 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 05:30:23 +1100
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
References: <n2miu8$fl4$1@ls237.t-com.hr> <n2nkdd$mns$2@dont-email.me>
 <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
Message-ID: <CAPTjJmqd71QNgVjQEidf_TzC9tuWZa63Ec66R1A9dSt1ru+LkQ@mail.gmail.com>

On Sat, Nov 21, 2015 at 5:16 AM,  <robert.bralic at si.t-com.hr> wrote:
> I Think That LISP Is Only Solution, I Wil Give Up Frpm Python...

Capital Letters For The Win. You Should Consider Talking In German.

ChrisA


From mr.eightnoteight at gmail.com  Fri Nov 20 13:35:41 2015
From: mr.eightnoteight at gmail.com (srinivas devaki)
Date: Sat, 21 Nov 2015 00:05:41 +0530
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <CACs7g=B0AyWyQ61FU+7V=r2P1t1A5d90DiQ0tyJAv=yaBAUwzQ@mail.gmail.com>
References: <n2miu8$fl4$1@ls237.t-com.hr>
 <mailman.510.1448009596.16136.python-list@python.org>
 <n2mugp$kt1$1@ls237.t-com.hr> <564F1AC0.5040106@shopzeus.com>
 <CAPTjJmpJoktL=OdaCOw3KGukxUKBu+nW+cUFvwv47KCczAKXsg@mail.gmail.com>
 <CACs7g=B0AyWyQ61FU+7V=r2P1t1A5d90DiQ0tyJAv=yaBAUwzQ@mail.gmail.com>
Message-ID: <CACs7g=DSsTwHx0nO0YVmiCdZSyhq3fL3NZAMn9Dz55DVNrkWkg@mail.gmail.com>

On Fri, Nov 20, 2015 at 11:58 PM, srinivas devaki
<mr.eightnoteight at gmail.com> wrote:
>     def __str__(self):
>         if len(self.list) == 0:
>             return '(' + str(self.data) +  ')[...]'
>         return ''.join(['(', str(self.data), ')['] + map(str, self.list) + [', ...]'])
> ...
> Gist: https://gist.github.com/c0c2ee1e7c6535ef8c3d

uhh, there is an error in representing it, the code should be

def __str__(self):
    if len(self.list) == 0:
        return '(' + str(self.data) +  ')[...]'
    return ''.join(['(', str(self.data), ')[', ', '.join(map(str,
self.list)), ', ...]'])

Output:
(None)[...]
(None)[(None)[...], (None)[...], (None)[...], (20)[...], ...]


ps: code is updated in gist.


From sohcahtoa82 at gmail.com  Fri Nov 20 14:26:33 2015
From: sohcahtoa82 at gmail.com (sohcahtoa82 at gmail.com)
Date: Fri, 20 Nov 2015 11:26:33 -0800 (PST)
Subject: How To Create A Endles List Of Lists In Python...???
In-Reply-To: <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
References: <n2miu8$fl4$1@ls237.t-com.hr> <n2nkdd$mns$2@dont-email.me>
 <c83d0ce8-9855-4afa-9efe-f9bfe9b78931@googlegroups.com>
Message-ID: <dcbd5076-7c69-4e29-9db7-b025890354eb@googlegroups.com>

On Friday, November 20, 2015 at 10:16:34 AM UTC-8, robert... at si.t-com.hr wrote:
> Dana petak, 20. studenoga 2015. u 18:16:52 UTC+1, korisnik Denis McMahon napisao je:
> > On Fri, 20 Nov 2015 08:43:04 +0100, HKRSS wrote:
> > 
> > > Thanks In Advance, Robert...;)
> > 
> > Just keep appending child lists to parent list:
> > 
> > l = []
> > 
> > while True:
> >    l.append([])
> > 
> > Until you run out of memory
> > 
> > But I think that this answer although it appears accurate to the question 
> > is not a solution for anything useful, because it will just use all the 
> > memory up. So perhaps you need to express your question in a better 
> > manner.
> > 
> > -- 
> > Denis McMahon, denismfmcmahon at gmail.com
> 
> I Think That LISP Is Only Solution, I Wil Give Up Frpm Python...
> 
> Thanks, Robert...;)

Is There A Reason You're Starting Every Word With A Capital Letter?

I mean, really, you're going out of your way and expending extra effort to type incorrectly.


From airween at gmail.com  Fri Nov 20 14:34:10 2015
From: airween at gmail.com (Ervin =?utf-8?Q?Heged=C3=BCs?=)
Date: Fri, 20 Nov 2015 20:34:10 +0100
Subject: String format - resolve placeholders names
In-Reply-To: <n2nfme$hfn$1@ger.gmane.org>
References: <20151120145227.GB13994@arxnet.hu>
 <n2nfme$hfn$1@ger.gmane.org>
Message-ID: <20151120193410.GA29560@arxnet.hu>

Hi Peter,

On Fri, Nov 20, 2015 at 04:53:47PM +0100, Peter Otten wrote:
> Ervin Heged?s wrote:
> 
> > Python has a good string formatter, eg. I can do this:
> > 
> > s = "{who} likes {what}"
> > d = {'who': "Adam", 'what': "ants"}
> > s.format(**d)
> > 
> > result:
> > 'Adam likes ants'
> > 
> > Is it possible, and if yes, how to resolve the placeholders names
> > in string?
> 
> >>> import string
> >>> for item in string.Formatter().parse("{who} likes {what}"):
> ...     print(item)
> ... 
> ('', 'who', '', None)
> (' likes ', 'what', '', None)

nice solution, thanks,


a.
 

-- 
I ? UTF-8


From airween at gmail.com  Fri Nov 20 14:36:31 2015
From: airween at gmail.com (Ervin =?utf-8?Q?Heged=C3=BCs?=)
Date: Fri, 20 Nov 2015 20:36:31 +0100
Subject: String format - resolve placeholders names
In-Reply-To: <n2nk25$mns$1@dont-email.me>
References: <20151120145227.GB13994@arxnet.hu>
 <mailman.3.1448034840.2291.python-list@python.org>
 <n2nk25$mns$1@dont-email.me>
Message-ID: <20151120193631.GB29560@arxnet.hu>

Hi Denis,

On Fri, Nov 20, 2015 at 05:08:21PM -0000, Denis McMahon wrote:
> On Fri, 20 Nov 2015 16:53:47 +0100, Peter Otten wrote:
> 
> > Ervin Heged?s wrote:
> 
> >> Python has a good string formatter, eg. I can do this:
> 
 
> Or even:
> 
> >>> s = "{who} likes {what}"
> >>> d = {'who': "Adam", 'what': "ants"}
> >>> keys = [x[1] for x in string.Formatter().parse(s)]
> >>> keys
> ['who', 'what']
> 
> then ...
> 
> for key in keys:
>     if key not in d:
>         raise KeyError("Missing key '{}' in format string '{}'".format
> (key, s))

well, I think I'm very satisfied - I got better and more better
solutions :).


Thanks for all, folks:

a.
 

-- 
I ? UTF-8


From tjreedy at udel.edu  Fri Nov 20 15:15:42 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Fri, 20 Nov 2015 15:15:42 -0500
Subject: error help import random
In-Reply-To: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
Message-ID: <n2nv1l$p87$1@ger.gmane.org>

On 11/20/2015 12:22 PM, Dylan Riley wrote:
> This is my fortune cookie program i wrote in python.
> the problem is it will not run past the first line of input.
> could someone please identify the error and explain to me why.
> here is the code:
>
> #the program silulates a fortune cookie
> #the program should display one of five unique fortunes, at randon, each time its run
>
> import random
>
> print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
> print("\n\n\tGood things come to those who wait")
> input("\nPress enter to see your fortune")
>
> fortune = random.randrange(6) + 1
> print(fortune)
> if fortune == 1:
>      print("happy")
> elif fortune == 2:
>      print("horny")
> elif fortune == 3:
>      print("messy")
> elif fortune == 4:
>      print("sad")
> elif fortune == 5:
>      print("lool")

Use a dict instead of if-elif.

i = random.randrange(6)
fortunes = {0:'happy', 1:'horny', 2:'messy',
             3:'sad', 4:'lool', 5:'buggy'}
print(i, fortunes[i])

> print("hope ypu enjoyed your fortune being told")
> input("\nPress enter to exit")


-- 
Terry Jan Reedy



From stephane at wirtel.be  Fri Nov 20 17:14:57 2015
From: stephane at wirtel.be (Stephane Wirtel)
Date: Fri, 20 Nov 2015 23:14:57 +0100
Subject: Mapping between python packages and distro packages?
In-Reply-To: <85vb90c4fv.fsf@benfinney.id.au>
References: <20151118032903.GA8040@sg1>
 <85vb90c4fv.fsf@benfinney.id.au>
Message-ID: <20151120221457.GA7590@sg1>

Hi Ben,

sorry for my late reply, just forgotten to reply :/ really sorry

in fact, I would like to have a database where I want the requests
library, I will get the python-requests for debian/ubuntu and the right
package for the yum installer.

I have an other solution, but I don't like it because I risk to break
the linux distribution (the target) and use the wheel package.

On 11/18, Ben Finney wrote:
> Stephane Wirtel <stephane at wirtel.be> writes:
> 
> > Do you know if there is a library to match a python package (from PyPI)
> > and find the right debian/redhat packages ?
> 
> What would count as ?the right package??
> 
> Do you mean ?the package that has that PyPI distribution URL in its
> ?debian/watch? configuration??
> 
> Do you mean ?the package that names that PyPI distribution in its
> ?debian/copyright? ?Source? field??
> 
> Or something else?
> 
> The answers will differ depending on exactly what question is being
> asked of the data.
> 
> If you can define exactly what query you want to perform, perhaps a
> solution can be offered.
> 
> -- 
>  \     ?The Vatican is not a state.? a state must have territory. This |
>   `\         is a palace with gardens, about as big as an average golf |
> _o__)                         course.? ?Geoffrey Robertson, 2010-09-18 |
> Ben Finney
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list

-- 
St?phane Wirtel - http://wirtel.be - @matrixise


From stephane at wirtel.be  Fri Nov 20 17:15:50 2015
From: stephane at wirtel.be (Stephane Wirtel)
Date: Fri, 20 Nov 2015 23:15:50 +0100
Subject: Mapping between python packages and distro packages?
In-Reply-To: <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>
References: <20151118032903.GA8040@sg1> <85vb90c4fv.fsf@benfinney.id.au>
 <CAPTjJmotkP4LPy90TBKSvC5b6ugptY4+5wkRxMp1ZvcqK3S=cQ@mail.gmail.com>
Message-ID: <20151120221550.GB7590@sg1>

> I don't know how the program would detect it, but I'd be thinking "the
> one where 'sudo apt-get install PACKAGENAME' gets the same code that
> 'pip install THING' gets". In a lot of cases, PACKAGENAME will simply
> be python-THING or python3-THING, eg python3-sqlalchemy,
> python3-scipy, python3-bs4; as a human, that's what I'd try first. But
> having a program recognize this would be hugely beneficial.
+1

-- 
St?phane Wirtel - http://wirtel.be - @matrixise


From rgaddi at technologyhighland.invalid  Fri Nov 20 18:03:26 2015
From: rgaddi at technologyhighland.invalid (Rob Gaddi)
Date: Fri, 20 Nov 2015 23:03:26 -0000 (UTC)
Subject: error help import random
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
 <mailman.21.1448050562.2291.python-list@python.org>
Message-ID: <n2o8ru$m03$1@dont-email.me>

On Fri, 20 Nov 2015 15:15:42 -0500, Terry Reedy wrote:

> On 11/20/2015 12:22 PM, Dylan Riley wrote:
>> This is my fortune cookie program i wrote in python.
>> the problem is it will not run past the first line of input.
>> could someone please identify the error and explain to me why.
>> here is the code:
>>
>> #the program silulates a fortune cookie #the program should display one
>> of five unique fortunes, at randon, each time its run
>>
>> import random
>>
>> print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
>> print("\n\n\tGood things come to those who wait")
>> input("\nPress enter to see your fortune")
>>
>> fortune = random.randrange(6) + 1 print(fortune)
>> if fortune == 1:
>>      print("happy")
>> elif fortune == 2:
>>      print("horny")
>> elif fortune == 3:
>>      print("messy")
>> elif fortune == 4:
>>      print("sad")
>> elif fortune == 5:
>>      print("lool")
> 
> Use a dict instead of if-elif.
> 
> i = random.randrange(6)
> fortunes = {0:'happy', 1:'horny', 2:'messy',
>              3:'sad', 4:'lool', 5:'buggy'}
> print(i, fortunes[i])
> 

Or a list/tuple, which saves in typing, memory, and access time.

  fortunes = ('happy', 'horny', 'messy', 'sad', 'lool', 'buggy')
  i = random.randrange(len(fortunes))
  print(i, fortunes[i])

Or to be lazier still, just use random.choice

  fortunes = ('happy', 'horny', 'messy', 'sad', 'lool', 'buggy')
  print(random.choice(fortunes))

None of which actually addresses the OP's issue with input(), but it's 
nice to get the back half clean as well.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.


From Seymore4Head at Hotmail.invalid  Fri Nov 20 18:05:09 2015
From: Seymore4Head at Hotmail.invalid (Seymore4Head)
Date: Fri, 20 Nov 2015 18:05:09 -0500
Subject: error help import random
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
Message-ID: <mn9v4btss3epg7ijle8b8kg2nnqbkip4el@4ax.com>

On Fri, 20 Nov 2015 09:22:10 -0800 (PST), Dylan Riley
<dylan.riley at hotmail.com> wrote:

>This is my fortune cookie program i wrote in python.
>the problem is it will not run past the first line of input.
>could someone please identify the error and explain to me why.
>here is the code:
>
>#the program silulates a fortune cookie
>#the program should display one of five unique fortunes, at randon, each time its run
>
>import random
>
A problem I used to have is that if you have a file called random.py
in the folder when you try to import random, it caused an error.

>print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
>print("\n\n\tGood things come to those who wait")
>input("\nPress enter to see your fortune")
>
>fortune = random.randrange(6) + 1
>print(fortune)
>if fortune == 1:
>    print("happy")
>elif fortune == 2:
>    print("horny")
>elif fortune == 3:
>    print("messy")
>elif fortune == 4:
>    print("sad")
>elif fortune == 5:
>    print("lool")
>
>print("hope ypu enjoyed your fortune being told")
>input("\nPress enter to exit")
>
>
>many thanks in advance


From ben+python at benfinney.id.au  Fri Nov 20 21:34:20 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 21 Nov 2015 13:34:20 +1100
Subject: Mapping between python packages and distro packages?
References: <20151118032903.GA8040@sg1> <85vb90c4fv.fsf@benfinney.id.au>
 <20151120221457.GA7590@sg1>
Message-ID: <85d1v4cc7n.fsf@benfinney.id.au>

Stephane Wirtel <stephane at wirtel.be> writes:

> in fact, I would like to have a database where I want the requests
> library, I will get the python-requests for debian/ubuntu and the
> right package for the yum installer.

Okay. That's a pretty simple technical problem (a simple relation
between PyPI distribution name, GNU+Linux operating system name, and
package name).

Of course, *populating* that database, *verifying* the ambiguous inputs,
and *maintaining* that database into the future, are all social
problems. You'll probably need an organised group of people to address
it.

I'm not aware of any sufficiently motivated group of people to put in
the ongoing effort to provide what you want.

(Another social problem is convincing people not to top-post, but
instead to reply interleaved and trim irrelevant quoted material
<URL:https://en.wikipedia.org/wiki/Posting_style#Interleaved_style>.)

-- 
 \       ?Anyone who puts a small gloss on [a] fundamental technology, |
  `\          calls it proprietary, and then tries to keep others from |
_o__)           building on it, is a thief.? ?Tim O'Reilly, 2000-01-25 |
Ben Finney



From dylan.riley at hotmail.com  Fri Nov 20 22:26:34 2015
From: dylan.riley at hotmail.com (Dylan Riley)
Date: Fri, 20 Nov 2015 19:26:34 -0800 (PST)
Subject: error help import random
In-Reply-To: <n2o8ru$m03$1@dont-email.me>
References: <8b0ec311-ab7f-429d-877f-d205ad6008d9@googlegroups.com>
 <mailman.21.1448050562.2291.python-list@python.org>
 <n2o8ru$m03$1@dont-email.me>
Message-ID: <66756cd4-d3ef-42db-8471-8475ed540a27@googlegroups.com>

On Friday, November 20, 2015 at 11:06:05 PM UTC, Rob Gaddi wrote:
> On Fri, 20 Nov 2015 15:15:42 -0500, Terry Reedy wrote:
> 
> > On 11/20/2015 12:22 PM, Dylan Riley wrote:
> >> This is my fortune cookie program i wrote in python.
> >> the problem is it will not run past the first line of input.
> >> could someone please identify the error and explain to me why.
> >> here is the code:
> >>
> >> #the program silulates a fortune cookie #the program should display one
> >> of five unique fortunes, at randon, each time its run
> >>
> >> import random
> >>
> >> print("  \\ \\ \\ \\ DYLANS FORTUNE COOKIE \\ \\ \\ ")
> >> print("\n\n\tGood things come to those who wait")
> >> input("\nPress enter to see your fortune")
> >>
> >> fortune = random.randrange(6) + 1 print(fortune)
> >> if fortune == 1:
> >>      print("happy")
> >> elif fortune == 2:
> >>      print("horny")
> >> elif fortune == 3:
> >>      print("messy")
> >> elif fortune == 4:
> >>      print("sad")
> >> elif fortune == 5:
> >>      print("lool")
> > 
> > Use a dict instead of if-elif.
> > 
> > i = random.randrange(6)
> > fortunes = {0:'happy', 1:'horny', 2:'messy',
> >              3:'sad', 4:'lool', 5:'buggy'}
> > print(i, fortunes[i])
> > 
> 
> Or a list/tuple, which saves in typing, memory, and access time.
> 
>   fortunes = ('happy', 'horny', 'messy', 'sad', 'lool', 'buggy')
>   i = random.randrange(len(fortunes))
>   print(i, fortunes[i])
> 
> Or to be lazier still, just use random.choice
> 
>   fortunes = ('happy', 'horny', 'messy', 'sad', 'lool', 'buggy')
>   print(random.choice(fortunes))
> 
> None of which actually addresses the OP's issue with input(), but it's 
> nice to get the back half clean as well.
> 
> -- 
> Rob Gaddi, Highland Technology -- www.highlandtechnology.com
> Email address domain is currently out of order.  See above to fix.

very nice i like the way you code. i managed to solve the problem it was because i wasnt using raw_input however i updated to python 3 so the original now works. many thanks anyway


From dylan.riley at hotmail.com  Fri Nov 20 22:30:02 2015
From: dylan.riley at hotmail.com (Dylan Riley)
Date: Fri, 20 Nov 2015 19:30:02 -0800 (PST)
Subject: anyone tell me why my program will not run?
Message-ID: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>

i am learning python and was tasked with making a program that flips a coin 100 times and then tells you
the number of heads and tails.

I have done so coming up with this piece of work but it doesnt run can anyone help me out?

#This is credited to dylan

print(" \\ \\ \\ \\ \\ \\ \\ \\ D FLIPS \\ \\ \\ \\ \\ \\ \\ \\")
print("\n\nThis is D's coin flipper program. You get 100 flips. \n\t LETS SEE HOW LUCKY YOU ARE")
input("Press enter")

import random

heads = int("1")
tails = int("2")
flips = 100
headscount = 0
tailscount = 0

while flips != 0:
    flips -= 1

result = random.randint(heads, tails)
if result = heads:
    headscount += 1
else:
    tailscount += 1


print(headscount, tailscount)

input("press enter to exit")


From joel.goldstick at gmail.com  Fri Nov 20 22:39:22 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Fri, 20 Nov 2015 22:39:22 -0500
Subject: anyone tell me why my program will not run?
In-Reply-To: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <CAPM-O+wVatwuXD=h614JNNgiJuxoemRj2PfU3Md2YwUXK8go6Q@mail.gmail.com>

On Fri, Nov 20, 2015 at 10:30 PM, Dylan Riley <dylan.riley at hotmail.com>
wrote:

> i am learning python and was tasked with making a program that flips a
> coin 100 times and then tells you
> the number of heads and tails.
>
> I have done so coming up with this piece of work but it doesnt run can
> anyone help me out?
>
> #This is credited to dylan
>
> print(" \\ \\ \\ \\ \\ \\ \\ \\ D FLIPS \\ \\ \\ \\ \\ \\ \\ \\")
> print("\n\nThis is D's coin flipper program. You get 100 flips. \n\t LETS
> SEE HOW LUCKY YOU ARE")
> input("Press enter")
>
> import random
>
> heads = int("1")
> tails = int("2")
> flips = 100
> headscount = 0
> tailscount = 0
>
> while flips != 0:
>     flips -= 1
>
> shouldn't this below be in the while loop?


> result = random.randint(heads, tails)
> if result = heads:
>     headscount += 1
> else:
>     tailscount += 1
>
>
> up to here


> print(headscount, tailscount)
>
> input("press enter to exit")
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From rosuav at gmail.com  Sat Nov 21 00:50:39 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 16:50:39 +1100
Subject: anyone tell me why my program will not run?
In-Reply-To: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <CAPTjJmqXFwtjGEcsRVaobywtR2tOK=LR_bHGa=A1uF30dUoYHQ@mail.gmail.com>

On Sat, Nov 21, 2015 at 2:30 PM, Dylan Riley <dylan.riley at hotmail.com> wrote:
> I have done so coming up with this piece of work but it doesnt run can anyone help me out?
>

Please, please, try to help us out here! What does it mean to "not
run"? Does it run and give an exception? Does it run to completion but
give no output? Do you type "python somefile.py" and get back an error
from the system? What?

ChrisA


From gengyangcai at gmail.com  Sat Nov 21 01:54:37 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Fri, 20 Nov 2015 22:54:37 -0800 (PST)
Subject: Traceback error
Message-ID: <e5d80196-61c5-44d9-bec8-dc563d58fa6a@googlegroups.com>

This is a piece of code about comparators :


j# Assign True or False as appropriate on the lines below!

# Set this to True if 17 < 328 or to False if it is not.
bool_one = 17 < 328   # We did this one for you!

# Set this to True if 100 == (2 * 50) or to False otherwise.
bool_two = 100 == (2 * 50)

# Set this to True if 19 <= 19 or to False if it is not.
bool_three = 19 <= 19

# Set this to True if -22 >= -18 or to False if it is not.
bool_four = -22 >= -18

# Set this to True if 99 != (98 + 1) or to False otherwise.
bool_five = 99 != (98 + 1)


When I tried to run it, this is the error I got : 

Traceback (most recent call last):
  File "python", line 1, in <module>
NameError: name 'j' is not defined


Any ideas how to debug this ?

Thanks a lot!

Appreciate it

Cai Gengyang


From frank at chagford.com  Sat Nov 21 02:26:06 2015
From: frank at chagford.com (Frank Millman)
Date: Sat, 21 Nov 2015 09:26:06 +0200
Subject: Traceback error
In-Reply-To: <e5d80196-61c5-44d9-bec8-dc563d58fa6a@googlegroups.com>
References: <e5d80196-61c5-44d9-bec8-dc563d58fa6a@googlegroups.com>
Message-ID: <n2p6ai$tqq$1@ger.gmane.org>

"Cai Gengyang"  wrote in message 
news:e5d80196-61c5-44d9-bec8-dc563d58fa6a at googlegroups.com...

> This is a piece of code about comparators :


> j# Assign True or False as appropriate on the lines below!

[snip rest of code]

> When I tried to run it, this is the error I got :

> Traceback (most recent call last):
>   File "python", line 1, in <module>
> NameError: name 'j' is not defined


> Any ideas how to debug this ?


It looks to me as if the error is right there on the first line. What is 
that 'j' doing there? It looks like a typo.

HTH

Frank Millman




From dieter at handshake.de  Sat Nov 21 02:26:44 2015
From: dieter at handshake.de (dieter)
Date: Sat, 21 Nov 2015 08:26:44 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.508.1448005763.16136.python-list@python.org>
 <lf5bnapm4xa.fsf@ling.helsinki.fi>
Message-ID: <87egfjhky3.fsf@handshake.de>

Jussi Piitulainen <harvesting at is.invalid> writes:
> dieter writes:
>> Chris Angelico writes:
>>
>>> IMO it's controversial mainly because there's an easy and obvious
>>> syntax for early binding, but late binding doesn't have syntactic
>>> support, and all the options are imperfect.
>>
>> I do not think that we should get additional syntax for lately bound
>> default values. It would explicitely introduce the concepts early
>> versus late binding which are likely difficult to understand by many
>> users.
>
> I'm confused by the term. I don't like it one bit.
>
> "Early binding" of a default value seems to mean that the expression
> that produces the default value of a function parameter is evaluated
> when the function is defined. "Late binding" seems to mean that the
> expression is evaluated when the function is called.
>
> In both cases the actual binding of the parameter to the value (either
> the default or an actual argument) is established when the function is
> called. Several different bindings of that same parameter to different
> values can hold simultaneously, so the *binding* has to be conceptually
> "late". Because recursion.

Conventionally, "binding" is the association of a "value" with a "name".

In this sense, you can call "early binding" the current Python behavior
with respect to default parameters: the expression is evaluated into
a "value" at function definition time and bound to the parameter name.
A later call may rebind the parameter name (if it provides its own value).

In the case of "late binding", the function definition would also
bind at function definition time the "name"
to something (but not a "value"): an expression,
maybe together with some binding. This expression would then
be evaluated at a later time (and we only then get the typical
binding of a "name" to a "value").


> Why isn't the evaluation of the default expression called evaluation?

I do not mind if you prefer to use the term "evaluation"
instead of "binding". Nothing important in my previous message
would be changed by the term exchange: you must specify how (and when)
the variables referenced in the expression get their values. And
this will give new difficulties - more serious than
Python's current handling of default parameters.




From dieter at handshake.de  Sat Nov 21 02:31:13 2015
From: dieter at handshake.de (dieter)
Date: Sat, 21 Nov 2015 08:31:13 +0100
Subject: Traceback error
References: <e5d80196-61c5-44d9-bec8-dc563d58fa6a@googlegroups.com>
Message-ID: <87a8q7hkqm.fsf@handshake.de>

Cai Gengyang <gengyangcai at gmail.com> writes:

> This is a piece of code about comparators :
> j# Assign True or False as appropriate on the lines below!
> ...
> When I tried to run it, this is the error I got : 
>
> Traceback (most recent call last):
>   File "python", line 1, in <module>
> NameError: name 'j' is not defined

The error information is very precise: in your line 1, you have:

    j# Assign True or False as appropriate on the lines below!

The "j" before the comment ("#...") is what causes the problem.
Likely, you did not want it there.



From gengyangcai at gmail.com  Sat Nov 21 02:33:06 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Fri, 20 Nov 2015 23:33:06 -0800 (PST)
Subject: Traceback error
In-Reply-To: <mailman.29.1448090792.2291.python-list@python.org>
References: <e5d80196-61c5-44d9-bec8-dc563d58fa6a@googlegroups.com>
 <mailman.29.1448090792.2291.python-list@python.org>
Message-ID: <3e2577a5-a6e5-48b1-ae6a-6496403db7d0@googlegroups.com>

Right ... I removed the 'j' and the code works now. I must have accidentally put it in , forgot about it and thought that it was part of the original code when it shouldn't have been there in the first place.

Thanks !


On Saturday, November 21, 2015 at 3:27:02 PM UTC+8, Frank Millman wrote:
> "Cai Gengyang"  wrote in message 
> news:e5d80196-61c5-44d9-bec8-dc563d58fa6a at googlegroups.com...
> 
> > This is a piece of code about comparators :
> 
> 
> > j# Assign True or False as appropriate on the lines below!
> 
> [snip rest of code]
> 
> > When I tried to run it, this is the error I got :
> 
> > Traceback (most recent call last):
> >   File "python", line 1, in <module>
> > NameError: name 'j' is not defined
> 
> 
> > Any ideas how to debug this ?
> 
> 
> It looks to me as if the error is right there on the first line. What is 
> that 'j' doing there? It looks like a typo.
> 
> HTH
> 
> Frank Millman


From toddrjen at gmail.com  Sat Nov 21 03:38:01 2015
From: toddrjen at gmail.com (Todd)
Date: Sat, 21 Nov 2015 09:38:01 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
Message-ID: <CAFpSVpJ1MOaH=V9wxzgzkRzrSG0YoKQk7WQ4Fo1K5fd0QLPBuQ@mail.gmail.com>

On Nov 19, 2015 20:48, "Chris Angelico" <rosuav at gmail.com> wrote:
>
> On Fri, Nov 20, 2015 at 5:42 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> > BartC on the other hand is just complaining about an aspect of Python
> > that is legitimately controversial.
>
> IMO it's controversial mainly because there's an easy and obvious
> syntax for early binding, but late binding doesn't have syntactic
> support, and all the options are imperfect. Consider:
>
> def late1(x=None):
>     """Terse but buggy"""
>     do_stuff_with(x or [])
>
> def late2(x=None):
>     """Not bad but has an extra line for each default. Also, can't take
None."""
>     if x is None: x = []
>     do_stuff_with(x)
>
> _SENTINEL = object()
> def late3(x=_SENTINEL):
>     """Has the same global-pollution problem you get when you
>     try to construct early binding from late; you can share the
>     sentinel among multiple args, even multiple funcs, though"""
>     if x is _SENTINEL: x = []
>     do_stuff_with(x)
>
> def late4(x=object()):
>     """Depends on its own name remaining bound in its scope,
>     and will break if you change argument order"""
>     if x is late4.__defaults__[0]: x = []
>     do_stuff_with(x)
>
> And there might be other techniques, too. They all share one important
> flaw, too: When you ask for help about the function, you can't see
> what the default really is. All you see is:
>
> late1(x=None)
> late3(x=<object object at 0x7f7a80b3a080>)
>
> In the first two cases, it's not too bad; you can specify a timeout as
> either a number or as None, and if it's None (the default), the
> timeout is three times the currently estimated round trip time. No
> problem. But how would you implement something like next() in pure
> Python? If you provide _any second argument at all_, it returns that
> instead of raising StopIteration. The ONLY way that I can think of is
> to use *args notation:
>
> def next(iterator, *default):
>     try:
>         return iterator.__next__()
>     except StopIteration:
>         if default: return default[0]
>         raise
>
> And while that isn't TOO bad for just one argument, it scales poorly:
>
> def foo(fixed_arg, *args):
>     """Foo the fixed_arg against the spam mapping, the
>     ham sequence, and the jam file."""
>     args.reverse()
>     spam = args.pop() if args else {}
>     ham = args.pop() if args else []
>     jam = args.pop() if args else open("jam.txt")
>
> Suppose, instead, that Python had a syntax like this:
>
> def foo(fixed_arg, spam=>{}, ham=>[], jam=>open("jam.txt")):
>     """Foo the fixed_arg against the spam mapping, the
>     ham sequence, and the jam file."""
>
> The expressions would be evaluated as closures, using the same scope
> that the function's own definition used. (This won't keep things alive
> unnecessarily, as the function's body will be nested within that same
> scope anyway.) Bikeshed the syntax all you like, but this would be
> something to point people to: "here's how to get late-binding
> semantics". For the purposes of documentation, the exact text of the
> parameter definition could be retained, and like docstrings, they
> could be discarded in -OO mode.
>
> Would this satisfy the people who get confused about "=[]"?
>
> ChrisA

Rather than a dedicated syntax, might this be something that could be
handled by a built-in decorator?

Maybe something like:

@late_binding
def myfunc(x, y=[]):

@late_binding('z')
def myfunc(x, y=expensive(), z=[]):

M = 5
@late_binding('z', vars_early=True)
def myfunc(x, y=expensive(), z=list(range(n))):

The big advantage, as shown in the last example, is that it could be
possible to specify early our late binding for variables as well.


From rosuav at gmail.com  Sat Nov 21 03:46:17 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 21 Nov 2015 19:46:17 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAFpSVpJ1MOaH=V9wxzgzkRzrSG0YoKQk7WQ4Fo1K5fd0QLPBuQ@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <CAFpSVpJ1MOaH=V9wxzgzkRzrSG0YoKQk7WQ4Fo1K5fd0QLPBuQ@mail.gmail.com>
Message-ID: <CAPTjJmpP2j4v4DiY_wdp70rcTCFkjkXpkp9J4UhDZ388Lxvq+w@mail.gmail.com>

On Sat, Nov 21, 2015 at 7:38 PM, Todd <toddrjen at gmail.com> wrote:
> Rather than a dedicated syntax, might this be something that could be
> handled by a built-in decorator?
>
> Maybe something like:
>
> @late_binding
> def myfunc(x, y=[]):

No, it can't; by the time the decorator runs, the expression has
already been evaluated. Without syntax, this can only be done with
gross hacks like lambda functions.

It could be done thus:

@late_binding
def myfunc(x, y=lambda: []):

and then the decorator could wrap the function. I'm not entirely sure
I could implement it reliably, but even leaving that aside, having to
put "lambda:" in front of everything is pretty ugly.

ChrisA


From vostrushka at gmail.com  Sat Nov 21 05:41:57 2015
From: vostrushka at gmail.com (vostrushka at gmail.com)
Date: Sat, 21 Nov 2015 02:41:57 -0800 (PST)
Subject: Problem to read from array
Message-ID: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>

Hi,
I have a file with one parameter per line:
a1
b1
c1
a2
b2
c2
a3
b3
c3
...
The parameters are lines of characters (not numbers)

I need to load it to 2D array for further manipulations.
So far I managed to upload this file into 1D array:

ParametersRaw = []
with open(file1) as fh:
    ParametersRaw = fh.readlines()
fh.close()

NumberOfColumns = 7
NumberOfRows = len(ParametersRaw)/NumberOfColumns

Parameters = [[],[]]
i=0
j=0
k=0
while (i < NumberOfRows):
    while (j < NumberOfColumns):
        k = (i*NumberOfColumns)+j
        Parameters[i][j] = ParametersRaw[k]
        j = j + 1
    i = i + 1
    j = 0

it fails at the line "Parameters[i][j] = ParametersRaw[k]" with error:

IndexError: index 0 is out of bounds for axis 0 with size 0

In case of populating 1D array I would use append() method.
But in case of 2D I am lost of how append() can be applied.
Could some one help newbie.

CU


From __peter__ at web.de  Sat Nov 21 06:23:31 2015
From: __peter__ at web.de (Peter Otten)
Date: Sat, 21 Nov 2015 12:23:31 +0100
Subject: Problem to read from array
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
Message-ID: <n2pk7m$v3j$1@ger.gmane.org>

vostrushka at gmail.com wrote:

> Hi,
> I have a file with one parameter per line:
> a1
> b1
> c1
> a2
> b2
> c2
> a3
> b3
> c3
> ...
> The parameters are lines of characters (not numbers)
> 
> I need to load it to 2D array for further manipulations.
> So far I managed to upload this file into 1D array:
> 
> ParametersRaw = []

No need for this assignment as you throw the value away.
> with open(file1) as fh:
>     ParametersRaw = fh.readlines()
> fh.close()

The with open() ... statement already ensures that the file is closed.

> NumberOfColumns = 7
> NumberOfRows = len(ParametersRaw)/NumberOfColumns
> 
> Parameters = [[],[]]
> i=0
> j=0
> k=0
> while (i < NumberOfRows):
>     while (j < NumberOfColumns):
>         k = (i*NumberOfColumns)+j
>         Parameters[i][j] = ParametersRaw[k]

The inner lists Parameters[i] are empty so every assignment

Parameters[i][k] = ...

will fail. While the minimal fix is to use append()

          Parameters[i].append(ParametersRaw[k])

you will run into the same problem with the rows if there are more than the 
two you prepared for in the line

> Parameters = [[],[]]

>         j = j + 1
>     i = i + 1
>     j = 0
> 
> it fails at the line "Parameters[i][j] = ParametersRaw[k]" with error:
> 
> IndexError: index 0 is out of bounds for axis 0 with size 0
> 
> In case of populating 1D array I would use append() method.
> But in case of 2D I am lost of how append() can be applied.
> Could some one help newbie.

As a general remark in idiomatic Python the loop

i = 0
while i < THRESHOLD:
   ...
   i = i + 1

is written as a for loop with range():

for i in range(THRESHOLD):
   ...

For your specific problem list slicing is a good approach:

COLUMNS = 7
with open(file1) as f:
    parameters_raw = f.readlines()

parameters = []
for row_start in range(0, len(parameters_raw), COLUMNS):
    parameters.append(parameters_raw[row_start:row_start+COLUMNS])


 





From gengyangcai at gmail.com  Sat Nov 21 08:20:05 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 21 Nov 2015 05:20:05 -0800 (PST)
Subject: *= operator
Message-ID: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>

This is a piece of code that calculates tax and tip :

def tax(bill):
    """Adds 8% tax to a restaurant bill."""
    bill *= 1.08
    print "With tax: %f" % bill
    return bill

def tip(bill):
    """Adds 15% tip to a restaurant bill."""
    bill *= 1.15
    print "With tip: %f" % bill
    return bill
    
meal_cost = 100
meal_with_tax = tax(meal_cost)
meal_with_tip = tip(meal_with_tax)

Does bill *= 1.08 mean bill = bill * 1.15 ?


From bc at freeuk.com  Sat Nov 21 08:37:25 2015
From: bc at freeuk.com (BartC)
Date: Sat, 21 Nov 2015 13:37:25 +0000
Subject: *= operator
In-Reply-To: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
References: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
Message-ID: <n2prun$3du$1@dont-email.me>

On 21/11/2015 13:20, Cai Gengyang wrote:
> This is a piece of code that calculates tax and tip :
>
> def tax(bill):
>      """Adds 8% tax to a restaurant bill."""
>      bill *= 1.08
>      print "With tax: %f" % bill
>      return bill
>
> def tip(bill):
>      """Adds 15% tip to a restaurant bill."""
>      bill *= 1.15
>      print "With tip: %f" % bill
>      return bill
>
> meal_cost = 100
> meal_with_tax = tax(meal_cost)
> meal_with_tip = tip(meal_with_tax)
>
> Does bill *= 1.08 mean bill = bill * 1.15 ?

bill *= 1.08 would mean bill = bill*1.08 (not 1.15; I assume that's a typo).

Although you can never be 100% sure in Python (as * or *= could have 
been redefined to do something else), there's no reason to suspect that 
here.

Also, there's probably some technical difference that someone could up 
with (*= doing in-place modification for example), but that shouldn't 
matter when bill is just a number.

-- 
Bartc



From steve at pearwood.info  Sat Nov 21 08:39:44 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 22 Nov 2015 00:39:44 +1100
Subject: *= operator
References: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
Message-ID: <56507422$0$1594$c3e8da3$5496439d@news.astraweb.com>

On Sun, 22 Nov 2015 12:20 am, Cai Gengyang wrote:

> Does bill *= 1.08 mean bill = bill * 1.15 ?

No. It means `bill = bill * 1.08`, not 1.15.



-- 
Steven



From frank at chagford.com  Sat Nov 21 08:46:46 2015
From: frank at chagford.com (Frank Millman)
Date: Sat, 21 Nov 2015 15:46:46 +0200
Subject: *= operator
In-Reply-To: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
References: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
Message-ID: <n2pskb$m43$1@ger.gmane.org>

"Cai Gengyang"  wrote in message 
news:a76b1b5b-4321-41bb-aeca-0dac787752d9 at googlegroups.com...

> This is a piece of code that calculates tax and tip :
>
> def tax(bill):
>     """Adds 8% tax to a restaurant bill."""
>     bill *= 1.08
>     print "With tax: %f" % bill
>     return bill
>
> def tip(bill):
>     """Adds 15% tip to a restaurant bill."""
>     bill *= 1.15
>     print "With tip: %f" % bill
>     return bill
>
> meal_cost = 100
> meal_with_tax = tax(meal_cost)
> meal_with_tip = tip(meal_with_tax)
>
> Does bill *= 1.08 mean bill = bill * 1.15 ?

Firstly, I assume that you actually meant 'bill = bill * 1.08' at the end of 
the last line.

Secondly, how can I help you to answer this kind of question yourself.

Here are two ways.

1. Try it out at the interpreter -

c:\>
Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit 
(AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> bill = 100
>>> bill *= 1.08
>>> bill

I deliberately omitted the last line. Try it yourself and see what you get.

2. Read the fine manual.

The Index has a section headed 'Symbols'. From there you will find '*=', 
with a link to 'augmented assignment'.

If you follow the link, you will find a detailed explanation. Here is an 
excerpt -

"An augmented assignment expression like x += 1 can be rewritten as x = x + 
1 to achieve a similar, but not exactly equal effect. In the augmented 
version, x is only evaluated once. Also, when possible, the actual operation 
is performed in-place, meaning that rather than creating a new object and 
assigning that to the target, the old object is modified instead."

Frank Millman




From gengyangcai at gmail.com  Sat Nov 21 08:55:49 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 21 Nov 2015 05:55:49 -0800 (PST)
Subject: *= operator
In-Reply-To: <mailman.35.1448113630.2291.python-list@python.org>
References: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
 <mailman.35.1448113630.2291.python-list@python.org>
Message-ID: <43e70c39-30a0-45c6-9414-c98304bf829f@googlegroups.com>

>>> bill = 100
>>> bill *= 1.08
>>> bill
108.0
>>> 




On Saturday, November 21, 2015 at 9:47:29 PM UTC+8, Frank Millman wrote:
> "Cai Gengyang"  wrote in message 
> news:a76b1b5b-4321-41bb-aeca-0dac787752d9 at googlegroups.com...
> 
> > This is a piece of code that calculates tax and tip :
> >
> > def tax(bill):
> >     """Adds 8% tax to a restaurant bill."""
> >     bill *= 1.08
> >     print "With tax: %f" % bill
> >     return bill
> >
> > def tip(bill):
> >     """Adds 15% tip to a restaurant bill."""
> >     bill *= 1.15
> >     print "With tip: %f" % bill
> >     return bill
> >
> > meal_cost = 100
> > meal_with_tax = tax(meal_cost)
> > meal_with_tip = tip(meal_with_tax)
> >
> > Does bill *= 1.08 mean bill = bill * 1.15 ?
> 
> Firstly, I assume that you actually meant 'bill = bill * 1.08' at the end of 
> the last line.
> 
> Secondly, how can I help you to answer this kind of question yourself.
> 
> Here are two ways.
> 
> 1. Try it out at the interpreter -
> 
> c:\>
> Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit 
> (AMD64)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> bill = 100
> >>> bill *= 1.08
> >>> bill
> 
> I deliberately omitted the last line. Try it yourself and see what you get.
> 
> 2. Read the fine manual.
> 
> The Index has a section headed 'Symbols'. From there you will find '*=', 
> with a link to 'augmented assignment'.
> 
> If you follow the link, you will find a detailed explanation. Here is an 
> excerpt -
> 
> "An augmented assignment expression like x += 1 can be rewritten as x = x + 
> 1 to achieve a similar, but not exactly equal effect. In the augmented 
> version, x is only evaluated once. Also, when possible, the actual operation 
> is performed in-place, meaning that rather than creating a new object and 
> assigning that to the target, the old object is modified instead."
> 
> Frank Millman


From joel.goldstick at gmail.com  Sat Nov 21 08:58:34 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sat, 21 Nov 2015 08:58:34 -0500
Subject: *= operator
In-Reply-To: <56507422$0$1594$c3e8da3$5496439d@news.astraweb.com>
References: <a76b1b5b-4321-41bb-aeca-0dac787752d9@googlegroups.com>
 <56507422$0$1594$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPM-O+y93fZ-nS9vz1d_viJVGdDAz9ncFgKpt6_aS19E6kMKag@mail.gmail.com>

On Sat, Nov 21, 2015 at 8:39 AM, Steven D'Aprano <steve at pearwood.info>
wrote:

> On Sun, 22 Nov 2015 12:20 am, Cai Gengyang wrote:
>
> > Does bill *= 1.08 mean bill = bill * 1.15 ?
>
> No. It means `bill = bill * 1.08`, not 1.15.
>
>
>
> --
> Steven
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>

Others have answered, but don't forget to try things like this yourself in
the interactive python shell of your choice:

Python 2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> bill = 1
>>> bill *=1.08
>>> bill
1.08
>>>



-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From lac at openend.se  Sat Nov 21 09:22:55 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 21 Nov 2015 15:22:55 +0100
Subject: Problem to read from array
In-Reply-To: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
Message-ID: <201511211422.tALEMtE0032395@fido.openend.se>

In Python we don't write while loops that often.
instead we do:

for i in range(NumberOfColumns):
    for j in range(NumberOfRows):
    	do_something()

But for the particular case that you are after, constructing lists,
we have something even neater -- list comprehensions.

So you might write:

 >>> newarray=[]
 >>> for i in range(3):
 ...     newarray[i] = i

And this would not work.

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
IndexError: list assignment index out of range

At this point you might get a bit frustrated.  Python is happily telling
you that you don't have a newarray[0][0] which is hardly news to you who
was trying to initialise the thing.

The trick is to initialise it with a list comprehension.

You write one like this:
[ calculate_something() for i in range(LIMIT)]

This works:
 >>> newarray = [i for i in range(3)]
 >>> newarray 
[0, 1, 2]
 >>> 

As does
 >>> newarray = ["hello" for i in range(3)]
 >>> newarray
['hello', 'hello', 'hello']

You can even build your lists with a condition:
 >>> even_numbers=[x for x in range(11) if x % 2 == 0]
 >>> even_numbers
[0, 2, 4, 6, 8, 10]

You are not limited to one dimentional arrays (lists) here.  You
can have much more complicated expressions as the calculate_something.

 >>> newarray =[[ [x+2000, y*y] for x in range(3)] for y in range(5)]
 >>> newarray
[[[2000, 0], [2001, 0], [2002, 0]], [[2000, 1], [2001, 1], [2002, 1]], 
[[2000, 4], [2001, 4], [2002, 4]], [[2000, 9], [2001, 9], [2002, 9]], 
[[2000, 16], [2001, 16], [2002, 16]]]

Which leads us to a particularly useful construct:
 >>> emptyarray =[[ [] for x in range(3)] for y in range(5)]
 >>> emptyarray
[[[], [], []], [[], [], []], [[], [], []], [[], [], []], [[], [], []]]

Bingo.  Now you won't have any index errors when you try to append
to your x,y values.

Hope this is useful.
Also, there is the tutor mailing list
https://mail.python.org/mailman/listinfo/tutor
which you might be interested in, where we discuss things like this.
Peter Otten is there, too.

Laura



From ian.g.kelly at gmail.com  Sat Nov 21 10:01:05 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Sat, 21 Nov 2015 08:01:05 -0700
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmpP2j4v4DiY_wdp70rcTCFkjkXpkp9J4UhDZ388Lxvq+w@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <CAFpSVpJ1MOaH=V9wxzgzkRzrSG0YoKQk7WQ4Fo1K5fd0QLPBuQ@mail.gmail.com>
 <CAPTjJmpP2j4v4DiY_wdp70rcTCFkjkXpkp9J4UhDZ388Lxvq+w@mail.gmail.com>
Message-ID: <CALwzidkaASG257RsygKUF1FRnHtttK8Q3pkvPEW34YPn80QSpg@mail.gmail.com>

On Sat, Nov 21, 2015 at 1:46 AM, Chris Angelico <rosuav at gmail.com> wrote:
> On Sat, Nov 21, 2015 at 7:38 PM, Todd <toddrjen at gmail.com> wrote:
>> Rather than a dedicated syntax, might this be something that could be
>> handled by a built-in decorator?
>>
>> Maybe something like:
>>
>> @late_binding
>> def myfunc(x, y=[]):
>
> No, it can't; by the time the decorator runs, the expression has
> already been evaluated. Without syntax, this can only be done with
> gross hacks like lambda functions.
>
> It could be done thus:
>
> @late_binding
> def myfunc(x, y=lambda: []):
>
> and then the decorator could wrap the function. I'm not entirely sure
> I could implement it reliably, but even leaving that aside, having to
> put "lambda:" in front of everything is pretty ugly.

Note that "lambda: []" can also be spelled "list".


From lac at openend.se  Sat Nov 21 10:05:20 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 21 Nov 2015 16:05:20 +0100
Subject: Problem to read from array
In-Reply-To: <201511211422.tALEMtE0032395@fido.openend.se>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <201511211422.tALEMtE0032395@fido.openend.se>
Message-ID: <201511211505.tALF5K8r003004@fido.openend.se>

In a message of Sat, 21 Nov 2015 15:22:55 +0100, Laura Creighton writes:
>At this point you might get a bit frustrated.  Python is happily telling
>you that you don't have a newarray[0][0] which is hardly news to you who
>was trying to initialise the thing.

My bad.  I was thinking about 2 dimentional arrays, but of course that
error is just that newarray[0] doesn't exit.

(So why is it that I can read an article 3 times, find no more errors,
post it, and _then_ discover one?!)

Laura


From bc at freeuk.com  Sat Nov 21 10:26:34 2015
From: bc at freeuk.com (BartC)
Date: Sat, 21 Nov 2015 15:26:34 +0000
Subject: Problem to read from array
In-Reply-To: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
Message-ID: <n2q2bd$rf0$1@dont-email.me>

On 21/11/2015 10:41, vostrushka at gmail.com wrote:
> Hi,
> I have a file with one parameter per line:
> a1
> b1
> c1
> a2
> b2
> c2
> a3
> b3
> c3
> ...
> The parameters are lines of characters (not numbers)
>
> I need to load it to 2D array for further manipulations.
> So far I managed to upload this file into 1D array:
>
> ParametersRaw = []
> with open(file1) as fh:
>      ParametersRaw = fh.readlines()
> fh.close()

I tried this code based on yours:

with open("input") as fh:
     lines=fh.readlines()

rows = len(lines)//3

params=[]
index=0

for row in range(rows):
     params.append([lines[index],lines[index+1],lines[index+2]])
     index += 3

for row in range(rows):
     print (row,":",params[row])

For the exact input you gave, it produced this output:

0 : ['a1\n', 'b1\n', 'c1\n']
1 : ['a2\n', 'b2\n', 'c2\n']
2 : ['a3\n', 'b3\n', 'c3\n']

Probably you'd want to get rid of those \n characters. (I don't know how 
off-hand as I'm not often write in Python.)

The last bit could also be written:

for param in params:
     print (params)

but I needed the row index.

-- 
BartC


From nhilterbrand at gmail.com  Sat Nov 21 10:52:06 2015
From: nhilterbrand at gmail.com (Nathan Hilterbrand)
Date: Sat, 21 Nov 2015 10:52:06 -0500
Subject: Problem to read from array
In-Reply-To: <n2q2bd$rf0$1@dont-email.me>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <n2q2bd$rf0$1@dont-email.me>
Message-ID: <56509326.70906@gmail.com>


On 11/21/2015 10:26 AM, BartC wrote:
> On 21/11/2015 10:41, vostrushka at gmail.com wrote:
>> Hi,
>> I have a file with one parameter per line:
>> a1
>> b1
>> c1
>> a2
>> b2
>> c2
>> a3
>> b3
>> c3
>> ...
>> The parameters are lines of characters (not numbers)
>>
>> I need to load it to 2D array for further manipulations.
>> So far I managed to upload this file into 1D array:
>>
>> ParametersRaw = []
>> with open(file1) as fh:
>>      ParametersRaw = fh.readlines()
>> fh.close()
>
> I tried this code based on yours:
>
> with open("input") as fh:
>     lines=fh.readlines()
>
> rows = len(lines)//3
>
> params=[]
> index=0
>
> for row in range(rows):
>     params.append([lines[index],lines[index+1],lines[index+2]])
>     index += 3
>
> for row in range(rows):
>     print (row,":",params[row])
>
> For the exact input you gave, it produced this output:
>
> 0 : ['a1\n', 'b1\n', 'c1\n']
> 1 : ['a2\n', 'b2\n', 'c2\n']
> 2 : ['a3\n', 'b3\n', 'c3\n']
>
> Probably you'd want to get rid of those \n characters. (I don't know 
> how off-hand as I'm not often write in Python.)
>
> The last bit could also be written:
>
> for param in params:
>     print (params)
>
> but I needed the row index.
>
To get rid of the '\n' (lineend) characters:

with open(file1) as fh:
     ParametersRaw = [line.strip() for line in fh.readlines()]

or, more succinctly..

  with open(file1) as fh:
      ParametersRaw = [line.strip() for line in fh]

Comprehensions are your friend.

Nathan


From sailor at lists.xtsubasa.org  Sat Nov 21 11:57:37 2015
From: sailor at lists.xtsubasa.org (Pavel Volkov)
Date: Sat, 21 Nov 2015 19:57:37 +0300
Subject: anyone tell me why my program will not =?iso-8859-1?Q?run=3F?=
In-Reply-To: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <f56617d4-11e9-48d1-b7fe-3eb0dca89e0e@lists.xtsubasa.org>

On ???????, 21 ?????? 2015 ?. 6:30:02 MSK, Dylan Riley wrote:
> i am learning python and was tasked with making a program that 
> flips a coin 100 times and then tells you
> the number of heads and tails.
>

First, you have a syntax error:
if result = heads:
should be:
if result == heads:

Second, there's incorrent indentation, your while loop is almost empty (not 
syntax error though).


From rosuav at gmail.com  Sat Nov 21 12:02:13 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 22 Nov 2015 04:02:13 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CALwzidkaASG257RsygKUF1FRnHtttK8Q3pkvPEW34YPn80QSpg@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <CAFpSVpJ1MOaH=V9wxzgzkRzrSG0YoKQk7WQ4Fo1K5fd0QLPBuQ@mail.gmail.com>
 <CAPTjJmpP2j4v4DiY_wdp70rcTCFkjkXpkp9J4UhDZ388Lxvq+w@mail.gmail.com>
 <CALwzidkaASG257RsygKUF1FRnHtttK8Q3pkvPEW34YPn80QSpg@mail.gmail.com>
Message-ID: <CAPTjJmpMkUTxfLT7gztGTB1Hq4uvkX4E0MpJzpDy2_z=5W39cg@mail.gmail.com>

On Sun, Nov 22, 2015 at 2:01 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> and then the decorator could wrap the function. I'm not entirely sure
>> I could implement it reliably, but even leaving that aside, having to
>> put "lambda:" in front of everything is pretty ugly.
>
> Note that "lambda: []" can also be spelled "list".

In that particular example, yes. I kept it in the large form to
maintain the parallel with the version I was quoting. But if the
decorator were to be written, it would probably be something along the
lines of "if the default is callable, do the late-binding magic", so
'list' would work just fine.

ChrisA


From sailor at lists.xtsubasa.org  Sat Nov 21 12:15:05 2015
From: sailor at lists.xtsubasa.org (Pavel Volkov)
Date: Sat, 21 Nov 2015 20:15:05 +0300
Subject: anyone tell me why my program will not =?iso-8859-1?Q?run=3F?=
In-Reply-To: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <43bd9327-3fc8-4264-a62e-f4a62f21e21c@lists.xtsubasa.org>

On ???????, 21 ?????? 2015 ?. 6:30:02 MSK, Dylan Riley wrote:

Also some more notes:

> heads = int("1")
> tails = int("2")

Why use this strange initialization? The usual way:
heads = 1
tails = 2
gives the same result.

> while flips != 0:
>     flips -= 1

There's no need to use while and flips variable:

for _ in range(100):
    if random.randint(heads, tails) == heads:
        headscount += 1
    else:
        tailscount += 1
  
Also, it's good to put import at the beginning.


From david007killer at gmail.com  Sat Nov 21 13:49:21 2015
From: david007killer at gmail.com (david burstein)
Date: Sat, 21 Nov 2015 10:49:21 -0800 (PST)
Subject: using re.split function
Message-ID: <f810df9d-5691-467c-b212-7799dfdbb38d@googlegroups.com>

im pretty new in python and i didnt get how to use the re.split function.
for example if i have a string and i want to split it by two conditions:
first one splitting when " [ " appears second one when "]" appears


From python at mrabarnett.plus.com  Sat Nov 21 14:20:55 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Sat, 21 Nov 2015 19:20:55 +0000
Subject: using re.split function
In-Reply-To: <f810df9d-5691-467c-b212-7799dfdbb38d@googlegroups.com>
References: <f810df9d-5691-467c-b212-7799dfdbb38d@googlegroups.com>
Message-ID: <5650C417.9060400@mrabarnett.plus.com>

On 2015-11-21 18:49, david burstein wrote:
> im pretty new in python and i didnt get how to use the re.split function.
> for example if i have a string and i want to split it by two conditions:
> first one splitting when " [ " appears second one when "]" appears
>
re.split(r" \[ |\]", string)

You need to escape the "[" because it normally indicates the start of a
character set.



From teamprimalforce at gmail.com  Sat Nov 21 16:27:52 2015
From: teamprimalforce at gmail.com (Lee Bradley)
Date: Sat, 21 Nov 2015 13:27:52 -0800 (PST)
Subject: need help understanding a python program
In-Reply-To: <mailman.71.1446489928.4463.python-list@python.org>
References: <f25cc66a-3003-41cb-8c47-bbece515c275@googlegroups.com>
 <mailman.71.1446489928.4463.python-list@python.org>
Message-ID: <0408f311-270d-49cb-9a21-48310bfa82f8@googlegroups.com>

On Monday, November 2, 2015 at 1:45:58 PM UTC-5, Ben Finney wrote:
> Lee Bradley <bradley_lee_r at sbcglobal.net> writes:
> 
> > http://pastebin.com/ndDYjYe1
> 
> We much prefer to discuss code in the context of plain text messages
> right here, because this forum is archived longer than the expected
> lifetime of content hosted on other services.
> 
> > For now I am looking for someone who can dig into this code and
> > explain what's going on. I understand a lot of it but not enough to
> > really *get it*.
> 
> Could you discuss your own impressions of it so far, with (parts of) the
> code pasted here as plain text for context of your commentary?
> 
> -- 
>  \       Moriarty: "Forty thousand million billion dollars? That money |
>   `\            must be worth a fortune!" --The Goon Show, _The Sale of |
> _o__)                                                       Manhattan_ |
> Ben Finney

Ben,

Sorry it took so long to get back on this. I did start to put together a response to you. I made all sorts of notes about what I understood and what I didn't understand. But in the end I tried to write a solution myself using his ideas and what I had learned from many things I learned on the subject.

I believe I have a working program which I have written in C.

http://primepuzzle.com/tc/entropy.c

Incredibly interesting exercise. I am awaiting any feedback Vitaly might have on what I have built.

Lee


From gengyangcai at gmail.com  Sat Nov 21 17:16:27 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 21 Nov 2015 14:16:27 -0800 (PST)
Subject: Comparators
Message-ID: <da205c85-b569-47a6-9708-8cd7d6c5205e@googlegroups.com>

Comparators, interesting ...

>>> booltwo = (10 + 18) == 3**17
>>> booltwo
False
>>> boolone = (50 - 35) > 35
>>> boolone
False
>>> booltwo = (65 - 35) > 15
>>> booltwo
True
>>> boolalpha = 3 < 6
>>> boolalpha
True
>>> boolbeta = 100 == 10*30
>>> boolbeta
False
>>> 


From jon+usenet at unequivocal.co.uk  Sat Nov 21 17:21:53 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Sat, 21 Nov 2015 22:21:53 -0000 (UTC)
Subject: Comparators
References: <da205c85-b569-47a6-9708-8cd7d6c5205e@googlegroups.com>
Message-ID: <slrnn51roe.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-21, Cai Gengyang <gengyangcai at gmail.com> wrote:
> Comparators, interesting ...
>
>>>> booltwo = (10 + 18) == 3**17
>>>> booltwo
> False

What's interesting about that?


From gengyangcai at gmail.com  Sat Nov 21 17:49:36 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 21 Nov 2015 14:49:36 -0800 (PST)
Subject: Comparators
In-Reply-To: <slrnn51roe.1t1.jon+usenet@frosty.unequivocal.co.uk>
References: <da205c85-b569-47a6-9708-8cd7d6c5205e@googlegroups.com>
 <slrnn51roe.1t1.jon+usenet@frosty.unequivocal.co.uk>
Message-ID: <e686b079-0e22-4ee9-a8a0-b46b159bf7f7@googlegroups.com>

Hmm .. I am a slow learner and have poor memory. Sometimes when I see a new programming operator, I have to type it out so that I can remember it and let it sink into my brain 

On Sunday, November 22, 2015 at 6:24:28 AM UTC+8, Jon Ribbens wrote:
> On 2015-11-21, Cai Gengyang <gengyangcai at gmail.com> wrote:
> > Comparators, interesting ...
> >
> >>>> booltwo = (10 + 18) == 3**17
> >>>> booltwo
> > False
> 
> What's interesting about that?



From rosuav at gmail.com  Sat Nov 21 18:00:51 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 22 Nov 2015 10:00:51 +1100
Subject: Comparators
In-Reply-To: <e686b079-0e22-4ee9-a8a0-b46b159bf7f7@googlegroups.com>
References: <da205c85-b569-47a6-9708-8cd7d6c5205e@googlegroups.com>
 <slrnn51roe.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <e686b079-0e22-4ee9-a8a0-b46b159bf7f7@googlegroups.com>
Message-ID: <CAPTjJmqKHjjKiiY06C5ajeqeZSchTAtWDqEM2z1SBswm5foAkQ@mail.gmail.com>

On Sun, Nov 22, 2015 at 9:49 AM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> Hmm .. I am a slow learner and have poor memory. Sometimes when I see a new programming operator, I have to type it out so that I can remember it and let it sink into my brain
>

I recommend creating a text file of notes. Every time you learn
something new, add it to your notes file - and commit the change to
git. Then, when you come back to the file, you'll have one of several
reactions:

1) "Yeah, that's right! Good stuff to remember." - it's done its job
by reminding you.
2) "Wait, what? How does that work?" - add some clarification notes.
3) "Of course it's like that. I know that. Don't need that any more."
- remove it (and commit the change to git).

Every time #3 comes up, you know you're learning - you're becoming a
better programmer. And it will, often. This isn't something just for
"novice" or "beginning" programmers, either; I have a file like that,
although not only about programming. (This week, I added notes about
using iptables to NAT from one IP address to a completely different
one, and change the port number used, which basically let me deploy a
temporary bouncer on a cheap cloud server, getting around a temporary
outage here. Worth doing.) Some stuff will stay there for a long time,
ready for you to look it up whenever you need it. Other stuff will
come and go. All of it is useful.

ChrisA


From orgnut at yahoo.com  Sat Nov 21 21:44:17 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Sat, 21 Nov 2015 18:44:17 -0800
Subject: anyone tell me why my program will not run?
In-Reply-To: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <dr2dnegom5afsczLnZ2dnUU7-bmdnZ2d@giganews.com>

On 11/20/2015 07:30 PM, Dylan Riley wrote:
> i am learning python and was tasked with making a program that flips a coin 100 times and then tells you
> the number of heads and tails.
>
> I have done so coming up with this piece of work but it doesnt run can anyone help me out?
>
> #This is credited to dylan
>
> print(" \\ \\ \\ \\ \\ \\ \\ \\ D FLIPS \\ \\ \\ \\ \\ \\ \\ \\")
> print("\n\nThis is D's coin flipper program. You get 100 flips. \n\t LETS SEE HOW LUCKY YOU ARE")
> input("Press enter")
>
> import random
>
> heads = int("1")
> tails = int("2")
> flips = 100
> headscount = 0
> tailscount = 0
>
> while flips != 0:
>      flips -= 1
>
> result = random.randint(heads, tails)
> if result = heads:
>      headscount += 1
> else:
>      tailscount += 1
>
>
> print(headscount, tailscount)
>
> input("press enter to exit")
>
It doesn't run because it if full of errors, which have already been discussed by others.

I just wanted to show you a (radically) different approach that you can study (or not... your 
choice).  I'm leaving out your heading and just showing the heart of the program.  I am not 
necessarily recommending this, I just wanted you to see a different way of looking at the 
problem.  Except for the initialization and printing of the results, the entire thing is done in 
one two-line for loop.

<code>
from random import randint

#  Put your heading text here...

HEADS = 0
TAILS = 1    #  Note:  Python _convention_ is to upper-case constants.
counts = [0, 0]

for flips in range(100):
     counts[randint(0, 1)] += 1

print('Number of heads: ', counts[HEADS])
print('Number of tails: ', counts[TAILS])
</code>

Note that the HEADS and TAILS constants are only used in one place (the final print functions), 
you could simply leave them out and directly use 0 and 1 in those final print()s.

      -=- Larry -=-



From benjamin at python.org  Sat Nov 21 21:48:27 2015
From: benjamin at python.org (Benjamin Peterson)
Date: Sat, 21 Nov 2015 18:48:27 -0800
Subject: [RELASE] Python 2.7.11 release candidate 1
Message-ID: <1448160507.1985354.446437097.5E584CD6@webmail.messagingengine.com>

Greetings,
It is my duty and honor to announce the immediate availability of Python
2.7.11 release candidate 1. Python 2.7.11 will be another bug fix
release for the 2.7.x series.

Downloads are at:

    https://www.python.org/downloads/release/python-2711rc1/

Please test the candidate and report bugs to

   https://bugs.python.org

If no serious problems are found, 2.7.11 final will be released in two
weeks.

Regards,
Benjamin Peterson
(on behalf of Python 2.7.11's contributors)


From steve at pearwood.info  Sat Nov 21 22:43:42 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 22 Nov 2015 14:43:42 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
Message-ID: <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 10:59 pm, BartC wrote:

> On 20/11/2015 01:05, Steven D'Aprano wrote:

>> Here's another use for function defaults, as static storage:
[...]
>> This is a quick and easy way to memoise a function which would otherwise
>> be horribly slow. And it only works because _memo is bound to a mutable
>> object once, and once only.
> 
> We're arguing at cross-purposes then since you are obviously interested
> in these esoteric aspects, 

Memoisation isn't "esoteric", it is a simple, basic and widely-used
technique used to improve performance of otherwise expensive functions.
Quite frankly, to call it such demonstrates a considerable level of
ignorance about basic programming idioms. Not just Python, but general
purpose programming.

Instead of being so judgemental, why don't you take this as an opportunity
to open your mind to new programming styles? The purpose of learning a new
language is to open our minds to new ways of solving problems. If all we
are going to do is bitch and moan that the new language isn't exactly the
same as the old one we already know, we might as well just stick to using
the old one and not even bother learning anything new.


> but all I want to do is avoid remembering a 
> long list of defaults. Here's an example from another language, a 
> function I'm working on at the minute:
[...]
> (Here, however, the language doesn't like you doing in-place
> modification of a parameter unless the '&' is used, in which case you
> wouldn't be able to assign a default value such as () as you can only
> pass l-values.)

It sounds to me like you have implemented something like Pascal's "var"
parameters, is that right? I believe some languages (VB perhaps?) call
them "output parameters".


>> def test(arg=[]):
>>      arg.append(1)
>>      return len(arg)
>>
>>
>> The binding arg=[] is NOT inside the body of the function. Therefore, it
>> is NOT executed repeatedly, but only once.
> 
> OK, so the "=" is misleading if not a lie.

No. Why would you conclude that? If I called the function like so:

    test( [1, 2, 3, 4, 5] )

and got the result 6, would I conclude that the "=" is misleading if not a
lie? After all, the function declaration clearly shows arg being assigned
the value [], so why am I getting 6 as the result instead of 1?

The whole point of parameter default arguments is that they are bound to the
parameter *only* if the parameter otherwise isn't given a value. That's a
separate issue from *when* the default expression is evaluated. It can be
evaluated only once, or it can be evaluated every single time you call the
function. Both are legitimate techniques, both have their uses, and both
have their limitations.


>>>>> That [] doesn't look like an object that could change.
>>>>
>>>> Of course it does.
>>>
>>> You've lost me know.
> 
>> a = []
>> a.append(1)
>>
>> Are you shocked to learn that a is no longer an empty list?
> 
> No. But I would be surprised if, after this point, [] is no longer an
> empty list either!

Of course [] is an empty list. But the question isn't what [] represents, it
is what value `a` has. Since [] creates a list (not a tuple), and lists can
be modified in place, anyone familiar with Python should expect that just
because you see `a = []` somewhere doesn't mean that `a` will always be an
empty list. `a` can change.

(Of course, any variable can change if you re-assign it.)


> No, forget that; by now, I wouldn't be surprised at all!
> 
> (That [] isn't changed is probably thanks to [] being implemented with
> the BUILD_LIST byte-code, which constructs a brand-new empty list each
> time. So the next time [] is used, it will be a different one from the
> one that has just been appended to.

Right. That's not an accident either.

There isn't a single global empty list shared between all Python variables.
There *could be* (but probably isn't) a single global empty tuple, since
tuples are immutable and anything set to the empty tuple must remain the
empty tuple forever (or until re-assigned to something else), so there
would be no harm in having all such variables share the same object. But
lists don't work like that, because they are mutable.


> In my language, a construct such as [10,20,30] is evaluated just once at
> start-up.

I don't understand that explanation. How does that work? Given:

x = [10, 20, 30]
y = [10, 20, 30]


how does your language know what value y has if it doesn't evaluate the
second construct?



-- 
Steven



From steve at pearwood.info  Sat Nov 21 22:58:14 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 22 Nov 2015 14:58:14 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
 <n2kcdn$lq0$1@dont-email.me>
 <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <mailman.465.1447947763.16136.python-list@python.org>
Message-ID: <56513d58$0$1619$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 02:42 am, Ian Kelly wrote:

> On Thu, Nov 19, 2015 at 5:45 AM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> But if you want the default value to be evaluated exactly once, and once
>> only, there is no real alternative to early binding. You could use a
>> global variable, of course, but that is no solution -- that's a problem
>> waiting to happen.
> 
> It doesn't have to be a global. In a Python with late binding
> defaults, this would work to get early binding:
> 
> def f(x=f.default_x):
>     ...
> 
> f.default_x = something()


Ah, of course it can. Good catch.

As an illustration of how your expectations can colour your thinking, I
actually considered that, but rejected it as a possibility because
f.default_x couldn't be created until the function came into existence, and
the function couldn't come into existence until after f.default_x was
evaluated.

In other words, I was making the complementary error to BartC's: I was still
thinking in terms of early binding, when describing late binding.

In fact, what Python actually does is rather similar, except that instead
of "f.default_x" it uses f.__defaults__[0]. Roughly speaking, the function
declaration

def f(x=something()): ...

using early-binding is somewhat analogous to this using late-binding:

def f(x=f.__defaults__[0]): ...

f.__defaults__ = (something(), )


> Of course, assignment to function attributes is a relatively modern
> thing that is only permitted since Python 2.1, whereas function
> defaults have been around since at least 1.4, so this wouldn't have
> been an option when the semantics were being determined.

I suspect that had Guido decided on late binding as the preferred semantics,
he would have allowed function attributes much earlier.



-- 
Steven



From gengyangcai at gmail.com  Sun Nov 22 01:30:13 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 21 Nov 2015 22:30:13 -0800 (PST)
Subject: print("%.2f" % total)
Message-ID: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>


meal = 44.50
tax = 0.0675
tip = 0.15

meal = meal + meal * tax
total = meal + meal * tip

print("%.2f" % total)   

What do the lines inside the parentheses in this statement print("%.2f" % total) mean ? 

What does "%.2f" % total represent ?

Thanks alot ...

Gengyang


From stephane at wirtel.be  Sun Nov 22 02:01:02 2015
From: stephane at wirtel.be (Stephane Wirtel)
Date: Sun, 22 Nov 2015 08:01:02 +0100
Subject: print("%.2f" % total)
In-Reply-To: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
References: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
Message-ID: <20151122070102.GA1935@sg1>

print the two digits after the point.

On 11/21, Cai Gengyang wrote:
> 
> meal = 44.50
> tax = 0.0675
> tip = 0.15
> 
> meal = meal + meal * tax
> total = meal + meal * tip
> 
> print("%.2f" % total)   
> 
> What do the lines inside the parentheses in this statement print("%.2f" % total) mean ? 
> 
> What does "%.2f" % total represent ?
> 
> Thanks alot ...
> 
> Gengyang
> -- 
> https://mail.python.org/mailman/listinfo/python-list

-- 
St?phane Wirtel - http://wirtel.be - @matrixise


From rosuav at gmail.com  Sun Nov 22 02:21:46 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 22 Nov 2015 18:21:46 +1100
Subject: print("%.2f" % total)
In-Reply-To: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
References: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
Message-ID: <CAPTjJmrCVQRmUFR+B=CX8baxBGhByGkoqkwmCq9no9b6i3q4pQ@mail.gmail.com>

On Sun, Nov 22, 2015 at 5:30 PM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> What do the lines inside the parentheses in this statement print("%.2f" % total) mean ?
>
> What does "%.2f" % total represent ?
>

This is called "percent formatting" or "printf-style formatting". It's
a means of formatting a tuple of values (or in this case, a single
value) into a string; the percent sign introduces a format string, and
the letter (in this case 'f') ends it, and says what kind of
formatting to use. Everything else is just part of the string.

>>> "Hello, %s!" % "world"
'Hello, world!'
>>> "%d + %d = %o... in octal! I'M FINE!" % (4, 4, 8)
"4 + 4 = 10... in octal! I'M FINE!"

As you can see, you can play with this at the interactive prompt to
find out what's happening.

ChrisA


From frank at chagford.com  Sun Nov 22 02:29:54 2015
From: frank at chagford.com (Frank Millman)
Date: Sun, 22 Nov 2015 09:29:54 +0200
Subject: print("%.2f" % total)
In-Reply-To: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
References: <d34dc21b-fe74-40fc-9b54-c371105290f2@googlegroups.com>
Message-ID: <n2rqti$h27$1@ger.gmane.org>

"Cai Gengyang"  wrote in message 
news:d34dc21b-fe74-40fc-9b54-c371105290f2 at googlegroups.com...


> meal = 44.50
> tax = 0.0675
> tip = 0.15
>
> meal = meal + meal * tax
> total = meal + meal * tip
>
> print("%.2f" % total)
>
> What do the lines inside the parentheses in this statement print("%.2f" % 
> total) mean ?
>
> What does "%.2f" % total represent ?

>From the Fine Manual -

Index > Symbols > '%' > Formatting takes you to a section headed 
"printf-style String Formatting".

"Given format % values (where format is a string), % conversion 
specifications in format are replaced with zero or more elements of values"

A conversion specifier consists of two or more characters, of which the 
first is always '%', and the rest provide a wide variety of formatting 
options.

Precision (optional) is given as a '.' (dot) followed by the precision, so 
'.2' means show the result with a precision of 2.

'f' is a conversion type which represents 'floating point decimal format'.

Note the following warning -

"The formatting operations described here exhibit a variety of quirks that 
lead to a number of common errors (such as failing to display tuples and 
dictionaries correctly). Using the newer str.format() interface helps avoid 
these errors, and also provides a generally more powerful, flexible and 
extensible approach to formatting text."

Using str.format(), your example would look like this -

print('{:.2f}'.format(total))

Another word of warning. Using a format specifier displays the value nicely 
rounded to a number of decimal places, but the original value is unchanged. 
Use the interpreter to see what the actual value is. For serious work 
involving monetary values, you should look at the Decimal module.

Frank Millman




From steve at pearwood.info  Sun Nov 22 05:06:24 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 22 Nov 2015 21:06:24 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <n2n4ve$1no$1@dont-email.me>
Message-ID: <565193a1$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 11:53 pm, BartC wrote:

> On 20/11/2015 12:28, Marko Rauhamaa wrote:
>> Even more appropriately, you may expressly want a mutable, singleton
>> object to be the default:
>>
>>     def initiate_query(query, database=global_database):
> 
> Finally, a down-to-earth example. 

Really? Astonishing. To me, the Ackermann's function is a straight-forward,
simple example. It is, after all, a pure mathematical function in the true
sense: it has no side-effects, it takes some arguments, and returns a
result. (Of course, the Python implementation I gave has the side-effect of
keeping a cache of past results, but that's just an implementation detail.)

Whereas this initiate_query example is the opposite of straight-forward. It
involves a database, which means side-effects. The very opposite of a pure
function. Besides, I've never written database code in my life, which makes
it weird and exotic to me. (If lambda is exotic to you because your
personal experience happens to have avoided that area, databases are
equally exotic to me for the same reason.

The lesson here is: programming covers a HUGE range of topics. Don't assume
that the blind-spots in your experience don't exist or aren't important,
because they will be to someone. What's exotic to you is boring and
common-place to somebody else, and vice versa.



> Here it probably doesn't matter at 
> what point 'global_database' gets bound. You know it will always refer
> to the current state of global_database, 

No. You've got that completely backwards.

With early binding semantics (or "early evaluation" if you prefer), the
default object will be the value of global_data at the time the function
declaration runs. Subsequent rebindings of the global variable will not
effect the default object one iota, and you will always know that the
default for database will always be the same thing, whatever it was when
you first defined the function:


global_database = DB("abc")
def initiate_query(query, database=global_database):
    ...

global_database = DB("xyz")

initiate_query(query)  # here, the database used is "abc", not "xyz"


But with late binding, or "late evaluation", the opposite is the case: when
you finally call initiate_query, the database used will be "xyz". *This*
time. Next time, it could be something else: or even nothing at all, if the
global variable has been deleted.




-- 
Steven



From steve at pearwood.info  Sun Nov 22 07:01:59 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 22 Nov 2015 23:01:59 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
Message-ID: <5651aeb9$0$1601$c3e8da3$5496439d@news.astraweb.com>

On Fri, 20 Nov 2015 11:39 pm, BartC wrote:

> What's bothering me is:
> 
> * The large amount of mumbo-jumbo used to describe what's going on

Just because you don't know the terminology doesn't make it mumbo-jumbo. 

That's a particularly unfair and unjustified response to make when multiple
people have spent a lot of their own time, gratis, to explain what is going
on. If you are willing, you can learn a lot here, one of the few places
left where education is still free.


> * The insistence (I think largely from Steven) that the way this feature
> works is good rather than bad

It is good. It's just not good for *everything*.


> * The refusal to acknowledge that the def fn(a=[]) syntax is misleading.
> (What value will a have when you call fn()? The true answer is that you
> can't tell.)

I'm not really sure that anyone has disputed that specific point.

I'd say that the value of the default `a` could change, which is no
different from most other uses of mutable values. This is why some people
insist that mutable values are a mistake, and programming should only
involve immutable, fixed, values.


> * The persistent nonsense that somehow [] is mutable (what happens is
> that [] is assigned to a variable, and /that/ is mutable)

No, objects are mutable, or immutable, as the case may be



-- 
Steven



From marko at pacujo.net  Sun Nov 22 07:35:27 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sun, 22 Nov 2015 14:35:27 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me> <877flcrh26.fsf@elektro.pacujo.net>
 <n2n4ve$1no$1@dont-email.me>
 <565193a1$0$1593$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87poz29pps.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> Really? Astonishing. To me, the Ackermann's function is a
> straight-forward, simple example.

I must admit I have not once in my life written an implementation of the
Ackermann function.

> Whereas this initiate_query example is the opposite of
> straight-forward. It involves a database, which means side-effects.

Again, I must hang my head and confess that I have written quite many
functions with side effects.

> (If lambda is exotic to you because your personal experience happens
> to have avoided that area, databases are equally exotic to me for the
> same reason.

Lambdas are less exotic than layman programmers might think. You may
never need a lambda in Python but you will need to master closures and
inner classes.


Marko


From gandalf at shopzeus.com  Sun Nov 22 07:58:09 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Sun, 22 Nov 2015 13:58:09 +0100
Subject: ANN: yubistorm
Message-ID: <5651BBE1.8050208@shopzeus.com>

YubiStorm provides a simple module that can be used from a Tornado server to authenticate users with YubiCloud authentication servers.

The PyPi package contains the module for the API only. The repository contains an example web server that can be used to understand how YubiCloud authentication works in an async way.

PyPi: https://pypi.python.org/pypi/yubistorm
Documentation: http://pythonhosted.org/yubistorm/
Repository: https://bitbucket.org/nagylzs/yubistorm

Cheers,

   Laszlo



From bc at freeuk.com  Sun Nov 22 08:21:02 2015
From: bc at freeuk.com (BartC)
Date: Sun, 22 Nov 2015 13:21:02 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2sfbh$l8f$1@dont-email.me>

On 22/11/2015 03:43, Steven D'Aprano wrote:
> On Fri, 20 Nov 2015 10:59 pm, BartC wrote:
>
>> On 20/11/2015 01:05, Steven D'Aprano wrote:
>
>>> Here's another use for function defaults, as static storage:
> [...]
>>> This is a quick and easy way to memoise a function which would otherwise
>>> be horribly slow. And it only works because _memo is bound to a mutable
>>> object once, and once only.
>>
>> We're arguing at cross-purposes then since you are obviously interested
>> in these esoteric aspects,
>
> Memoisation isn't "esoteric", it is a simple, basic and widely-used
> technique used to improve performance of otherwise expensive functions.

Ackermann is esoteric and so is memoisation, or at least the term is.

(I use the Ackermann function frequently, but usually as a benchmark 
measuring how good a language implementation is at function calls, 
especially recursive ones. And how well it copes with large recursion 
depth. Adding memoisation would defeat the purpose!)

But if it's used for static storage, then why not just use static 
storage? That's a simpler and more general concept than memoisation.

If Python's 'default values' are just a device for obtaining local 
static storage which are otherwise not possible, then why not use 
terminology to say so? As I guess it's too late to do anything about the 
syntax.

(Of course it won't be quite the same, as the caller can overwrite the 
local and /private/ 'static' variables at any time, but I suppose that 
would be yet another feature!)

> Quite frankly, to call it such demonstrates a considerable level of
> ignorance about basic programming idioms. Not just Python, but general
> purpose programming.

I've come to learn that basic idioms are best. Especially trying to 
understand someone else's code (or to translate into another language 
with a different set of advanced features). Some people delight in 
pulling out all the stops and using all the advanced features of a 
language to the hilt. With the result being very concise and clever 
code, but completely unreadable.

>> (Here, however, the language doesn't like you doing in-place
>> modification of a parameter unless the '&' is used,

> It sounds to me like you have implemented something like Pascal's "var"
> parameters, is that right? I believe some languages (VB perhaps?) call
> them "output parameters".

(Something like that. Python seems to exclusively to push around 
references to objects. I use a mix of value objects and part-references. 
The & is an indication to use full references. I can also use actual 
pointers, but I'm trying to get away from that.)

>> OK, so the "=" is misleading if not a lie.
>
> No. Why would you conclude that? If I called the function like so:
>
>      test( [1, 2, 3, 4, 5] )
>
> and got the result 6, would I conclude that the "=" is misleading if not a
> lie? After all, the function declaration clearly shows arg being assigned
> the value [], so why am I getting 6 as the result instead of 1?

That's being silly. We all know this is default value syntax. The lie is 
the [] not necessarily being the default value on every call.

> The whole point of parameter default arguments is that they are bound to the
> parameter *only* if the parameter otherwise isn't given a value. That's a
> separate issue from *when* the default expression is evaluated.

No, that is at the heart of matter. And it's not just a question of 
'when' the 'binding' is done, but the fact that, even if we accept that 
the default value is evaluated when the function is defined, that value 
can then subsequently change.

We all know now /why/ it can do so, which is an unfortunate consequence 
of how it's implemented. But you seem very keen to show it in a positive 
light. It's a feature, not a bug!

>> In my language, a construct such as [10,20,30] is evaluated just once at
>> start-up.
>
> I don't understand that explanation. How does that work? Given:
>
> x = [10, 20, 30]
> y = [10, 20, 30]
>
>
> how does your language know what value y has if it doesn't evaluate the
> second construct?

(It generates some start-up code which assigns [10,20,30] to a variable. 
Then that variable is used in place of that particular [10,20,30]. (It 
doesn't combine multiple instances of the same constant list, as that is 
not common. So y would be dealt with separately.)

I think Python already does something along these lines for tuples, 
which cannot change. It means you're executing a simple LOAD instead of 
BUILT_LIST on N values.)

-- 
Bartc


From me at sntsh.com  Sun Nov 22 08:25:29 2015
From: me at sntsh.com (Santosh Kumar)
Date: Sun, 22 Nov 2015 18:55:29 +0530
Subject: How to remember last position and size (geometry) of PyQt application?
Message-ID: <CAE7MaQZj=smhVjxBzv2osAYEL8wVGbiwB3LJ2sPDx2trNWPUaA@mail.gmail.com>

Hello all fellow Python programmers!

I am using PyQt5 (5.5.1) with Python 3.4.0 (64-bit) on Windows 8.1
64-bit. I don't think this much data was needed. :P

I am having trouble restoring the position and size (geometry) of my
very simple PyQt app.

What I read online is that this is the default behavior and we need to
use QSettings to save and retrieve settings from Windows registry,
which is stored in
`\\HKEY_CURRENT_USER\Software\[CompanyName]\[AppName]\`.

Here are some of the links are read:
http://doc.qt.io/qt-5.5/restoring-geometry.html
http://doc.qt.io/qt-5.5/qwidget.html#saveGeometry
http://doc.qt.io/qt-5.5/qsettings.html#restoring-the-state-of-a-gui-application
and the last one:
https://ic3man5.wordpress.com/2013/01/26/save-qt-window-size-and-state-on-closeopen/

I could have followed those tutorials but those tutorials/docs were
written for C++ users.

C++ is not my glass of beer. Should I expect help from you guys? :)

Here is minimal working application:


import sys
from PyQt5.QtWidgets import QApplication, QWidget

class sViewer(QWidget):
    """Main class of sViewer"""
    def __init__(self):
        super(sViewer, self).__init__()
        self.initUI()


    def initUI(self):
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    view = sViewer()
    sys.exit(app.exec_())


From bc at freeuk.com  Sun Nov 22 09:28:34 2015
From: bc at freeuk.com (BartC)
Date: Sun, 22 Nov 2015 14:28:34 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <n2sfbh$l8f$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
Message-ID: <n2sja5$44m$1@dont-email.me>

On 22/11/2015 13:21, BartC wrote:
> On 22/11/2015 03:43, Steven D'Aprano wrote:

>> Quite frankly, to call it such demonstrates a considerable level of
>> ignorance about basic programming idioms. Not just Python, but general
>> purpose programming.
>
> I've come to learn that basic idioms are best.

I may have misunderstood what you meant by 'basic idioms' here. It seems 
we disagree as to what is 'basic'.

-- 
bartc


From gordon at panix.com  Sun Nov 22 11:39:08 2015
From: gordon at panix.com (John Gordon)
Date: Sun, 22 Nov 2015 16:39:08 +0000 (UTC)
Subject: anyone tell me why my program will not run?
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
Message-ID: <n2sr3c$50c$1@reader1.panix.com>

In <1737402a-2f4d-440a-abd7-6cc500f673e1 at googlegroups.com> Dylan Riley <dylan.riley at hotmail.com> writes:

> heads = int("1")

Why are you taking the int value of a string constant?  If you know you
want the value 1, why not just use it directly?

> flips = 100
> headscount = 0
> tailscount = 0

> while flips != 0:
>     flips -= 1

This loop has no other effect than to set flips to zero, so why not just
set flips to zero in the first place?

> result = random.randint(heads, tails)
> if result = heads:
>     headscount += 1
> else:
>     tailscount += 1

Perhaps you meant to have this piece of code indented under the while
loop above?

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From orgnut at yahoo.com  Sun Nov 22 16:42:20 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Sun, 22 Nov 2015 13:42:20 -0800
Subject: anyone tell me why my program will not run?
In-Reply-To: <dr2dnegom5afsczLnZ2dnUU7-bmdnZ2d@giganews.com>
References: <1737402a-2f4d-440a-abd7-6cc500f673e1@googlegroups.com>
 <dr2dnegom5afsczLnZ2dnUU7-bmdnZ2d@giganews.com>
Message-ID: <PK2dnbXexawgq8_LnZ2dnUU7-dmdnZ2d@giganews.com>

On 11/21/2015 06:44 PM, Larry Hudson wrote:
> On 11/20/2015 07:30 PM, Dylan Riley wrote:
>> i am learning python and was tasked with making a program that flips a coin 100 times and then
>> tells you
>> the number of heads and tails.
>>
[snip]
<original code>
>> import random
>>
>> heads = int("1")
>> tails = int("2")
>> flips = 100
>> headscount = 0
>> tailscount = 0
>>
>> while flips != 0:
>>      flips -= 1
>>
>> result = random.randint(heads, tails)
>> if result = heads:
>>      headscount += 1
>> else:
>>      tailscount += 1
>>
>>
>> print(headscount, tailscount)
[snip]
</original code>

> It doesn't run because it if full of errors, which have already been discussed by others.
>
> I just wanted to show you a (radically) different approach that you can study (or not... your
> choice).  I'm leaving out your heading and just showing the heart of the program.  I am not
> necessarily recommending this, I just wanted you to see a different way of looking at the
> problem.  Except for the initialization and printing of the results, the entire thing is done in
> one two-line for loop.
>
> <code>
> from random import randint
>
> #  Put your heading text here...
>
> HEADS = 0
> TAILS = 1    #  Note:  Python _convention_ is to upper-case constants.
> counts = [0, 0]
>
> for flips in range(100):
>      counts[randint(0, 1)] += 1
>
> print('Number of heads: ', counts[HEADS])
> print('Number of tails: ', counts[TAILS])
> </code>
>
> Note that the HEADS and TAILS constants are only used in one place (the final print functions),
> you could simply leave them out and directly use 0 and 1 in those final print()s.
>
>       -=- Larry -=-
>

I purposely didn't give any explanation of this code in my original message because I wanted to 
allow people (particularly the OP) a chance to figure it out by themselves. But here's a bit of 
explanation...

The counts variable is a two-element list. It's usage is, the count of heads is counts[0] and 
the count of tails is counts[1] -- or equivalently, counts[HEADS] and counts[TAILS]. Both values 
are initialized to 0.

The body of the for loop is the very terse (and confusing?) expression:
     counts[randint(0, 1)] += 1

But if you break it down and look at the pieces individually, it's not too hard to understand.
1. randint(0, 1) gives a random value of either 0 or 1.
2. counts[...] gives you access to the heads count or tails count (... is the 0 or 1 from the 
randint() function).
3. counts[...] += 1 increments the appropriate counter value.

Broken down that way it?s not too hard to understand, is it?   :-)

-=- Larry -=-



From rosuav at gmail.com  Sun Nov 22 17:12:01 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 23 Nov 2015 09:12:01 +1100
Subject: Comparators
In-Reply-To: <SWq4y.489752$6i2.36058@fx35.am4>
References: <da205c85-b569-47a6-9708-8cd7d6c5205e@googlegroups.com>
 <slrnn51roe.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <e686b079-0e22-4ee9-a8a0-b46b159bf7f7@googlegroups.com>
 <mailman.45.1448146861.2291.python-list@python.org>
 <SWq4y.489752$6i2.36058@fx35.am4>
Message-ID: <CAPTjJmpKgn=jX_bgH10WZ1ccyWiDN1Xt6Rg74VLAUz592a_ymQ@mail.gmail.com>

On Mon, Nov 23, 2015 at 9:01 AM, Quivis <quivis at domain.invalid> wrote:
> On Sun, 22 Nov 2015 10:00:51 +1100, Chris Angelico wrote:
>
>> I recommend creating a text file of notes. Every time you learn
>> something new, add it to your notes file - and commit the change to git.
>> Then, when you come back to the file, you'll have one of several
>> reactions:
>
> The git part is good advice. I'd like to build on your idea, though.
>
> Create a directory of small text files, each containing a solution to a
> problem, with comments, and what not.
>
> When you look for something, do:
>
>     grep 'the stuff I look for' *

I'm not sure the advantage of splitting the files, but yeah, same
difference. Keep notes, one way or another.

ChrisA


From greg.ewing at canterbury.ac.nz  Sun Nov 22 18:30:02 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 23 Nov 2015 12:30:02 +1300
Subject: What is a function parameter =[] for?
In-Reply-To: <n2n46v$uj0$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
Message-ID: <dbf1fsFo8teU1@mid.individual.net>

BartC wrote:
> What's bothering me is:
> 
> ...
> 
> * The insistence (I think largely from Steven) that the way this feature 
> works is good rather than bad

Here's one reason to prefer the way it currently works:

It's rare to want a mutable default value. The vast
majority of default values are simple things such as
None, 0 or "". Evaluating the default expression on
every call in those cases would just be useless
overhead. So Python optimises for the most common
case. When you need a mutable default, there is a
straightforward way to get it.

-- 
Greg


From greg.ewing at canterbury.ac.nz  Sun Nov 22 18:43:52 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Mon, 23 Nov 2015 12:43:52 +1300
Subject: What is a function parameter =[] for?
In-Reply-To: <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <dbf29qFoem0U1@mid.individual.net>

Steven D'Aprano wrote:
> Memoisation isn't "esoteric", it is a simple, basic and widely-used
> technique used to improve performance of otherwise expensive functions.

That may be true, but I don't think it's a good example
of a use for a shared, mutable default value, because
it's arguably an *abuse* of the default value mechanism.

Whenever I want to cache function values, I use a module
level variable to hold the cache. It's clearer, and it
doesn't clutter the function signature with something
that isn't logically a part of it at all.

-- 
Greg


From steve at pearwood.info  Sun Nov 22 18:44:24 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Mon, 23 Nov 2015 10:44:24 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
Message-ID: <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>

On Mon, 23 Nov 2015 12:21 am, BartC wrote:

> But if it's used for static storage, then why not just use static
> storage? That's a simpler and more general concept than memoisation.

/head-desk

"But if it's used for cooking, why not just cook? That's a simpler and more
general concept than roasting."



-- 
Steven



From breamoreboy at yahoo.co.uk  Sun Nov 22 19:04:52 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 23 Nov 2015 00:04:52 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2tl76$1kr$1@ger.gmane.org>

On 22/11/2015 23:44, Steven D'Aprano wrote:
> On Mon, 23 Nov 2015 12:21 am, BartC wrote:
>
>> But if it's used for static storage, then why not just use static
>> storage? That's a simpler and more general concept than memoisation.
>
> /head-desk
>
> "But if it's used for cooking, why not just cook? That's a simpler and more
> general concept than roasting."
>

What happened to "Please do not feed the trolls"?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From joel.goldstick at gmail.com  Sun Nov 22 19:08:50 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sun, 22 Nov 2015 19:08:50 -0500
Subject: Is there an meaning of '[[]]' in a list?
In-Reply-To: <V9s4y.489754$6i2.102301@fx35.am4>
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
 <mailman.454.1447933236.16136.python-list@python.org>
 <V9s4y.489754$6i2.102301@fx35.am4>
Message-ID: <CAPM-O+w17fqu7Z8NVrdooeqnSKDgbH98xtmpDxDuZ03pnEgAVA@mail.gmail.com>

On Sun, Nov 22, 2015 at 6:25 PM, Quivis <quivis at domain.invalid> wrote:

> On Thu, 19 Nov 2015 12:40:17 +0100, Peter Otten wrote:
>
> > those questions that are a little harder
>
> And just how is he going to determine what is hard?
> --
>   _____  __ __ __ __ __ __   __
>  ((   )) || || || \\ // ||  ((
>   \\_/X| \\_// ||  \V/  || \_))
>    Omnia paratus  *~*~*~*~*~*~*
> --
> https://mail.python.org/mailman/listinfo/python-list
>

from the OP:
Hi,
In the previous exercises, I see list:
cc=[[],[],[]]

This seems to refer to some tutorial maybe?

I suppose there could be some value in an exercise like this, but I don't
see it.

-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From rosuav at gmail.com  Sun Nov 22 19:20:34 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 23 Nov 2015 11:20:34 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2tl76$1kr$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <n2tl76$1kr$1@ger.gmane.org>
Message-ID: <CAPTjJmprWkswUMGnhwd28-gfEuv-FKYQtPnKdMKUedbXMXtS8w@mail.gmail.com>

On Mon, Nov 23, 2015 at 11:04 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> What happened to "Please do not feed the trolls"?

Hey, Norwegian researchers get hungry too you know!

https://en.wikipedia.org/wiki/Troll_(research_station)

ChrisA


From bc at freeuk.com  Sun Nov 22 19:37:32 2015
From: bc at freeuk.com (BartC)
Date: Mon, 23 Nov 2015 00:37:32 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.55.1448237105.2291.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <mailman.55.1448237105.2291.python-list@python.org>
Message-ID: <n2tn01$ko3$1@dont-email.me>

On 23/11/2015 00:04, Mark Lawrence wrote:
> On 22/11/2015 23:44, Steven D'Aprano wrote:
>> On Mon, 23 Nov 2015 12:21 am, BartC wrote:
>>
>>> But if it's used for static storage, then why not just use static
>>> storage? That's a simpler and more general concept than memoisation.
>>
>> /head-desk
>>
>> "But if it's used for cooking, why not just cook? That's a simpler and
>> more
>> general concept than roasting."

With 'it' being a washing machine perhaps? But I'll let this other chap 
have the last word as he puts it across better:

 > Steven D'Aprano wrote:
 >> Memoisation isn't "esoteric", it is a simple, basic and widely-used
 >> technique used to improve performance of otherwise expensive functions.

On 22/11/2015 23:43, Gregory Ewing wrote:

 > That may be true, but I don't think it's a good example
 > of a use for a shared, mutable default value, because
 > it's arguably an *abuse* of the default value mechanism.

> What happened to "Please do not feed the trolls"?

You mean, people with different opinions?

I think I'm done here.

-- 
Bartc





From chris at simplistix.co.uk  Mon Nov 23 01:46:35 2015
From: chris at simplistix.co.uk (Chris Withers)
Date: Mon, 23 Nov 2015 06:46:35 +0000
Subject: testfixtures 4.5.1 Released!
Message-ID: <5652B64B.1080804@simplistix.co.uk>

Hi All,

I'm pleased to announce the release of testfixtures 4.5.1. This release 
that contains:

- LogCapture, OutputCapture and TempDirectory
   explicitly show what is expected versus actual when reporting
   differences as of 4.5.0.

- The 4.5.1 release contains a bugfix where OutputCapture couldn't
   handle capturing unicode.

Thanks to Daniel Fortunov for the expected vs actual changes.

Thanks to "tell-k" for the bugfix.

The package is on PyPI and a full list of all the links to docs, issue 
trackers and the like can be found here:

https://github.com/Simplistix/testfixtures

Any questions, please do ask on the Testing in Python list or on the 
Simplistix open source mailing list...

cheers,

Chris

-- 
Simplistix - Content Management, Batch Processing & Python Consulting
            - http://www.simplistix.co.uk


From larry at hastings.org  Mon Nov 23 02:16:44 2015
From: larry at hastings.org (Larry Hastings)
Date: Sun, 22 Nov 2015 23:16:44 -0800
Subject: [RELEASED] Python 3.5.1rc1 is now available
Message-ID: <5652BD5C.6040107@hastings.org>


On behalf of the Python development community and the Python 3.5 release 
team, I'm pleased to announce the availability of Python 3.5.1rc1.  
Python 3.5.1 will be the first update for Python 3.5.  Python 3.5 is the 
newest version of the Python language, and it contains many exciting new 
features and optimizations.


You can see what's changed in Python 3.5.1rc1 (as compared to 3.5.0) here:

    https://docs.python.org/3.5/whatsnew/changelog.html


And you can download Python 3.5.1 here:

    https://www.python.org/downloads/release/python-351rc1/

Windows and Mac users: please read the important platform-specific 
"Notes on this release" section near the end of that page.



We hope you enjoy Python 3.5.1!


//arry/


From steve+comp.lang.python at pearwood.info  Mon Nov 23 02:47:52 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Mon, 23 Nov 2015 18:47:52 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <dbf29qFoem0U1@mid.individual.net>
Message-ID: <5652c4ac$0$1621$c3e8da3$5496439d@news.astraweb.com>

On Monday 23 November 2015 10:43, Gregory Ewing wrote:

> Steven D'Aprano wrote:
>> Memoisation isn't "esoteric", it is a simple, basic and widely-used
>> technique used to improve performance of otherwise expensive functions.
> 
> That may be true, but I don't think it's a good example
> of a use for a shared, mutable default value, because
> it's arguably an *abuse* of the default value mechanism.
> 
> Whenever I want to cache function values, I use a module
> level variable to hold the cache. It's clearer, and it
> doesn't clutter the function signature with something
> that isn't logically a part of it at all.

Neither solution is really fantastic, but they both get the job done.

Module level global caches have all the disadvantages of global variables. 
You need a unique name for each function that uses one, it breaks 
encapsulation, and it leaves you at the mercy of any code which modifies the 
global.

But I agree that having the cache in the function signature is a bit smelly. 
But smelly or not, it works well enough for a quick and dirty cache, and 
using the function parameter list to initialise static local variables is a 
moderately common thing to do. For example:

help(random.randrange)

Help on method randrange in module random:

randrange(self, start, stop=None, step=1, int=<type 'int'>, default=None, 
maxwidth=9007199254740992L) method of random.Random instance
    Choose a random item from range(start, stop[, step]).


I think it would be cleaner and better if Python had dedicated syntax for 
declaring static local variables:

def randrange(self, start, stop=None, step=1):
    static int=type(1), default=None, maxwidth=9007199254740992L
    ...


def func(a, b):
    static cache = {}
    ...


Another good example of using a default mutable argument comes from Guido 
himself:

https://www.python.org/doc/essays/graphs/

Note that the use of a mutable default is perfectly safe, because the 
default is never modified.


-- 
Steve


From Cecil at decebal.nl  Mon Nov 23 02:48:54 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 23 Nov 2015 08:48:54 +0100
Subject: pip does not work anymore
Message-ID: <87vb8trw9l.fsf@Equus.decebal.nl>

When I try to install something with pip2 I get:
    Traceback (most recent call last):
      File "/usr/bin/pip2", line 9, in <module>
        load_entry_point('pip==7.1.2', 'console_scripts', 'pip2')()
      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 558, in load_entry_point
        return get_distribution(dist).load_entry_point(group, name)
      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2682, in load_entry_point
        return ep.load()
      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2355, in load
        return self.resolve()
      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2361, in resolve
        module = __import__(self.module_name, fromlist=['__name__'], level=0)
      File "/usr/lib/python2.7/site-packages/pip/__init__.py", line 15, in <module>
        from pip.vcs import git, mercurial, subversion, bazaar  # noqa
      File "/usr/lib/python2.7/site-packages/pip/vcs/subversion.py", line 9, in <module>
        from pip.index import Link
      File "/usr/lib/python2.7/site-packages/pip/index.py", line 30, in <module>
        from pip.wheel import Wheel, wheel_ext
      File "/usr/lib/python2.7/site-packages/pip/wheel.py", line 35, in <module>
        from pip._vendor.distlib.scripts import ScriptMaker
      File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 14, in <module>
        from .compat import sysconfig, detect_encoding, ZipFile
      File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/compat.py", line 31, in <module>
        from urllib2 import (Request, urlopen, URLError, HTTPError,
    ImportError: cannot import name HTTPSHandler

With pip3 I get the same problem.

It looks like openSUSE has done an upgrade in which it disabled ssl2.
How can I get pip2/3 working again?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From lac at openend.se  Mon Nov 23 03:11:46 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 23 Nov 2015 09:11:46 +0100
Subject: pip does not work anymore
In-Reply-To: <87vb8trw9l.fsf@Equus.decebal.nl>
References: <87vb8trw9l.fsf@Equus.decebal.nl>
Message-ID: <201511230811.tAN8Bk1n009770@fido.openend.se>

In a message of Mon, 23 Nov 2015 08:48:54 +0100, Cecil Westerhof writes:
>When I try to install something with pip2 I get:
>    Traceback (most recent call last):
>      File "/usr/bin/pip2", line 9, in <module>
>        load_entry_point('pip==7.1.2', 'console_scripts', 'pip2')()
>      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 558, in load_entry_point
>        return get_distribution(dist).load_entry_point(group, name)
>      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2682, in load_entry_point
>        return ep.load()
>      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2355, in load
>        return self.resolve()
>      File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2361, in resolve
>        module = __import__(self.module_name, fromlist=['__name__'], level=0)
>      File "/usr/lib/python2.7/site-packages/pip/__init__.py", line 15, in <module>
>        from pip.vcs import git, mercurial, subversion, bazaar  # noqa
>      File "/usr/lib/python2.7/site-packages/pip/vcs/subversion.py", line 9, in <module>
>        from pip.index import Link
>      File "/usr/lib/python2.7/site-packages/pip/index.py", line 30, in <module>
>        from pip.wheel import Wheel, wheel_ext
>      File "/usr/lib/python2.7/site-packages/pip/wheel.py", line 35, in <module>
>        from pip._vendor.distlib.scripts import ScriptMaker
>      File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 14, in <module>
>        from .compat import sysconfig, detect_encoding, ZipFile
>      File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/compat.py", line 31, in <module>
>        from urllib2 import (Request, urlopen, URLError, HTTPError,
>    ImportError: cannot import name HTTPSHandler
>
>With pip3 I get the same problem.
>
>It looks like openSUSE has done an upgrade in which it disabled ssl2.
>How can I get pip2/3 working again?
>
>-- 
>Cecil Westerhof
>Senior Software Engineer
>LinkedIn: http://www.linkedin.com/in/cecilwesterhof
>-- 
>https://mail.python.org/mailman/listinfo/python-list

Reading https://forums.opensuse.org/showthread.php/488962-OpenSuse-python-amp-openssl
seems to indicatew that you are supposed to use python-pip and not pip
for OpenSuse, but I don't have one, so that is just my interpretation.

Laura


From rosuav at gmail.com  Mon Nov 23 03:23:54 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 23 Nov 2015 19:23:54 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
Message-ID: <CAPTjJmrWnMPhEY8wmV0dzdMjfDJPAj0oArpt1d+h0B5uw3wzsA@mail.gmail.com>

On Fri, Nov 20, 2015 at 6:46 AM, Chris Angelico <rosuav at gmail.com> wrote:
> The expressions would be evaluated as closures, using the same scope
> that the function's own definition used. (This won't keep things alive
> unnecessarily, as the function's body will be nested within that same
> scope anyway.) Bikeshed the syntax all you like, but this would be
> something to point people to: "here's how to get late-binding
> semantics". For the purposes of documentation, the exact text of the
> parameter definition could be retained, and like docstrings, they
> could be discarded in -OO mode.

Just out of interest, I had a shot at implementing this with a
decorator. Here's the code:

# -- cut --

import functools
import time

class lb:
    def __repr__(self): return "<late-bind>"

def latearg(f):
    tot_args = f.__code__.co_argcount
    min_args = tot_args - len(f.__defaults__)
    defs = f.__defaults__
    # With compiler help, we could get the original text as well as something
    # executable that works in the correct scope. Without compiler help, we
    # either use a lambda function, or an exec/eval monstrosity that can't use
    # the scope of its notional definition (since its *actual* definition will
    # be inside this decorator). Instead, just show a fixed bit of text.
    f.__defaults__ = tuple(lb() if callable(arg) else arg for arg in defs)
    @functools.wraps(f)
    def inner(*a,**kw):
        if len(a) < min_args: return f(*a, **kw) # Will trigger TypeError
        if len(a) < tot_args:
            more_args = defs[len(a)-tot_args:]
            a += tuple(arg() if callable(arg) else arg for arg in more_args)
        return f(*a,**kw)
    return inner

def sleeper(tm):
    """An expensive function."""
    t = time.monotonic()
    time.sleep(tm)
    return time.monotonic() - t - tm

seen_args = []
@latearg
def foo(spam, ham=lambda: [], val=lambda: sleeper(0.5)):
    print("%s: Ham %X with sleeper %s" % (spam, id(ham), val))
    seen_args.append(ham) # Keep all ham objects alive so IDs are unique

@latearg
def x(y=lambda: []):
    y.append(1)
    return y

print("Starting!")
foo("one-arg 1")
foo("one-arg 2")
foo("two-arg 1", [])
foo("two-arg 2", [])
foo("tri-arg 1", [], 0.0)
foo("tri-arg 2", [], 0.0)
print(x())
print(x())
print(x())
print(x([2]))
print(x([3]))
print(x([4]))
print("Done!")

# -- cut --


This does implement late binding, but:
1) The adornment is the rather verbose "lambda:", where I'd much
rather have something shorter
2) Since there's no way to recognize "the ones that were adorned", the
decorator checks for "anything callable"
3) Keyword args aren't handled - they're passed through as-is (and
keyword-only arg defaults aren't rendered)
4) As commented, the help text can't pick up the text of the function

But it does manage to render args at execution time, and the help()
for the function identifies the individual arguments correctly (thanks
to functools.wraps and the modified defaults - though this
implementation is a little unfriendly, mangling the original function
defaults instead of properly wrapping).

Clock this one up as "useless code that was fun to write".

ChrisA


From __peter__ at web.de  Mon Nov 23 03:57:36 2015
From: __peter__ at web.de (Peter Otten)
Date: Mon, 23 Nov 2015 09:57:36 +0100
Subject: Is there an meaning of '[[]]' in a list?
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
 <mailman.454.1447933236.16136.python-list@python.org>
 <V9s4y.489754$6i2.102301@fx35.am4>
Message-ID: <n2uke1$8qm$1@ger.gmane.org>

Quivis wrote:

> On Thu, 19 Nov 2015 12:40:17 +0100, Peter Otten wrote:
> 
>> those questions that are a little harder
> 
> And just how is he going to determine what is hard?

Note that I said "a little harder", not "hard".

Write down your next ten or so questions, then work through the tutorial or 
another introductory text, then use a search engine, then post the one or 
two questions that are still unanswered.




From Cecil at decebal.nl  Mon Nov 23 04:33:18 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 23 Nov 2015 10:33:18 +0100
Subject: pip does not work anymore
References: <87vb8trw9l.fsf@Equus.decebal.nl>
 <mailman.60.1448266316.2291.python-list@python.org>
Message-ID: <87r3jhrrfl.fsf@Equus.decebal.nl>

On Monday 23 Nov 2015 09:11 CET, Laura Creighton wrote:

> In a message of Mon, 23 Nov 2015 08:48:54 +0100, Cecil Westerhof
> writes:
>> When I try to install something with pip2 I get: Traceback (most
>> recent call last): File "/usr/bin/pip2", line 9, in <module>
>> load_entry_point('pip==7.1.2', 'console_scripts', 'pip2')() File
>> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
>> 558, in load_entry_point return
>> get_distribution(dist).load_entry_point(group, name) File
>> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
>> 2682, in load_entry_point return ep.load() File
>> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
>> 2355, in load return self.resolve() File
>> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
>> 2361, in resolve module = __import__(self.module_name,
>> fromlist=['__name__'], level=0) File
>> "/usr/lib/python2.7/site-packages/pip/__init__.py", line 15, in
>> <module> from pip.vcs import git, mercurial, subversion, bazaar #
>> noqa File "/usr/lib/python2.7/site-packages/pip/vcs/subversion.py",
>> line 9, in <module> from pip.index import Link File
>> "/usr/lib/python2.7/site-packages/pip/index.py", line 30, in
>> <module> from pip.wheel import Wheel, wheel_ext File
>> "/usr/lib/python2.7/site-packages/pip/wheel.py", line 35, in
>> <module> from pip._vendor.distlib.scripts import ScriptMaker File
>> "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py",
>> line 14, in <module> from .compat import sysconfig,
>> detect_encoding, ZipFile File
>> "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/compat.py",
>> line 31, in <module> from urllib2 import (Request, urlopen,
>> URLError, HTTPError, ImportError: cannot import name HTTPSHandler
>>
>> With pip3 I get the same problem.
>>
>> It looks like openSUSE has done an upgrade in which it disabled
>> ssl2. How can I get pip2/3 working again?
>>
>
> Reading
> https://forums.opensuse.org/showthread.php/488962-OpenSuse-python-amp-openssl
> seems to indicatew that you are supposed to use python-pip and not
> pip for OpenSuse, but I don't have one, so that is just my
> interpretation.

python-pip is the package that you need to install to use pip2. I
removed it and then pip2 does not exist anymore. I reinstalled it, but
keep getting the same error. It looks like I need to install:
    https://docs.python.org/2/library/urllib2.html?highlight=urllib2#urllib2.HTTPSHandler
but I need pip2 to do that. So I need a working pip2 to get it
working. :'-(


By the way openSUSE did a big update and broke other things also. For
example virtualbox. Probably time to really leave openSUSE for Debian.
But that will not be painless.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From gengyangcai at gmail.com  Mon Nov 23 04:55:11 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Mon, 23 Nov 2015 01:55:11 -0800 (PST)
Subject: Creating a Dynamic Website Using Python
Message-ID: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>

Ok, 

So I have gone through the CodeAcademy Python modules and decided to jump straight into a project. 

I want to create a dynamic web-based site like this --- https://www.wedpics.com using Python 

How / where do I start ?

Thanks a lot !

Gengyang 


From bc at freeuk.com  Mon Nov 23 05:40:41 2015
From: bc at freeuk.com (BartC)
Date: Mon, 23 Nov 2015 10:40:41 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <5652c4ac$0$1621$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <dbf29qFoem0U1@mid.individual.net>
 <5652c4ac$0$1621$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n2uqau$mme$1@dont-email.me>

On 23/11/2015 07:47, Steven D'Aprano wrote:

> I think it would be cleaner and better if Python had dedicated syntax for
> declaring static local variables:

Interesting. So why is it that when /I/ said:

 > On Mon, 23 Nov 2015 12:21 am, BartC wrote:
 >
 >> But if it's used for static storage, then why not just use static
 >> storage?

You replied with the insulting:

 > /head-desk

?

Maybe it's my turn to bang my head on the desk.

-- 
Bartc



From Cecil at decebal.nl  Mon Nov 23 06:14:11 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 23 Nov 2015 12:14:11 +0100
Subject: pip does not work anymore
References: <87vb8trw9l.fsf@Equus.decebal.nl>
Message-ID: <8737vxrmrg.fsf@Equus.decebal.nl>

On Monday 23 Nov 2015 08:48 CET, Cecil Westerhof wrote:

> When I try to install something with pip2 I get: Traceback (most
> recent call last): File "/usr/bin/pip2", line 9, in <module>
> load_entry_point('pip==7.1.2', 'console_scripts', 'pip2')() File
> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
> 558, in load_entry_point return
> get_distribution(dist).load_entry_point(group, name) File
> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
> 2682, in load_entry_point return ep.load() File
> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
> 2355, in load return self.resolve() File
> "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line
> 2361, in resolve module = __import__(self.module_name,
> fromlist=['__name__'], level=0) File
> "/usr/lib/python2.7/site-packages/pip/__init__.py", line 15, in
> <module> from pip.vcs import git, mercurial, subversion, bazaar #
> noqa File "/usr/lib/python2.7/site-packages/pip/vcs/subversion.py",
> line 9, in <module> from pip.index import Link File
> "/usr/lib/python2.7/site-packages/pip/index.py", line 30, in
> <module> from pip.wheel import Wheel, wheel_ext File
> "/usr/lib/python2.7/site-packages/pip/wheel.py", line 35, in
> <module> from pip._vendor.distlib.scripts import ScriptMaker File
> "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py",
> line 14, in <module> from .compat import sysconfig, detect_encoding,
> ZipFile File
> "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/compat.py",
> line 31, in <module> from urllib2 import (Request, urlopen,
> URLError, HTTPError, ImportError: cannot import name HTTPSHandler
>
> With pip3 I get the same problem.
>
> It looks like openSUSE has done an upgrade in which it disabled
> ssl2. How can I get pip2/3 working again?

Can I make pip work with ssl3?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From Cecil at decebal.nl  Mon Nov 23 06:16:49 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 23 Nov 2015 12:16:49 +0100
Subject: Let urllib3 use ssl3 instead of ssl2
Message-ID: <87y4dpq82m.fsf@Equus.decebal.nl>

For a program I need to import urllib3, but this gives:
    ImportError: /usr/lib64/python2.7/lib-dynload/_ssl.so: undefined symbol: SSLv2_method

This probably has to do with that openSUSE removed ssl2 because it is
not secure. Is there a way to let urllib3 use ssl3 instead of ssl2?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From breamoreboy at yahoo.co.uk  Mon Nov 23 06:31:10 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 23 Nov 2015 11:31:10 +0000
Subject: Creating a Dynamic Website Using Python
In-Reply-To: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>
References: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>
Message-ID: <n2utdv$hnk$1@ger.gmane.org>

On 23/11/2015 09:55, Cai Gengyang wrote:
> Ok,
>
> So I have gone through the CodeAcademy Python modules and decided to jump straight into a project.
>
> I want to create a dynamic web-based site like this --- https://www.wedpics.com using Python
>
> How / where do I start ?
>

With a search engine, or do you need instructions on how to use one?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From breamoreboy at yahoo.co.uk  Mon Nov 23 06:32:47 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Mon, 23 Nov 2015 11:32:47 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <n2tn01$ko3$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <mailman.55.1448237105.2291.python-list@python.org>
 <n2tn01$ko3$1@dont-email.me>
Message-ID: <n2uth0$hnk$2@ger.gmane.org>

On 23/11/2015 00:37, BartC wrote:
> On 23/11/2015 00:04, Mark Lawrence wrote:
>> On 22/11/2015 23:44, Steven D'Aprano wrote:
>>> On Mon, 23 Nov 2015 12:21 am, BartC wrote:
>>>
>>>> But if it's used for static storage, then why not just use static
>>>> storage? That's a simpler and more general concept than memoisation.
>>>
>>> /head-desk
>>>
>>> "But if it's used for cooking, why not just cook? That's a simpler and
>>> more
>>> general concept than roasting."
>
> With 'it' being a washing machine perhaps? But I'll let this other chap
> have the last word as he puts it across better:
>
>  > Steven D'Aprano wrote:
>  >> Memoisation isn't "esoteric", it is a simple, basic and widely-used
>  >> technique used to improve performance of otherwise expensive functions.
>
> On 22/11/2015 23:43, Gregory Ewing wrote:
>
>  > That may be true, but I don't think it's a good example
>  > of a use for a shared, mutable default value, because
>  > it's arguably an *abuse* of the default value mechanism.
>
>> What happened to "Please do not feed the trolls"?
>
> You mean, people with different opinions?
>
> I think I'm done here.
>

Wow, so there is a God.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From ned at nedbatchelder.com  Mon Nov 23 07:05:52 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Mon, 23 Nov 2015 04:05:52 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.64.1448278522.2291.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <mailman.55.1448237105.2291.python-list@python.org>
 <n2tn01$ko3$1@dont-email.me>
 <mailman.64.1448278522.2291.python-list@python.org>
Message-ID: <750e8337-ce14-4a72-b016-ab326424965d@googlegroups.com>

On Monday, November 23, 2015 at 6:35:35 AM UTC-5, Mark Lawrence wrote:
> On 23/11/2015 00:37, BartC wrote:
> > On 23/11/2015 00:04, Mark Lawrence wrote:
> >> What happened to "Please do not feed the trolls"?
> >
> > You mean, people with different opinions?
> >
> > I think I'm done here.
> >
> 
> Wow, so there is a God.

Mark, you aren't helping.

--Ned.


From rosuav at gmail.com  Mon Nov 23 07:21:02 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 23 Nov 2015 23:21:02 +1100
Subject: Creating a Dynamic Website Using Python
In-Reply-To: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>
References: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>
Message-ID: <CAPTjJmoKQNamgVuVu1XNTRq71pyG9XF7nV4qT2qd8=3vQFzKVg@mail.gmail.com>

On Mon, Nov 23, 2015 at 8:55 PM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> So I have gone through the CodeAcademy Python modules and decided to jump straight into a project.
>
> I want to create a dynamic web-based site like this --- https://www.wedpics.com using Python
>
> How / where do I start ?

While it's *possible* to create a web site using just a base Python
install, it's a lot more work than you need. What you should instead
do is pick up one of the popular web frameworks like Django, Flask,
Bottle, etc, and use that. Pick a framework (personally, I use Flask,
but you can use any of them), and work through its tutorial. Then,
depending on how fancy you want your site to be, you'll need anywhere
from basic to advanced knowledge of the web's client-side technologies
- HTML, CSS, JavaScript, and possibly some libraries like Bootstrap,
jQuery, etc. Again, pick up any that you want to use, and work through
their tutorials.

This is a massively open-ended goal. You can make this as big or small
as you want.

ChrisA


From marko at pacujo.net  Mon Nov 23 07:23:09 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 23 Nov 2015 14:23:09 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <n2sfbh$l8f$1@dont-email.me>
 <5652535a$0$1596$c3e8da3$5496439d@news.astraweb.com>
 <mailman.55.1448237105.2291.python-list@python.org>
 <n2tn01$ko3$1@dont-email.me>
Message-ID: <87oaekq502.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> I think I'm done here.

Bart, this is the internet. Just skip the articles you don't find
uplifting.


Marko


From steve at pearwood.info  Mon Nov 23 08:08:03 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 24 Nov 2015 00:08:03 +1100
Subject: pip does not work anymore
References: <87vb8trw9l.fsf@Equus.decebal.nl>
Message-ID: <56530fb4$0$1589$c3e8da3$5496439d@news.astraweb.com>

On Mon, 23 Nov 2015 06:48 pm, Cecil Westerhof wrote:

> When I try to install something with pip2 I get:
>     Traceback (most recent call last):
[...]
>         from urllib2 import (Request, urlopen, URLError, HTTPError,
>     ImportError: cannot import name HTTPSHandler

Before blaming SUSE for breaking this, please run this at the interactive
interpreter:

import urllib2
print urllib2.__file__


Have you perhaps accidentally shadowed the std lib module?



-- 
Steven



From gengyangcai at gmail.com  Mon Nov 23 08:26:26 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Mon, 23 Nov 2015 05:26:26 -0800 (PST)
Subject: Creating a Dynamic Website Using Python
In-Reply-To: <mailman.65.1448281265.2291.python-list@python.org>
References: <7710a5aa-ef92-40a9-9b00-59ed1dc80103@googlegroups.com>
 <mailman.65.1448281265.2291.python-list@python.org>
Message-ID: <b59f3646-c301-4d39-b1cc-5d1daeb12ec6@googlegroups.com>

Ok, I will look through the Flask tutorials then ...


On Monday, November 23, 2015 at 8:21:28 PM UTC+8, Chris Angelico wrote:
> On Mon, Nov 23, 2015 at 8:55 PM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> > So I have gone through the CodeAcademy Python modules and decided to jump straight into a project.
> >
> > I want to create a dynamic web-based site like this --- https://www.wedpics.com using Python
> >
> > How / where do I start ?
> 
> While it's *possible* to create a web site using just a base Python
> install, it's a lot more work than you need. What you should instead
> do is pick up one of the popular web frameworks like Django, Flask,
> Bottle, etc, and use that. Pick a framework (personally, I use Flask,
> but you can use any of them), and work through its tutorial. Then,
> depending on how fancy you want your site to be, you'll need anywhere
> from basic to advanced knowledge of the web's client-side technologies
> - HTML, CSS, JavaScript, and possibly some libraries like Bootstrap,
> jQuery, etc. Again, pick up any that you want to use, and work through
> their tutorials.
> 
> This is a massively open-ended goal. You can make this as big or small
> as you want.
> 
> ChrisA



From sridhargunasekaran at gmail.com  Mon Nov 23 08:55:59 2015
From: sridhargunasekaran at gmail.com (sridhar gunasekaran)
Date: Mon, 23 Nov 2015 19:25:59 +0530
Subject: No subject
Message-ID: <56531af0.0f13620a.cf2d9.6179@mx.google.com>

Hai I have installed python 3.5 in my pc I could not see any application icon or application shortcut on my pc


Sent from Mail for Windows 10


From steve at pearwood.info  Mon Nov 23 08:58:55 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 24 Nov 2015 00:58:55 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <dbf29qFoem0U1@mid.individual.net>
 <5652c4ac$0$1621$c3e8da3$5496439d@news.astraweb.com>
 <n2uqau$mme$1@dont-email.me>
Message-ID: <56531ba1$0$1597$c3e8da3$5496439d@news.astraweb.com>

On Mon, 23 Nov 2015 09:40 pm, BartC wrote:

> On 23/11/2015 07:47, Steven D'Aprano wrote:
> 
>> I think it would be cleaner and better if Python had dedicated syntax for
>> declaring static local variables:
> 
> Interesting. So why is it that when /I/ said:
> 
>  > On Mon, 23 Nov 2015 12:21 am, BartC wrote:
>  >
>  >> But if it's used for static storage, then why not just use static
>  >> storage?
> 
> You replied with the insulting:
> 
>  > /head-desk
> 
> ?
> 
> Maybe it's my turn to bang my head on the desk.

Let me steal^W borrow an idea from Galileo, and present the explanation in
the form of a dialogue between two philosophers of computer science,
Salviati and Simplicio, and a third, intelligent layman, Sagredo.

https://en.wikipedia.org/wiki/Dialogue_Concerning_the_Two_Chief_World_Systems


Salviati: Function defaults can also be used for static storage.

Simplicio: If you want static storage, why not use static storage?

Salviati: Function defaults in Python *are* static storage.

    Although they not the only way to get static storage, as closures can
also be used for that purpose, they are surely the simplest way to get
static storage in Python.

Sagredo: Simplest though it might be, surely a reasonable person would
consider that using function parameters for static storage is abuse of the
feature and a global variable would be better?

Salviati: Global variables have serious disadvantages. I will agree that
using function parameters for static storage is something of a code smell,
but good enough for rough and ready code. Nevertheless, it would be good if
Python had dedicated syntax for static storage.

Simplicio: Ah-ha! Gotcha!

Salviati: No, perhaps you missed that I was referring to a hypothetical
future addition to Python, not a current feature. But even if it did exist
today, your statement misses the point that by using function defaults I
*am* using static storage. In effect, you are telling me that rather than
using static storage I should instead use static storage.




-- 
Steven



From me at sntsh.com  Mon Nov 23 09:16:31 2015
From: me at sntsh.com (Santosh Kumar)
Date: Mon, 23 Nov 2015 19:46:31 +0530
Subject: How to remember last position and size (geometry) of PyQt
 application?
In-Reply-To: <CAE7MaQZj=smhVjxBzv2osAYEL8wVGbiwB3LJ2sPDx2trNWPUaA@mail.gmail.com>
References: <CAE7MaQZj=smhVjxBzv2osAYEL8wVGbiwB3LJ2sPDx2trNWPUaA@mail.gmail.com>
Message-ID: <CAE7MaQYg8Qidaj+CTu=NR_ez9Go6Jw_umjkUYJXtt=Mb==Y8QA@mail.gmail.com>

This question was reasked and answered on StackOverflow:
http://stackoverflow.com/q/33869721/939986


From ian.g.kelly at gmail.com  Mon Nov 23 11:40:50 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 23 Nov 2015 09:40:50 -0700
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmrWnMPhEY8wmV0dzdMjfDJPAj0oArpt1d+h0B5uw3wzsA@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <CAPTjJmrWnMPhEY8wmV0dzdMjfDJPAj0oArpt1d+h0B5uw3wzsA@mail.gmail.com>
Message-ID: <CALwzidkW=0G78piPvWCGh=GfDAj_KYPui07354-d1demmMZR9w@mail.gmail.com>

On Mon, Nov 23, 2015 at 1:23 AM, Chris Angelico <rosuav at gmail.com> wrote:
> def latearg(f):
>     tot_args = f.__code__.co_argcount
>     min_args = tot_args - len(f.__defaults__)
>     defs = f.__defaults__
>     # With compiler help, we could get the original text as well as something
>     # executable that works in the correct scope. Without compiler help, we
>     # either use a lambda function, or an exec/eval monstrosity that can't use
>     # the scope of its notional definition (since its *actual* definition will
>     # be inside this decorator). Instead, just show a fixed bit of text.

You should be able to get the correct globals from f.__globals__.

For locals, the decorator might capture the locals of the previous
stack frame at the moment the decorator was called, but that's
potentially a pretty heavy thing to be retaining for this purpose; the
definition of a @latearg function would indefinitely keep a reference
to every single object that was bound to a variable in that scope, not
just the things it needs. For better specificity you could parse the
expression and then just grab the names that it uses. Even so, this
would still act somewhat like early binding in that it would reference
the local variables at the time of definition rather than evaluation.

Nonlocals? Just forget about it.

> This does implement late binding, but:
> 1) The adornment is the rather verbose "lambda:", where I'd much
> rather have something shorter
> 2) Since there's no way to recognize "the ones that were adorned", the
> decorator checks for "anything callable"

A parameter annotation could be used in conjunction with the decorator.

@latearg
def x(y: latearg = lambda: []):
    ...

But that's even more verbose. In the simple case where all the
defaults should be late, one could have something like:

@latearg('*')
def x(y=lambda: []):
    ...

The argument could be generalized to pass a set of parameter names as
an alternative to the annotation.

> 3) Keyword args aren't handled - they're passed through as-is (and
> keyword-only arg defaults aren't rendered)

I would expect that Python 3 Signature objects would make this a lot
simpler to handle.


From framstag at rus.uni-stuttgart.de  Mon Nov 23 12:01:55 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Mon, 23 Nov 2015 17:01:55 +0000 (UTC)
Subject: non-blocking getkey?
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
Message-ID: <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>

eryksun <eryksun at gmail.com> wrote:
> On Thu, Nov 19, 2015 at 10:31 AM, Michael Torrie <torriem at gmail.com> wrote:
> > One windows it might be possible to use the win32 api to enumerate the
> > windows, find your console window and switch to it.
> 
> You can call GetConsoleWindow [1] and then SetForegroundWindow [2].
(...)

Sorry, for the late feedback: 
great, this works! Thanks!
 

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From c.buhtz at posteo.jp  Mon Nov 23 12:04:01 2015
From: c.buhtz at posteo.jp (c.buhtz at posteo.jp)
Date: Mon, 23 Nov 2015 18:04:01 +0100
Subject: [argparse] optional parameter without --switch
Message-ID: <3p4FFS0cRdz5vNy@dovecot03.posteo.de>

I want to call (on bash) a Python script in this two ways without any
error.

    ./arg.py
    ./arg.py TEST

It means that the parameter (here with the value `TEST`) should be
optional. With argparse I only know a way to create optional paramters
when they have a switch (like `--name`).

Is there a way to fix that?

    #!/usr/bin/env python3    
    import sys
    import argparse

    parser = argparse.ArgumentParser(description=__file__)
    
    # must have
    #parser.add_argument('name', metavar='NAME', type=str)
    
    # optional BUT with a switch I don't want
    #parser.add_argument('--name', metavar='NAME', type=str)
    
    # store all arguments in objects/variables of the local namespace
    locals().update(vars(parser.parse_args()))
    
    print(name)
    
    sys.exit()
-- 
GnuPGP-Key ID 0751A8EC


From rosuav at gmail.com  Mon Nov 23 12:05:13 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 24 Nov 2015 04:05:13 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CALwzidkW=0G78piPvWCGh=GfDAj_KYPui07354-d1demmMZR9w@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <CAPTjJmrWnMPhEY8wmV0dzdMjfDJPAj0oArpt1d+h0B5uw3wzsA@mail.gmail.com>
 <CALwzidkW=0G78piPvWCGh=GfDAj_KYPui07354-d1demmMZR9w@mail.gmail.com>
Message-ID: <CAPTjJmq6w4Ob2YifQF6Ok9vcbmpwDMUOTD7sY0n3FZV_+LdbZg@mail.gmail.com>

On Tue, Nov 24, 2015 at 3:40 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Mon, Nov 23, 2015 at 1:23 AM, Chris Angelico <rosuav at gmail.com> wrote:
>> def latearg(f):
>>     tot_args = f.__code__.co_argcount
>>     min_args = tot_args - len(f.__defaults__)
>>     defs = f.__defaults__
>>     # With compiler help, we could get the original text as well as something
>>     # executable that works in the correct scope. Without compiler help, we
>>     # either use a lambda function, or an exec/eval monstrosity that can't use
>>     # the scope of its notional definition (since its *actual* definition will
>>     # be inside this decorator). Instead, just show a fixed bit of text.
>
> You should be able to get the correct globals from f.__globals__.
>
> For locals, the decorator might capture the locals of the previous
> stack frame at the moment the decorator was called, but that's
> potentially a pretty heavy thing to be retaining for this purpose; the
> definition of a @latearg function would indefinitely keep a reference
> to every single object that was bound to a variable in that scope, not
> just the things it needs. For better specificity you could parse the
> expression and then just grab the names that it uses. Even so, this
> would still act somewhat like early binding in that it would reference
> the local variables at the time of definition rather than evaluation.
>
> Nonlocals? Just forget about it.

And since nonlocals are fundamentally unsolvable, I took the simpler
option and just used an actual lambda function.

>> This does implement late binding, but:
>> 1) The adornment is the rather verbose "lambda:", where I'd much
>> rather have something shorter
>> 2) Since there's no way to recognize "the ones that were adorned", the
>> decorator checks for "anything callable"
>
> A parameter annotation could be used in conjunction with the decorator.
>
> @latearg
> def x(y: latearg = lambda: []):
>     ...
>
> But that's even more verbose. In the simple case where all the
> defaults should be late, one could have something like:
>
> @latearg('*')
> def x(y=lambda: []):
>     ...
>
> The argument could be generalized to pass a set of parameter names as
> an alternative to the annotation.

Yeah, that might help. With real compiler support, both of these could
be solved:

def x(y=>[]):
    ...

The displayed default could be "=>[]", exactly the way it's seen in
the source, and the run-time would know exactly which args were
flagged this way. Plus, it could potentially use a single closure to
evaluate all the arguments.

>> 3) Keyword args aren't handled - they're passed through as-is (and
>> keyword-only arg defaults aren't rendered)
>
> I would expect that Python 3 Signature objects would make this a lot
> simpler to handle.

Maybe. It's still going to be pretty complicated. I could easily
handle keyword-only arguments, but recognizing that something in **kw
is replacing something in *a is a bit harder. Expansion invited.

This is reminiscent of the manual "yield from" implementation in PEP
380. It looks simple enough, until you start writing in all the corner
cases.

ChrisA


From israel at ravnalaska.net  Mon Nov 23 12:54:38 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 08:54:38 -0900
Subject: Bi-directional sub-process communication
Message-ID: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>

I have a multi-threaded python app (CherryPy WebApp to be exact) that launches a child process that it then needs to communicate with bi-driectionally. To implement this, I have used a pair of Queues: a child_queue which I use for master->child communication, and a master_queue which is used for child->master communication.

The way I have the system set up, the child queue runs a loop in a tread that waits for messages on child_queue, and when received responds appropriately depending on the message received, which sometimes involves posting a message to master_queue.

On the master side, when it needs to communicate with the child process, it posts a message to child_queue, and if the request requires a response it will then immediately start waiting for a message on master_queue, typically with a timeout.

While this process works well in testing, I do have one concern (maybe unfounded) and a real-world issue

Concern: Since the master process is multi-threaded, it seems likely enough that multiple threads on the master side would make requests at the same time. I understand that the Queue class has locks that make this fine (one thread will complete posting the message before the next is allowed to start), and since the child process only has a single thread processing messages from the queue, it should process them in order and post the responses (if any) to the master_queue in order. But now I have multiple master processes all trying to read master_queue at the same time. Again, the locks will take care of this and prevent any overlapping reads, but am I guaranteed that the threads will obtain the lock and therefore read the responses in the right order? Or is there a possibility that, say, thread three will get the response that should have been for thread one? Is this something I need to take into consideration, and if so, how?

Real-world problem: While as I said this system worked well in testing, Now that I have gotten it out into production I've occasionally run into a problem where the master thread waiting for a response on master_queue times out while waiting. This causes a (potentially) two-fold problem, in that first off the master process doesn't get the information it had requested, and secondly that I *could* end up with an "orphaned" message on the queue that could cause problems the next time I try to read something from it.

I currently have the timeout set to 3 seconds. I can, of course, increase that, but that could lead to a bad user experience - and might not even help the situation if something else is going on. The actual exchange is quite simple:

On the master side, I have this code:

config.socket_queue.put('GET_PORT')
try:
    port = config.master_queue.get(timeout=3)  #wait up to three seconds for a response
except Empty:
     port = 5000  # default. Can't hurt to try.

Which, as you might have been able to guess, tries to ask the child process (an instance of a tornado server, btw) what port it is listening on. The child process then, on getting this message from the queue, runs the following code:

elif item == 'GET_PORT':
      port = utils.config.getint('global', 'tornado.port')
      master_queue.put(port)

So nothing that should take any significant time. Of course, since this is a single thread handling any number of requests, it is possible that the thread is tied up responding to a different request (or that the GIL is preventing the thread from running at all, since another thread might be commandeering the processor), but I find it hard to believe that it could be tied up for more than three seconds.

So is there a better way to do sub-process bi-directional communication that would avoid these issues? Or do I just need to increase the timeout (or remove it altogether, at the risk of potentially causing the thread to hang if no message is posted)? And is my concern justified, or just paranoid? Thanks for any information that can be provided!

-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------






From Cecil at decebal.nl  Mon Nov 23 13:23:57 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Mon, 23 Nov 2015 19:23:57 +0100
Subject: pip does not work anymore
References: <87vb8trw9l.fsf@Equus.decebal.nl>
 <56530fb4$0$1589$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87mvu4r2v6.fsf@Equus.decebal.nl>

On Monday 23 Nov 2015 14:08 CET, Steven D'Aprano wrote:

> On Mon, 23 Nov 2015 06:48 pm, Cecil Westerhof wrote:
>
>> When I try to install something with pip2 I get:
>> Traceback (most recent call last):
> [...]
>> from urllib2 import (Request, urlopen, URLError, HTTPError,
>> ImportError: cannot import name HTTPSHandler
>
> Before blaming SUSE for breaking this, please run this at the
> interactive interpreter:
>
> import urllib2
> print urllib2.__file__
>
>
> Have you perhaps accidentally shadowed the std lib module?

It worked without fail before the update, but you never know:
    Python 2.7.9 (default, Dec 13 2014, 18:02:08) [GCC] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import urllib2
    >>> print urllib2.__file__
    /usr/lib64/python2.7/urllib2.pyc

So I did not shadow I would think.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From israel at ravnalaska.net  Mon Nov 23 13:29:28 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 09:29:28 -0900
Subject: Designing DBI compliant SQL parameters for module
Message-ID: <92FBE0C8-2853-4F3F-9F85-1144EE4D4EC7@ravnalaska.net>

My company uses a database (4th dimension) for which there was no python DBI compliant driver available (I had to use ODBC, which I felt was cludgy). However, I did discover that the company had a C driver available, so I went ahead and used CFFI to wrap this driver into a DBI compliant python module (https://pypi.python.org/pypi/p4d). This works well (still need to make it python 3.x compatible), but since the underlying C library uses "qmark" style parameter markers, that's all I implemented in my module.

I would like to expand the module to be able to use the more-common (or at least easier for me) "format" and "pyformat" parameter markers, as indicated in the footnote to PEP-249 (https://www.python.org/dev/peps/pep-0249/#id2 at least for the pyformat markers). Now I am fairly confidant that I can write code to convert such placeholders into the qmark style markers that the underlying library provides, but before I go and re-invent the wheel, is there already code that does this which I can simply use, or modify?
-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------






From ian.g.kelly at gmail.com  Mon Nov 23 14:55:49 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 23 Nov 2015 12:55:49 -0700
Subject: Bi-directional sub-process communication
In-Reply-To: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>
References: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>
Message-ID: <CALwzidkz6LdFeXsRZW1sAYxXvJGRX5KA5XsM4T0dEOb34C9HDQ@mail.gmail.com>

On Mon, Nov 23, 2015 at 10:54 AM, Israel Brewster <israel at ravnalaska.net> wrote:
> Concern: Since the master process is multi-threaded, it seems likely enough that multiple threads on the master side would make requests at the same time. I understand that the Queue class has locks that make this fine (one thread will complete posting the message before the next is allowed to start), and since the child process only has a single thread processing messages from the queue, it should process them in order and post the responses (if any) to the master_queue in order. But now I have multiple master processes all trying to read master_queue at the same time. Again, the locks will take care of this and prevent any overlapping reads, but am I guaranteed that the threads will obtain the lock and therefore read the responses in the right order? Or is there a possibility that, say, thread three will get the response that should have been for thread one? Is this something I need to take into consideration, and if so, how?

Yes, if multiple master threads are waiting on the queue, it's
possible that a master thread could get a response that was not
intended for it. As far as I know there's no guarantee that the
waiting threads will be woken up in the order that they called get(),
but even if there are, consider this case:

Thread A enqueues a request.
Thread B preempts A and enqueues a request.
Thread B calls get on the response queue.
Thread A calls get on the response queue.
The response from A's request arrives and is given to B.

Instead of having the master threads pull objects off the response
queue directly, you might create another thread whose sole purpose is
to handle the response queue. That could look like this:


request_condition = threading.Condition()
response_global = None

def master_thread():
    global response_global
    with request_condition:
        request_queue.put(request)
        request_condition.wait()
        # Note: the Condition should remain acquired until
response_global is reset.
        response = response_global
        response_global = None
    if wrong_response(response):
        raise RuntimeError("got a response for the wrong request")
    handle_response(response)

def response_thread():
    global response_global
    while True:
        response = response_queue.get()
        with request_condition:
            response_global = response
            request_condition.notify()


As another option you could use a multiprocessing.Manager to
coordinate passing the response back more directly, but starting a
third process seems like overkill for this.


From ian.g.kelly at gmail.com  Mon Nov 23 15:51:51 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 23 Nov 2015 13:51:51 -0700
Subject: Bi-directional sub-process communication
In-Reply-To: <CALwzidkz6LdFeXsRZW1sAYxXvJGRX5KA5XsM4T0dEOb34C9HDQ@mail.gmail.com>
References: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>
 <CALwzidkz6LdFeXsRZW1sAYxXvJGRX5KA5XsM4T0dEOb34C9HDQ@mail.gmail.com>
Message-ID: <CALwzidkFoar6mtiH8xhHPta=HbZdKpaiMPxjH2HegXHAS1jLAw@mail.gmail.com>

On Mon, Nov 23, 2015 at 12:55 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Mon, Nov 23, 2015 at 10:54 AM, Israel Brewster <israel at ravnalaska.net> wrote:
>> Concern: Since the master process is multi-threaded, it seems likely enough that multiple threads on the master side would make requests at the same time. I understand that the Queue class has locks that make this fine (one thread will complete posting the message before the next is allowed to start), and since the child process only has a single thread processing messages from the queue, it should process them in order and post the responses (if any) to the master_queue in order. But now I have multiple master processes all trying to read master_queue at the same time. Again, the locks will take care of this and prevent any overlapping reads, but am I guaranteed that the threads will obtain the lock and therefore read the responses in the right order? Or is there a possibility that, say, thread three will get the response that should have been for thread one? Is this something I need to take into consideration, and if so, how?
>
> Yes, if multiple master threads are waiting on the queue, it's
> possible that a master thread could get a response that was not
> intended for it. As far as I know there's no guarantee that the
> waiting threads will be woken up in the order that they called get(),
> but even if there are, consider this case:
>
> Thread A enqueues a request.
> Thread B preempts A and enqueues a request.
> Thread B calls get on the response queue.
> Thread A calls get on the response queue.
> The response from A's request arrives and is given to B.
>
> Instead of having the master threads pull objects off the response
> queue directly, you might create another thread whose sole purpose is
> to handle the response queue. That could look like this:
>
>
> request_condition = threading.Condition()
> response_global = None
>
> def master_thread():
>     global response_global
>     with request_condition:
>         request_queue.put(request)
>         request_condition.wait()
>         # Note: the Condition should remain acquired until
> response_global is reset.
>         response = response_global
>         response_global = None
>     if wrong_response(response):
>         raise RuntimeError("got a response for the wrong request")
>     handle_response(response)
>
> def response_thread():
>     global response_global
>     while True:
>         response = response_queue.get()
>         with request_condition:
>             response_global = response
>             request_condition.notify()

Actually I realized that this fails because if two threads get
notified at about the same time, they could reacquire the Condition in
the wrong order and so get the wrong responses.

Concurrency, ugh.

It's probably better just to have a Condition/Event per thread and
have the response thread identify the correct one to notify, rather
than just notify a single shared Condition and hope the threads wake
up in the right order.


From vostrushka at gmail.com  Mon Nov 23 15:58:31 2015
From: vostrushka at gmail.com (Crane Ugly)
Date: Mon, 23 Nov 2015 12:58:31 -0800 (PST)
Subject: Problem to read from array
In-Reply-To: <mailman.40.1448121134.2291.python-list@python.org>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <n2q2bd$rf0$1@dont-email.me>
 <mailman.40.1448121134.2291.python-list@python.org>
Message-ID: <81290337-638d-4e50-a85f-054e0a220357@googlegroups.com>

Thank you all.
Here is the last piece of code that caused me so much troubles but now working the way I wanted it: 

	fRawData = []
	with open(fStagingFile2) as fStagingFile2FH:
		fRawData = [line.strip() for line in fStagingFile2FH.readlines()]         # #### This is to read each element from the file and chop off the end of line character
	
	fNumberOfColumns = 7
	fNumberOfRows = len(fRawData)/fNumberOfColumns

	fRowID = 0
	fParameters = []
	for fRowID in range(0, len(fRawData), fNumberOfColumns):
		fParameters.append(fRawData[fRowID:fRowID+fNumberOfColumns])     # #### This is to convert 1D array to 2D

    # #### ... and down below section is an example of how to read each element of the list
    # #### and how to update it if I need so. That was also a problem before.
	fRowID = 0
	fColumnID = 0
	for fRowID in range(fNumberOfRows):
		for fColumnID in range(fNumberOfColumns):
			if fColumnID == 0:
				fParameters[fRowID][fColumnID] = "XXXX"
			Message2Log("fParameters[" + str(fRowID) + "][" + str(fColumnID) + "] = " + str(fParameters[fRowID][fColumnID]))

CU

On Saturday, November 21, 2015 at 4:52:35 PM UTC+1, Nathan Hilterbrand wrote:
> On 11/21/2015 10:26 AM, BartC wrote:
> > On 21/11/2015 10:41, vostrushka at gmail.com wrote:
> >> Hi,
> >> I have a file with one parameter per line:
> >> a1
> >> b1
> >> c1
> >> a2
> >> b2
> >> c2
> >> a3
> >> b3
> >> c3
> >> ...
> >> The parameters are lines of characters (not numbers)
> >>
> >> I need to load it to 2D array for further manipulations.
> >> So far I managed to upload this file into 1D array:
> >>
> >> ParametersRaw = []
> >> with open(file1) as fh:
> >>      ParametersRaw = fh.readlines()
> >> fh.close()
> >
> > I tried this code based on yours:
> >
> > with open("input") as fh:
> >     lines=fh.readlines()
> >
> > rows = len(lines)//3
> >
> > params=[]
> > index=0
> >
> > for row in range(rows):
> >     params.append([lines[index],lines[index+1],lines[index+2]])
> >     index += 3
> >
> > for row in range(rows):
> >     print (row,":",params[row])
> >
> > For the exact input you gave, it produced this output:
> >
> > 0 : ['a1\n', 'b1\n', 'c1\n']
> > 1 : ['a2\n', 'b2\n', 'c2\n']
> > 2 : ['a3\n', 'b3\n', 'c3\n']
> >
> > Probably you'd want to get rid of those \n characters. (I don't know 
> > how off-hand as I'm not often write in Python.)
> >
> > The last bit could also be written:
> >
> > for param in params:
> >     print (params)
> >
> > but I needed the row index.
> >
> To get rid of the '\n' (lineend) characters:
> 
> with open(file1) as fh:
>      ParametersRaw = [line.strip() for line in fh.readlines()]
> 
> or, more succinctly..
> 
>   with open(file1) as fh:
>       ParametersRaw = [line.strip() for line in fh]
> 
> Comprehensions are your friend.
> 
> Nathan


From israel at ravnalaska.net  Mon Nov 23 16:22:33 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 12:22:33 -0900
Subject: Bi-directional sub-process communication
In-Reply-To: <CALwzidkFoar6mtiH8xhHPta=HbZdKpaiMPxjH2HegXHAS1jLAw@mail.gmail.com>
References: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>
 <CALwzidkz6LdFeXsRZW1sAYxXvJGRX5KA5XsM4T0dEOb34C9HDQ@mail.gmail.com>
 <CALwzidkFoar6mtiH8xhHPta=HbZdKpaiMPxjH2HegXHAS1jLAw@mail.gmail.com>
Message-ID: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>

On Nov 23, 2015, at 11:51 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> 
> On Mon, Nov 23, 2015 at 12:55 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> On Mon, Nov 23, 2015 at 10:54 AM, Israel Brewster <israel at ravnalaska.net> wrote:
>>> Concern: Since the master process is multi-threaded, it seems likely enough that multiple threads on the master side would make requests at the same time. I understand that the Queue class has locks that make this fine (one thread will complete posting the message before the next is allowed to start), and since the child process only has a single thread processing messages from the queue, it should process them in order and post the responses (if any) to the master_queue in order. But now I have multiple master processes all trying to read master_queue at the same time. Again, the locks will take care of this and prevent any overlapping reads, but am I guaranteed that the threads will obtain the lock and therefore read the responses in the right order? Or is there a possibility that, say, thread three will get the response that should have been for thread one? Is this something I need to take into consideration, and if so, how?
>> 
>> Yes, if multiple master threads are waiting on the queue, it's
>> possible that a master thread could get a response that was not
>> intended for it. As far as I know there's no guarantee that the
>> waiting threads will be woken up in the order that they called get(),
>> but even if there are, consider this case:
>> 
>> Thread A enqueues a request.
>> Thread B preempts A and enqueues a request.
>> Thread B calls get on the response queue.
>> Thread A calls get on the response queue.
>> The response from A's request arrives and is given to B.
>> 
>> Instead of having the master threads pull objects off the response
>> queue directly, you might create another thread whose sole purpose is
>> to handle the response queue. That could look like this:
>> 
>> 
>> request_condition = threading.Condition()
>> response_global = None
>> 
>> def master_thread():
>>    global response_global
>>    with request_condition:
>>        request_queue.put(request)
>>        request_condition.wait()
>>        # Note: the Condition should remain acquired until
>> response_global is reset.
>>        response = response_global
>>        response_global = None
>>    if wrong_response(response):
>>        raise RuntimeError("got a response for the wrong request")
>>    handle_response(response)
>> 
>> def response_thread():
>>    global response_global
>>    while True:
>>        response = response_queue.get()
>>        with request_condition:
>>            response_global = response
>>            request_condition.notify()
> 
> Actually I realized that this fails because if two threads get
> notified at about the same time, they could reacquire the Condition in
> the wrong order and so get the wrong responses.
> 
> Concurrency, ugh.
> 
> It's probably better just to have a Condition/Event per thread and
> have the response thread identify the correct one to notify, rather
> than just notify a single shared Condition and hope the threads wake
> up in the right order.

Tell me about it :-) I've actually never worked with conditions or notifications (actually even this bi-drectional type of communication is new to me), so I'll have to look into that and figure it out. Thanks for the information!

> -- 
> https://mail.python.org/mailman/listinfo/python-list



From cs at zip.com.au  Mon Nov 23 16:45:16 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Tue, 24 Nov 2015 08:45:16 +1100
Subject: Bi-directional sub-process communication
In-Reply-To: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>
References: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>
Message-ID: <20151123214516.GA56871@cskk.homeip.net>

On 23Nov2015 12:22, Israel Brewster <israel at ravnalaska.net> wrote:
>On Nov 23, 2015, at 11:51 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> Concurrency, ugh.

I'm a big concurrency fan myself.

>> It's probably better just to have a Condition/Event per thread and
>> have the response thread identify the correct one to notify, rather
>> than just notify a single shared Condition and hope the threads wake
>> up in the right order.
>
>Tell me about it :-) I've actually never worked with conditions or 
>notifications (actually even this bi-drectional type of communication is new 
>to me), so I'll have to look into that and figure it out. Thanks for the 
>information!

I include a tag with every request, and have the responses include the tag; the 
request submission function records the response hander in a mapping by tag and 
the response handing thread looks up the mapping and passes the response to the 
right handler.

Works just fine and avoids all the worrying about ordering etc.

Israel, do you have control over the protocol between you and your subprocess?  
If so, adding tags is easy and effective.

Cheers,
Cameron Simpson <cs at zip.com.au>


From plbrrt7 at hotmail.com  Mon Nov 23 17:09:06 2015
From: plbrrt7 at hotmail.com (Alexandre Barreto)
Date: Mon, 23 Nov 2015 22:09:06 +0000
Subject: No subject
Message-ID: <COL401-EAS181A4CAB08345FAA6B014B0F2070@phx.gbl>

I install python 3.5.0 and run eazy to install and my antiv?rus detect and trogen can you explay cus im new to this language.

From israel at ravnalaska.net  Mon Nov 23 17:18:58 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 13:18:58 -0900
Subject: Bi-directional sub-process communication
In-Reply-To: <20151123214516.GA56871@cskk.homeip.net>
References: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>
 <20151123214516.GA56871@cskk.homeip.net>
Message-ID: <F76E321F-3DE0-4FF7-90B4-5EA8A1017C71@ravnalaska.net>

On Nov 23, 2015, at 12:45 PM, Cameron Simpson <cs at zip.com.au> wrote:
> 
> On 23Nov2015 12:22, Israel Brewster <israel at ravnalaska.net> wrote:
>> On Nov 23, 2015, at 11:51 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>>> Concurrency, ugh.
> 
> I'm a big concurrency fan myself.
> 
>>> It's probably better just to have a Condition/Event per thread and
>>> have the response thread identify the correct one to notify, rather
>>> than just notify a single shared Condition and hope the threads wake
>>> up in the right order.
>> 
>> Tell me about it :-) I've actually never worked with conditions or notifications (actually even this bi-drectional type of communication is new to me), so I'll have to look into that and figure it out. Thanks for the information!
> 
> I include a tag with every request, and have the responses include the tag; the request submission function records the response hander in a mapping by tag and the response handing thread looks up the mapping and passes the response to the right handler.
> 
> Works just fine and avoids all the worrying about ordering etc.
> 
> Israel, do you have control over the protocol between you and your subprocess?  If so, adding tags is easy and effective.

I do, and the basic concept makes sense. The one difficulty I am seeing is getting back to the thread that requested the data.  Let me know if this makes sense or I am thinking about it wrong:

- When a thread requests some data, it sends the request as a dictionary containing a tag (unique to the thread) as well as the request
- When the child processes the request, it encodes the response as a dictionary containing the tag and the response data
- A single, separate thread on the "master" side parses out responses as they come in and puts them into a dictionary keyed by tag
- The requesting threads, after putting the request into the Queue, would then block waiting for data to appear under their key in the dictionary

Of course, that last step could be interesting - implementing the block in such a way as to not tie up the processor, while still getting the data "as soon" as it is available. Unless there is some sort of built-in notification system I could use for that? I.e. the thread would "subscribe" to a notification based on its tag, and then wait for notification. When the master processing thread receives data with said tag, it adds it to the dictionary and "publishes" a notification to that tag. Or perhaps the notification itself could contain the payload? 

Thanks for the information!

> 
> Cheers,
> Cameron Simpson <cs at zip.com.au>



From ckaynor at zindagigames.com  Mon Nov 23 17:43:25 2015
From: ckaynor at zindagigames.com (Chris Kaynor)
Date: Mon, 23 Nov 2015 14:43:25 -0800
Subject: Bi-directional sub-process communication
In-Reply-To: <F76E321F-3DE0-4FF7-90B4-5EA8A1017C71@ravnalaska.net>
References: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>
 <20151123214516.GA56871@cskk.homeip.net>
 <F76E321F-3DE0-4FF7-90B4-5EA8A1017C71@ravnalaska.net>
Message-ID: <CALvWhxtJkWk4_+boowdYSzNex32ckKgaGBa2zhJsrsag7wjkmQ@mail.gmail.com>

On Mon, Nov 23, 2015 at 2:18 PM, Israel Brewster <israel at ravnalaska.net>
wrote:

> Of course, that last step could be interesting - implementing the block in
> such a way as to not tie up the processor, while still getting the data "as
> soon" as it is available. Unless there is some sort of built-in
> notification system I could use for that? I.e. the thread would "subscribe"
> to a notification based on its tag, and then wait for notification. When
> the master processing thread receives data with said tag, it adds it to the
> dictionary and "publishes" a notification to that tag. Or perhaps the
> notification itself could contain the payload?


There are a few ways I could see handling this, without having the threads
spinning and consuming CPU:

   1. Don't worry about having the follow-up code run in the same thread,
   and use a simple callback. This callback could be dispatched to a thread
   via a work queue, however you may not get the same thread as the one that
   made the request. This is probably the most efficient method to use, as the
   threads can continue doing other work while waiting for a reply, rather
   than blocking. It does make it harder to maintain state between the pre-
   and post-request functions, however.
   2. Have a single, global, event variable that wakes all threads waiting
   on a reply, each of which then checks to see if the reply is for it, or
   goes back to sleep. This is good if most of the time, only a few threads
   will be waiting for a reply, and checking if the correct reply came in is
   cheap. This is probably good enough, unless you have a LOT of threads
   (hundreds).
   3. Have an event per thread. This will use less CPU than the second
   option, however does require more memory and OS resources, and so will not
   be viable for huge numbers of threads, though if you hit the limit, you are
   probably using threads wrong.
   4. Have an event per request. This is only better than #3 if a single
   thread may make multiple requests at once, and can do useful work when any
   of them get a reply back (if they need all, it will make no difference).

Generally, I would use option #1 or #2. Option 2 has the advantage of
making it easy to write the functions that use the functionality, while
option 1 will generally use fewer resources, and allows threads to continue
to be used while waiting for replies. How much of a benefit that is depends
on exactly what you are doing.

Option #4 would probably be better implemented using option #1 in all cases
to avoid problems with running out of OS memory - threading features
generally require more limited OS resources than memory. Option #3 will
also often run into the same issues as option #4 in the cases it will
provide any benefit over option #2.

Chris


From israel at ravnalaska.net  Mon Nov 23 18:14:11 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 14:14:11 -0900
Subject: Bi-directional sub-process communication
In-Reply-To: <CALvWhxtJkWk4_+boowdYSzNex32ckKgaGBa2zhJsrsag7wjkmQ@mail.gmail.com>
References: <5A3A00A6-CFD2-42FC-9C87-6F8C6861F775@ravnalaska.net>
 <20151123214516.GA56871@cskk.homeip.net>
 <F76E321F-3DE0-4FF7-90B4-5EA8A1017C71@ravnalaska.net>
 <CALvWhxtJkWk4_+boowdYSzNex32ckKgaGBa2zhJsrsag7wjkmQ@mail.gmail.com>
Message-ID: <84B23819-6214-4BDA-959D-85CD46431212@ravnalaska.net>

On Nov 23, 2015, at 1:43 PM, Chris Kaynor <ckaynor at zindagigames.com> wrote:
> 
> On Mon, Nov 23, 2015 at 2:18 PM, Israel Brewster <israel at ravnalaska.net>
> wrote:
> 
>> Of course, that last step could be interesting - implementing the block in
>> such a way as to not tie up the processor, while still getting the data "as
>> soon" as it is available. Unless there is some sort of built-in
>> notification system I could use for that? I.e. the thread would "subscribe"
>> to a notification based on its tag, and then wait for notification. When
>> the master processing thread receives data with said tag, it adds it to the
>> dictionary and "publishes" a notification to that tag. Or perhaps the
>> notification itself could contain the payload?
> 
> 
> There are a few ways I could see handling this, without having the threads
> spinning and consuming CPU:
> 
>   1. Don't worry about having the follow-up code run in the same thread,
>   and use a simple callback. This callback could be dispatched to a thread
>   via a work queue, however you may not get the same thread as the one that
>   made the request. This is probably the most efficient method to use, as the
>   threads can continue doing other work while waiting for a reply, rather
>   than blocking. It does make it harder to maintain state between the pre-
>   and post-request functions, however.
>   2. Have a single, global, event variable that wakes all threads waiting
>   on a reply, each of which then checks to see if the reply is for it, or
>   goes back to sleep. This is good if most of the time, only a few threads
>   will be waiting for a reply, and checking if the correct reply came in is
>   cheap. This is probably good enough, unless you have a LOT of threads
>   (hundreds).
>   3. Have an event per thread. This will use less CPU than the second
>   option, however does require more memory and OS resources, and so will not
>   be viable for huge numbers of threads, though if you hit the limit, you are
>   probably using threads wrong.
>   4. Have an event per request. This is only better than #3 if a single
>   thread may make multiple requests at once, and can do useful work when any
>   of them get a reply back (if they need all, it will make no difference).
> 
> Generally, I would use option #1 or #2. Option 2 has the advantage of
> making it easy to write the functions that use the functionality, while
> option 1 will generally use fewer resources, and allows threads to continue
> to be used while waiting for replies. How much of a benefit that is depends
> on exactly what you are doing.

While I would agree with #1 in general, the threads, in this case, are CherryPy threads, so I need to get the data and return it to the client in the same function call, which of course means the thread needs to block until the data is ready - it can't return and let the result be processed "later".

Essentially there are times that the web client needs some information that only the Child process has. So the web client requests the data from the master process, and the master process then turns around and requests the data from the child, but it needs to get the data back before it can return it to the web client. So it has to block waiting for the data.

Thus we come to option #2 (or 3), which sounds good but I have no clue how to implement :-) Maybe something like http://pubsub.sourceforge.net ? I'll dig into that.

> 
> Option #4 would probably be better implemented using option #1 in all cases
> to avoid problems with running out of OS memory - threading features
> generally require more limited OS resources than memory. Option #3 will
> also often run into the same issues as option #4 in the cases it will
> provide any benefit over option #2.
> 
> Chris
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From israel at ravnalaska.net  Mon Nov 23 19:27:39 2015
From: israel at ravnalaska.net (Israel Brewster)
Date: Mon, 23 Nov 2015 15:27:39 -0900
Subject: Bi-directional sub-process communication
In-Reply-To: <v1a75bt3d76ve8946k04g43p6t1v911nq1@4ax.com>
References: <B819AD72-C0F9-4E6C-992A-5E5556979883@ravnalaska.net>
 <v1a75bt3d76ve8946k04g43p6t1v911nq1@4ax.com>
Message-ID: <A6E7B920-F8FA-492D-8367-4D341262280C@ravnalaska.net>

On Nov 23, 2015, at 3:05 PM, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> 
> On Mon, 23 Nov 2015 08:54:38 -0900, Israel Brewster <israel at ravnalaska.net>
> declaimed the following:
> 
>> Concern: Since the master process is multi-threaded, it seems likely enough that multiple threads on the master side would make requests at the same time. I understand that the Queue class has locks that make
> 
> 	Multiple "master" threads, to me, means you do NOT have a "master
> process".

But I do: the CherryPy "application", which has multiple threads - one per request (and perhaps a few more) to be exact. It's these request threads that generate the calls to the child process.

> 
> 	Let there be a Queue for EVERY LISTENER.
> 
> 	Send the Queue as part of the request packet.

No luck: "RuntimeError: Queue objects should only be shared between processes through inheritance"

This IS a master process, with multiple threads, trying to communicate with a child process. That said, with some modifications this sort of approach could still work.

-----------------------------------------------
Israel Brewster
Systems Analyst II
Ravn Alaska
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------


> 
> 	Let the subthread reply to the queue that was provided via the packet
> 
> 	Voila! No intermixing of "master/slave" interaction; each slave only
> replies to the master that sent it a command; each master only receives
> replies from slaves it has commanded. Slaves can still be shared, as they
> are given the information of which master they need to speak with.
> 
> 	
> 
> -- 
> 	Wulfraed                 Dennis Lee Bieber         AF6VN
>    wlfraed at ix.netcom.com    HTTP://wlfraed.home.netcom.com/
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From sohcahtoa82 at gmail.com  Mon Nov 23 19:44:54 2015
From: sohcahtoa82 at gmail.com (sohcahtoa82 at gmail.com)
Date: Mon, 23 Nov 2015 16:44:54 -0800 (PST)
Subject: Problem to read from array
In-Reply-To: <81290337-638d-4e50-a85f-054e0a220357@googlegroups.com>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <n2q2bd$rf0$1@dont-email.me>
 <mailman.40.1448121134.2291.python-list@python.org>
 <81290337-638d-4e50-a85f-054e0a220357@googlegroups.com>
Message-ID: <9ea86586-0052-491a-8991-0a5f986c34ae@googlegroups.com>

On Monday, November 23, 2015 at 12:58:49 PM UTC-8, Crane Ugly wrote:
> Thank you all.
> Here is the last piece of code that caused me so much troubles but now working the way I wanted it: 
> 
> 	fRawData = []
> 	with open(fStagingFile2) as fStagingFile2FH:
> 		fRawData = [line.strip() for line in fStagingFile2FH.readlines()]         # #### This is to read each element from the file and chop off the end of line character
> 	
> 	fNumberOfColumns = 7
> 	fNumberOfRows = len(fRawData)/fNumberOfColumns
> 
> 	fRowID = 0
> 	fParameters = []
> 	for fRowID in range(0, len(fRawData), fNumberOfColumns):
> 		fParameters.append(fRawData[fRowID:fRowID+fNumberOfColumns])     # #### This is to convert 1D array to 2D
> 
>     # #### ... and down below section is an example of how to read each element of the list
>     # #### and how to update it if I need so. That was also a problem before.
> 	fRowID = 0
> 	fColumnID = 0
> 	for fRowID in range(fNumberOfRows):
> 		for fColumnID in range(fNumberOfColumns):
> 			if fColumnID == 0:
> 				fParameters[fRowID][fColumnID] = "XXXX"
> 			Message2Log("fParameters[" + str(fRowID) + "][" + str(fColumnID) + "] = " + str(fParameters[fRowID][fColumnID]))
> 
> CU
> 
> On Saturday, November 21, 2015 at 4:52:35 PM UTC+1, Nathan Hilterbrand wrote:
> > On 11/21/2015 10:26 AM, BartC wrote:
> > > On 21/11/2015 10:41, vostrushka at gmail.com wrote:
> > >> Hi,
> > >> I have a file with one parameter per line:
> > >> a1
> > >> b1
> > >> c1
> > >> a2
> > >> b2
> > >> c2
> > >> a3
> > >> b3
> > >> c3
> > >> ...
> > >> The parameters are lines of characters (not numbers)
> > >>
> > >> I need to load it to 2D array for further manipulations.
> > >> So far I managed to upload this file into 1D array:
> > >>
> > >> ParametersRaw = []
> > >> with open(file1) as fh:
> > >>      ParametersRaw = fh.readlines()
> > >> fh.close()
> > >
> > > I tried this code based on yours:
> > >
> > > with open("input") as fh:
> > >     lines=fh.readlines()
> > >
> > > rows = len(lines)//3
> > >
> > > params=[]
> > > index=0
> > >
> > > for row in range(rows):
> > >     params.append([lines[index],lines[index+1],lines[index+2]])
> > >     index += 3
> > >
> > > for row in range(rows):
> > >     print (row,":",params[row])
> > >
> > > For the exact input you gave, it produced this output:
> > >
> > > 0 : ['a1\n', 'b1\n', 'c1\n']
> > > 1 : ['a2\n', 'b2\n', 'c2\n']
> > > 2 : ['a3\n', 'b3\n', 'c3\n']
> > >
> > > Probably you'd want to get rid of those \n characters. (I don't know 
> > > how off-hand as I'm not often write in Python.)
> > >
> > > The last bit could also be written:
> > >
> > > for param in params:
> > >     print (params)
> > >
> > > but I needed the row index.
> > >
> > To get rid of the '\n' (lineend) characters:
> > 
> > with open(file1) as fh:
> >      ParametersRaw = [line.strip() for line in fh.readlines()]
> > 
> > or, more succinctly..
> > 
> >   with open(file1) as fh:
> >       ParametersRaw = [line.strip() for line in fh]
> > 
> > Comprehensions are your friend.
> > 
> > Nathan

What is the significance of prefixing all your variables with "f"?  I've frequently seen people use it to signify the variable is a float, but you're using it for things that aren't floats.


From sohcahtoa82 at gmail.com  Mon Nov 23 19:47:37 2015
From: sohcahtoa82 at gmail.com (sohcahtoa82 at gmail.com)
Date: Mon, 23 Nov 2015 16:47:37 -0800 (PST)
Subject: pip does not work anymore
In-Reply-To: <87vb8trw9l.fsf@Equus.decebal.nl>
References: <87vb8trw9l.fsf@Equus.decebal.nl>
Message-ID: <44438522-c78e-423c-b809-00e0145f8890@googlegroups.com>

On Sunday, November 22, 2015 at 11:59:13 PM UTC-8, Cecil Westerhof wrote:
> When I try to install something with pip2 I get:
>     Traceback (most recent call last):
>       File "/usr/bin/pip2", line 9, in <module>
>         load_entry_point('pip==7.1.2', 'console_scripts', 'pip2')()
>       File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 558, in load_entry_point
>         return get_distribution(dist).load_entry_point(group, name)
>       File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2682, in load_entry_point
>         return ep.load()
>       File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2355, in load
>         return self.resolve()
>       File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2361, in resolve
>         module = __import__(self.module_name, fromlist=['__name__'], level=0)
>       File "/usr/lib/python2.7/site-packages/pip/__init__.py", line 15, in <module>
>         from pip.vcs import git, mercurial, subversion, bazaar  # noqa
>       File "/usr/lib/python2.7/site-packages/pip/vcs/subversion.py", line 9, in <module>
>         from pip.index import Link
>       File "/usr/lib/python2.7/site-packages/pip/index.py", line 30, in <module>
>         from pip.wheel import Wheel, wheel_ext
>       File "/usr/lib/python2.7/site-packages/pip/wheel.py", line 35, in <module>
>         from pip._vendor.distlib.scripts import ScriptMaker
>       File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/scripts.py", line 14, in <module>
>         from .compat import sysconfig, detect_encoding, ZipFile
>       File "/usr/lib/python2.7/site-packages/pip/_vendor/distlib/compat.py", line 31, in <module>
>         from urllib2 import (Request, urlopen, URLError, HTTPError,
>     ImportError: cannot import name HTTPSHandler
> 
> With pip3 I get the same problem.
> 
> It looks like openSUSE has done an upgrade in which it disabled ssl2.
> How can I get pip2/3 working again?
> 
> -- 
> Cecil Westerhof
> Senior Software Engineer
> LinkedIn: http://www.linkedin.com/in/cecilwesterhof

SSL2 *should* be disabled.  It was deprecated nearly 20 years ago, replaced by SSL3, and even THAT has been deprecated.  SSL2 is incredibly insecure.


From baillargeon at visi.com  Mon Nov 23 19:58:13 2015
From: baillargeon at visi.com (Bernard Baillargeon)
Date: Mon, 23 Nov 2015 18:58:13 -0600
Subject: 3.5 64b windows
Message-ID: <039b01d12653$329212f0$97b638d0$@visi.com>

I'd just installed py3.5 most recent (downloaded, installed 11/23/15) and
when starting via the windows start (win 8.1pro) shortcut, I always get this
error.

I'd navigated to the program directory (it installed in
C:\Users\my-ID\AppData\Local\Programs\Python\Python35) and started the
python.exe and that fails as well. (as does pythonw.exe -silently. nothing
even pops!)

 





From george.trojan at noaa.gov  Mon Nov 23 22:25:48 2015
From: george.trojan at noaa.gov (George Trojan)
Date: Tue, 24 Nov 2015 03:25:48 +0000
Subject: tuples in conditional assignment
In-Reply-To: <mailman.36.1447434002.19880.python-list@python.org>
References: <mailman.36.1447434002.19880.python-list@python.org>
Message-ID: <5653D8BC.1040800@noaa.gov>

The following code has bitten me recently:

 >>> t=(0,1)
 >>> x,y=t if t else 8, 9
 >>> print(x, y)
(0, 1) 9

I was assuming that a comma has the highest order of evaluation, that is 
the expression 8, 9 should make a tuple. Why this is not the case?

George




From ben+python at benfinney.id.au  Mon Nov 23 23:49:04 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Tue, 24 Nov 2015 15:49:04 +1100
Subject: tuples in conditional assignment
References: <mailman.36.1447434002.19880.python-list@python.org>
 <5653D8BC.1040800@noaa.gov>
Message-ID: <85r3jgatof.fsf@benfinney.id.au>

George Trojan <george.trojan at noaa.gov> writes:

> The following code has bitten me recently:
>
> >>> t=(0,1)
> >>> x,y=t if t else 8, 9
> >>> print(x, y)
> (0, 1) 9

You can simplify this by taking assignment out of the picture::

    >>> t = (0, 1)
    >>> t if t else 8, 9
    ((0, 1), 9)

So that's an ?expression list? containing a comma. The reference for
expressions tells us::

    An expression list containing at least one comma yields a tuple. The
    length of the tuple is the number of expressions in the list.

    <URL:https://docs.python.org/3/reference/expressions.html#expression-lists>

> I was assuming that a comma has the highest order of evaluation

You were? The operator precedence rules don't even mention comma as an
operator, so why would you assume that?

    <URL:https://docs.python.org/3/reference/expressions.html#operator-precedence>

> that is the expression 8, 9 should make a tuple. Why this is not the
> case?

I'm not sure why it's the case that you assumed that :-)

My practical advice: I don't bother trying to remember the complete
operator precedence rules. My simplified precedence rules are:

* ?+?, ?-? have the same precedence.
* ?*?, ?/?, ?//? have the same precedence.
* For anything else: Use parentheses to explicitly declare the
  precedence I want.

Related: When an expression has enough clauses that it's not *completely
obvious* what's going on, break it up by assigning some sub-parts to
temporary well-chosen descriptive names (not ?t?).

-- 
 \     ?It is far better to grasp the universe as it really is than to |
  `\    persist in delusion, however satisfying and reassuring.? ?Carl |
_o__)                                                            Sagan |
Ben Finney



From cs at zip.com.au  Tue Nov 24 00:25:12 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Tue, 24 Nov 2015 16:25:12 +1100
Subject: Bi-directional sub-process communication
In-Reply-To: <84B23819-6214-4BDA-959D-85CD46431212@ravnalaska.net>
References: <84B23819-6214-4BDA-959D-85CD46431212@ravnalaska.net>
Message-ID: <20151124052512.GA51713@cskk.homeip.net>

On 23Nov2015 14:14, Israel Brewster <israel at ravnalaska.net> wrote:
>On Nov 23, 2015, at 1:43 PM, Chris Kaynor <ckaynor at zindagigames.com> wrote:
>> On Mon, Nov 23, 2015 at 2:18 PM, Israel Brewster <israel at ravnalaska.net>
>> wrote:
>>   3. Have an event per thread. This will use less CPU than the second
>>   option, however does require more memory and OS resources, and so will not
>>   be viable for huge numbers of threads, though if you hit the limit, you are
>>   probably using threads wrong.
[...]
>While I would agree with #1 in general, the threads, in this case, are 
>CherryPy threads, so I need to get the data and return it to the client in the 
>same function call, which of course means the thread needs to block until the 
>data is ready - it can't return and let the result be processed "later".

Then #3. I would have a common function/method for submitting a request to go 
to the subprocess, and have that method return an Event on which to wait. Then 
caller then just waits for the Event and collects the data. Obviously, the 
method does not just return the Event, but an Event and something to receive 
the return data. I've got a class called a Result for this kind of thing; make 
a small class containing an Event and which will have a .result attribute for 
the return information; the submitting method allocates one of these and 
returns it. The response handler gets the instance (by looking it up from the 
tag), sets the .result attribute and fires the Event. Your caller wakes up from 
waiting on the Event and consults the .result attribute.

Completely untested example code:

  class ReturnEvent:
    def __init__(self):
      self.event = Event()

  seq = 0
  re_by_tag = {}

  def submit_request(query):
    global seq, re_by_tag
    tag = seq
    seq += 1
    RE = ReturnEvent()
    re_by_tag[tag] = RE
    send_request(tag, query)
    return RE

  def process_response(tag, response_data):
    RE = re_by_tag.pop(tag)
    RE.result = response_data
    RE.event.set()

  ... CherryPy request handler ...
  RE = submit_request(your_query_info)
  RE.wait()
  response_data = RE.result

Cheers,
Cameron Simpson <cs at zip.com.au>


From cs at zip.com.au  Tue Nov 24 00:29:05 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Tue, 24 Nov 2015 16:29:05 +1100
Subject: Bi-directional sub-process communication
In-Reply-To: <20151124052512.GA51713@cskk.homeip.net>
References: <20151124052512.GA51713@cskk.homeip.net>
Message-ID: <20151124052905.GA41045@cskk.homeip.net>

On 24Nov2015 16:25, Cameron Simpson <cs at zip.com.au> wrote:
>Completely untested example code:
>
> class ReturnEvent:
>   def __init__(self):
>     self.event = Event()

With, of course:

    def wait(self):
      return self.event.wait()

Cheers,
Cameron Simpson <cs at zip.com.au>

Maintainer's Motto: If we can't fix it, it ain't broke.


From rosuav at gmail.com  Tue Nov 24 01:11:20 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 24 Nov 2015 17:11:20 +1100
Subject: 3.5 64b windows
In-Reply-To: <039b01d12653$329212f0$97b638d0$@visi.com>
References: <039b01d12653$329212f0$97b638d0$@visi.com>
Message-ID: <CAPTjJmpJeWCsekVJZNsVQx-D939UqqTGO9A7EiaCbZWu8rj+aw@mail.gmail.com>

On Tue, Nov 24, 2015 at 11:58 AM, Bernard Baillargeon
<baillargeon at visi.com> wrote:
> I'd just installed py3.5 most recent (downloaded, installed 11/23/15) and
> when starting via the windows start (win 8.1pro) shortcut, I always get this
> error.

If you attached something, it didn't arrive. Can you type in the text
of what's happening, please?

ChrisA


From __peter__ at web.de  Tue Nov 24 03:36:38 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 24 Nov 2015 09:36:38 +0100
Subject: [argparse] optional parameter without --switch
References: <3p4FFS0cRdz5vNy@dovecot03.posteo.de>
Message-ID: <n317in$ur6$1@ger.gmane.org>

c.buhtz at posteo.jp wrote:

> I want to call (on bash) a Python script in this two ways without any
> error.
> 
>     ./arg.py
>     ./arg.py TEST
> 
> It means that the parameter (here with the value `TEST`) should be
> optional. With argparse I only know a way to create optional paramters
> when they have a switch (like `--name`).

$ cat tmp.py
#!/usr/bin/env python3
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("name", nargs="?")
print("name =", parser.parse_args().name)
$ ./tmp.py
name = None
$ ./tmp.py 42
name = 42

https://docs.python.org/dev/library/argparse.html#nargs



From vostrushka at gmail.com  Tue Nov 24 03:56:08 2015
From: vostrushka at gmail.com (Crane Ugly)
Date: Tue, 24 Nov 2015 00:56:08 -0800 (PST)
Subject: Problem to read from array
In-Reply-To: <9ea86586-0052-491a-8991-0a5f986c34ae@googlegroups.com>
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <n2q2bd$rf0$1@dont-email.me>
 <mailman.40.1448121134.2291.python-list@python.org>
 <81290337-638d-4e50-a85f-054e0a220357@googlegroups.com>
 <9ea86586-0052-491a-8991-0a5f986c34ae@googlegroups.com>
Message-ID: <357a7214-49bc-48ef-902c-1d48ac80be13@googlegroups.com>

It is nothing more but naming convention. This code was part of the function.
Actually, in the final version I removed that "f" and changed some names of variables to shorter versions.
It is all about your own preferences towards readability of the code and ability of visual capture of the code. I always try to have code that easy to read. At least for myself.

CU

> What is the significance of prefixing all your variables with "f"?  I've frequently seen people use it to > signify the variable is a float, but you're using it for things that aren't floats.


From Tolga.Karabiyikoglu at ankara.edu.tr  Tue Nov 24 03:56:32 2015
From: Tolga.Karabiyikoglu at ankara.edu.tr (Tolga.Karabiyikoglu at ankara.edu.tr)
Date: Tue, 24 Nov 2015 10:56:32 +0200
Subject: Persistent api-ms-win-crt-runtime-i1-1-0.dll start up error
Message-ID: <979fb56bd7b09c3a8944e56bbcc0c481@ankara.edu.tr>

Hi all;

Yesterday just downloaded python-3.5.0-amd64 on windows10 running 
laptop- running flawless.

But my trouble is with my office desktop Windows Vista. Considering the 
processor diference, this time, downloaded the python-3.5.0 (32 bit) 
version.
The question is i am receiving 'api-ms-win-crt-runtime-i1-1-0.dll is 
missing' error on the start up. I think i did update my Visual C++ 
Redistributable gear downloading and running vcredist_x86.exe (32 bit)  
but could not get rid off the error.

Do you have any other recipe for me....


From __peter__ at web.de  Tue Nov 24 04:31:16 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 24 Nov 2015 10:31:16 +0100
Subject: Problem to read from array
References: <2141d7ae-1064-49f3-bf36-ff663fca0ffc@googlegroups.com>
 <n2q2bd$rf0$1@dont-email.me>
 <mailman.40.1448121134.2291.python-list@python.org>
 <81290337-638d-4e50-a85f-054e0a220357@googlegroups.com>
 <9ea86586-0052-491a-8991-0a5f986c34ae@googlegroups.com>
 <357a7214-49bc-48ef-902c-1d48ac80be13@googlegroups.com>
Message-ID: <n31ap4$i61$1@ger.gmane.org>

Crane Ugly wrote:

> I always try to have code that easy to read. 

That's laudable, code is a means of communication.

> At least for myself.

and only for yourself, unfortunately.

Recommended read:

https://www.python.org/dev/peps/pep-0008/




From lac at openend.se  Tue Nov 24 04:54:19 2015
From: lac at openend.se (Laura Creighton)
Date: Tue, 24 Nov 2015 10:54:19 +0100
Subject: Persistent api-ms-win-crt-runtime-i1-1-0.dll start up error
In-Reply-To: <979fb56bd7b09c3a8944e56bbcc0c481@ankara.edu.tr>
References: <979fb56bd7b09c3a8944e56bbcc0c481@ankara.edu.tr>
Message-ID: <201511240954.tAO9sJHh007647@fido.openend.se>

In a message of Tue, 24 Nov 2015 10:56:32 +0200, Tolga.Karabiyikoglu at ankara.edu
.tr writes:
>Hi all;
>
>Yesterday just downloaded python-3.5.0-amd64 on windows10 running 
>laptop- running flawless.
>
>But my trouble is with my office desktop Windows Vista. Considering the 
>processor diference, this time, downloaded the python-3.5.0 (32 bit) 
>version.
>The question is i am receiving 'api-ms-win-crt-runtime-i1-1-0.dll is 
>missing' error on the start up. I think i did update my Visual C++ 
>Redistributable gear downloading and running vcredist_x86.exe (32 bit)  
>but could not get rid off the error.
>
>Do you have any other recipe for me....
>-- 
>https://mail.python.org/mailman/listinfo/python-list

Yes.

You appear to have this problem.

https://bugs.python.org/issue25223

Installing http://www.microsoft.com/en-us/download/details.aspx?id=48234
directly seems to fix it.

Laura


From gengyangcai at gmail.com  Tue Nov 24 05:04:56 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 02:04:56 -0800 (PST)
Subject: Returning a result from 3 items in a list
Message-ID: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>

Here's a dictionary with 3 values : 

results = {
  "gengyang": 14,
  "ensheng": 13,
  "jordan": 12
}

How do I define a function that takes the last of the 3 items in that list and returns Jordan's results i.e. (12) ?

Thanks a lot !

Gengyang


From rosuav at gmail.com  Tue Nov 24 05:14:19 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 24 Nov 2015 21:14:19 +1100
Subject: Returning a result from 3 items in a list
In-Reply-To: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
Message-ID: <CAPTjJmoZsAj_WL4vEcAWQQ=Xe5rRNjO=dknKYSHmiVsbrjiJJA@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:04 PM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> Here's a dictionary with 3 values :
>
> results = {
>   "gengyang": 14,
>   "ensheng": 13,
>   "jordan": 12
> }
>
> How do I define a function that takes the last of the 3 items in that list and returns Jordan's results i.e. (12) ?
>
> Thanks a lot !

If you want Jordan's result, that's easy:

result["jordan"]

But there's no concept of "the last" entry in a dict. They don't have
an order. Do you mean "the entry with the greatest key"? That could be
written thus:

result[max(result)]

because max(result) is the string "jordan".

Does either of those make sense for what you're doing?

ChrisA


From gengyangcai at gmail.com  Tue Nov 24 05:27:43 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 02:27:43 -0800 (PST)
Subject: Returning a result from 3 items in a list
In-Reply-To: <mailman.98.1448360068.2291.python-list@python.org>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <mailman.98.1448360068.2291.python-list@python.org>
Message-ID: <45b60b80-d6b7-423e-93b9-2ef4977fb368@googlegroups.com>

Strange, it gives me an error message when i type result["jordan"] or result[max(result)] though :

>>> results = { 
  "gengyang": 14, 
  "ensheng": 13, 
  "jordan": 12 
} 

>>> result["jordan"]
Traceback (most recent call last):
  File "<pyshell#27>", line 1, in <module>
    result["jordan"]
NameError: name 'result' is not defined

>>> result[max(result)]
Traceback (most recent call last):
  File "<pyshell#28>", line 1, in <module>
    result[max(result)]
NameError: name 'result' is not defined
>>> 


On Tuesday, November 24, 2015 at 6:14:43 PM UTC+8, Chris Angelico wrote:
> On Tue, Nov 24, 2015 at 9:04 PM, Cai Gengyang <gengyangcai at gmail.com> wrote:
> > Here's a dictionary with 3 values :
> >
> > results = {
> >   "gengyang": 14,
> >   "ensheng": 13,
> >   "jordan": 12
> > }
> >
> > How do I define a function that takes the last of the 3 items in that list and returns Jordan's results i.e. (12) ?
> >
> > Thanks a lot !
> 
> If you want Jordan's result, that's easy:
> 
> result["jordan"]
> 
> But there's no concept of "the last" entry in a dict. They don't have
> an order. Do you mean "the entry with the greatest key"? That could be
> written thus:
> 
> result[max(result)]
> 
> because max(result) is the string "jordan".
> 
> Does either of those make sense for what you're doing?
> 
> ChrisA


From __peter__ at web.de  Tue Nov 24 05:32:51 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 24 Nov 2015 11:32:51 +0100
Subject: Returning a result from 3 items in a list
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
Message-ID: <n31eco$eme$1@ger.gmane.org>

Cai Gengyang wrote:

> Here's a dictionary with 3 values :
> 
> results = {
>   "gengyang": 14,
>   "ensheng": 13,
>   "jordan": 12
> }
> 
> How do I define a function that takes the last of the 3 items in that list
> and returns Jordan's results i.e. (12) ?
> 
> Thanks a lot !

You can access the last item in a *list* with items[-1]:

>>> results = [
... ("gengyang", 14),
... ("ensheng", 13),
... ("jordan", 12)
... ]
>>> results[-1]
('jordan', 12)

A *dict* is unordered (the order is undefined, to be exact), so there is no 
"last" item. For the rare case when you need both order and fast lookup 
there's collections.OrderedDict:

>>> results = collections.OrderedDict([
... ("gengyang", 14),
... ("ensheng", 13),
... ("jordan", 12)
... ])

Get the last value non-destructively:

>>> results[next(reversed(results))] # is there a less tedious way?
12

Get the last pair, removing it from the dictionary:

>>> results.popitem(last=True)
('jordan', 12)
>>> "jordan" in results
False




From __peter__ at web.de  Tue Nov 24 05:35:12 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 24 Nov 2015 11:35:12 +0100
Subject: Returning a result from 3 items in a list
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <mailman.98.1448360068.2291.python-list@python.org>
 <45b60b80-d6b7-423e-93b9-2ef4977fb368@googlegroups.com>
Message-ID: <n31egv$eme$2@ger.gmane.org>

Cai Gengyang wrote:

> Strange, it gives me an error message when i type result["jordan"] or
> result[max(result)] though :
> 
>>>> results = {
>   "gengyang": 14,
>   "ensheng": 13,
>   "jordan": 12
> }
> 
>>>> result["jordan"]
> Traceback (most recent call last):
>   File "<pyshell#27>", line 1, in <module>
>     result["jordan"]
> NameError: name 'result' is not defined

Yeah, the error message really should be

"NameError: name 'result' is not defined; did you mean 'results'?"

;)



From gengyangcai at gmail.com  Tue Nov 24 05:47:44 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 02:47:44 -0800 (PST)
Subject: Returning a result from 3 items in a list
In-Reply-To: <mailman.100.1448361611.2291.python-list@python.org>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <mailman.98.1448360068.2291.python-list@python.org>
 <45b60b80-d6b7-423e-93b9-2ef4977fb368@googlegroups.com>
 <mailman.100.1448361611.2291.python-list@python.org>
Message-ID: <16cbc004-c22f-492d-9f75-94e14374616d@googlegroups.com>

Yup, thanks a lot ... it works now !

>>> results = {
  "gengyang": 14,
  "ensheng": 13,
  "jordan": 12
  }
>>> results["jordan"]
12


On Tuesday, November 24, 2015 at 6:40:26 PM UTC+8, Peter Otten wrote:
> Cai Gengyang wrote:
> 
> > Strange, it gives me an error message when i type result["jordan"] or
> > result[max(result)] though :
> > 
> >>>> results = {
> >   "gengyang": 14,
> >   "ensheng": 13,
> >   "jordan": 12
> > }
> > 
> >>>> result["jordan"]
> > Traceback (most recent call last):
> >   File "<pyshell#27>", line 1, in <module>
> >     result["jordan"]
> > NameError: name 'result' is not defined
> 
> Yeah, the error message really should be
> 
> "NameError: name 'result' is not defined; did you mean 'results'?"
> 
> ;)


From eryksun at gmail.com  Tue Nov 24 05:53:21 2015
From: eryksun at gmail.com (eryksun)
Date: Tue, 24 Nov 2015 04:53:21 -0600
Subject: Persistent api-ms-win-crt-runtime-i1-1-0.dll start up error
In-Reply-To: <201511240954.tAO9sJHh007647@fido.openend.se>
References: <979fb56bd7b09c3a8944e56bbcc0c481@ankara.edu.tr>
 <201511240954.tAO9sJHh007647@fido.openend.se>
Message-ID: <CACL+1au2eWFqjtc_PbGvaqxhU4N2CtZx93VPcXDMH3xSWxSgVw@mail.gmail.com>

On Tue, Nov 24, 2015 at 3:54 AM, Laura Creighton <lac at openend.se> wrote:
> In a message of Tue, 24 Nov 2015 10:56:32 +0200, Tolga.Karabiyikoglu at ankara.edu
>
>>The question is i am receiving 'api-ms-win-crt-runtime-i1-1-0.dll is
>>missing' error on the start up.
>
> You appear to have this problem.
>
> https://bugs.python.org/issue25223
>
> Installing http://www.microsoft.com/en-us/download/details.aspx?id=48234
> directly seems to fix it.

For Vista the Universal CRT update requires service pack 2:

http://windows.microsoft.com/en-US/windows-vista/Learn-how-to-install-Windows-Vista-Service-Pack-2-SP2


From gengyangcai at gmail.com  Tue Nov 24 06:04:09 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 03:04:09 -0800 (PST)
Subject: Getting math scores (Dictionary inside dictionary)
Message-ID: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>

results = {
  "gengyang": { "maths": 10, "english": 15},
  "ensheng": {"maths": 12, "english": 10},
  "jordan": {"maths": 9, "english": 13}
  }

How do you get gengyang's maths scores ?

Thank you ...


From rosuav at gmail.com  Tue Nov 24 06:05:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 24 Nov 2015 22:05:04 +1100
Subject: Returning a result from 3 items in a list
In-Reply-To: <n31egv$eme$2@ger.gmane.org>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <mailman.98.1448360068.2291.python-list@python.org>
 <45b60b80-d6b7-423e-93b9-2ef4977fb368@googlegroups.com>
 <n31egv$eme$2@ger.gmane.org>
Message-ID: <CAPTjJmqf4jc4Q+penE1Upyvp39=F7K-iQkHb+72CP1woHPzXLA@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:35 PM, Peter Otten <__peter__ at web.de> wrote:
> Yeah, the error message really should be
>
> "NameError: name 'result' is not defined; did you mean 'results'?"
>
> ;)

Heh. Yes, that was my fault. Sorry Cai! it should have been
results["jordan"], as you figured out.

ChrisA


From gengyangcai at gmail.com  Tue Nov 24 06:06:44 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 03:06:44 -0800 (PST)
Subject: Returning a result from 3 items in a list
In-Reply-To: <mailman.102.1448363112.2291.python-list@python.org>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <mailman.98.1448360068.2291.python-list@python.org>
 <45b60b80-d6b7-423e-93b9-2ef4977fb368@googlegroups.com>
 <n31egv$eme$2@ger.gmane.org>
 <mailman.102.1448363112.2291.python-list@python.org>
Message-ID: <22e21276-50f6-49c8-925e-3d33284b49cb@googlegroups.com>

Its cool ... No problem 

On Tuesday, November 24, 2015 at 7:05:25 PM UTC+8, Chris Angelico wrote:
> On Tue, Nov 24, 2015 at 9:35 PM, Peter Otten <__peter__ at web.de> wrote:
> > Yeah, the error message really should be
> >
> > "NameError: name 'result' is not defined; did you mean 'results'?"
> >
> > ;)
> 
> Heh. Yes, that was my fault. Sorry Cai! it should have been
> results["jordan"], as you figured out.
> 
> ChrisA



From xapwing at gmail.com  Tue Nov 24 06:10:47 2015
From: xapwing at gmail.com (Arie van Wingerden)
Date: Tue, 24 Nov 2015 12:10:47 +0100
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
Message-ID: <CADkALSF0ywARkJHAOZ76ys7xXQuYmAw7ntzFYRuPhVJ3kHr0zQ@mail.gmail.com>

print((results["gengyang"])["maths"])

2015-11-24 12:04 GMT+01:00 Cai Gengyang <gengyangcai at gmail.com>:

> results = {
>   "gengyang": { "maths": 10, "english": 15},
>   "ensheng": {"maths": 12, "english": 10},
>   "jordan": {"maths": 9, "english": 13}
>   }
>
> How do you get gengyang's maths scores ?
>
> Thank you ...
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From gengyangcai at gmail.com  Tue Nov 24 06:22:41 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 19:22:41 +0800
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <CADkALSF0ywARkJHAOZ76ys7xXQuYmAw7ntzFYRuPhVJ3kHr0zQ@mail.gmail.com>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
 <CADkALSF0ywARkJHAOZ76ys7xXQuYmAw7ntzFYRuPhVJ3kHr0zQ@mail.gmail.com>
Message-ID: <CAE8stXxeq3RUHJF+-g==8+e8iPZzw6WZE=Baj0o_pOQAxk61-w@mail.gmail.com>

Great, it works! Thanks a lot ..

>>> results = {
  "gengyang": { "maths": 10, "english": 15},
  "ensheng": {"maths": 12, "english": 10},
  "jordan": {"maths": 9, "english": 13}
  }

>>> print((results["gengyang"])["maths"])
10

On Tue, Nov 24, 2015 at 7:10 PM, Arie van Wingerden <xapwing at gmail.com>
wrote:

> print((results["gengyang"])["maths"])
>
> 2015-11-24 12:04 GMT+01:00 Cai Gengyang <gengyangcai at gmail.com>:
>
>> results = {
>>   "gengyang": { "maths": 10, "english": 15},
>>   "ensheng": {"maths": 12, "english": 10},
>>   "jordan": {"maths": 9, "english": 13}
>>   }
>>
>> How do you get gengyang's maths scores ?
>>
>> Thank you ...
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
>
>


From steve at pearwood.info  Tue Nov 24 06:25:56 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 24 Nov 2015 22:25:56 +1100
Subject: tuples in conditional assignment
References: <mailman.36.1447434002.19880.python-list@python.org>
 <mailman.83.1448335555.2291.python-list@python.org>
Message-ID: <56544946$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Tue, 24 Nov 2015 02:25 pm, George Trojan wrote:

> The following code has bitten me recently:
> 
>  >>> t=(0,1)
>  >>> x,y=t if t else 8, 9
>  >>> print(x, y)
> (0, 1) 9
> 
> I was assuming that a comma has the highest order of evaluation, that is
> the expression 8, 9 should make a tuple. Why this is not the case?

I'm not sure what sort of answer you are looking for. Why does anything have
the precedence it has?

Making assumptions about the comma's precedence in that way seems unsafe to
me. Consider that function(a, b, c, d) is a function call with four
arguments, NOT a single 4-tuple argument. And:

py> 1, 2, 3 * 2  # expecting (1, 2, 3, 1, 2, 3)
(1, 2, 6)

So there's plenty of evidence that the comma has a very low order of
evaluation, not the highest, and it seems remarkably unsafe to assume the
opposite. Fortunately, it is very simple to test these things out at the
interactive interpreter. I cannot imagine doing any Python programming
without having a Python shell open and ready for me to try out code
snippets.



-- 
Steven



From steve at pearwood.info  Tue Nov 24 06:28:20 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 24 Nov 2015 22:28:20 +1100
Subject: Getting math scores (Dictionary inside dictionary)
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
Message-ID: <565449d6$0$1593$c3e8da3$5496439d@news.astraweb.com>

On Tue, 24 Nov 2015 10:04 pm, Cai Gengyang wrote:

> results = {
>   "gengyang": { "maths": 10, "english": 15},
>   "ensheng": {"maths": 12, "english": 10},
>   "jordan": {"maths": 9, "english": 13}
>   }
> 
> How do you get gengyang's maths scores ?

Break the problem into two steps:

- get Gengyang's scores;

- then get the maths score:

scores = results['gengyang']
maths_score = scores['maths']


Now you can simplify the process:

maths_score = results['gengyang']['maths']



-- 
Steven



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 06:36:11 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 12:36:11 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
Message-ID: <56544BAB.9020709@rece.vub.ac.be>

Op 19-11-15 om 00:22 schreef Chris Angelico:
> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc at freeuk.com> wrote:
>> On 18/11/2015 22:11, Ian Kelly wrote:
>>>
>>> On Wed, Nov 18, 2015 at 2:08 PM, fl <rxjwg98 at gmail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I have tried the below function and find that it can remember the
>>>> previous
>>>> setting value to 'val'. I think the second parameter has something on
>>>> this
>>>> effect, but I don't know the name and function of '=[]' in this
>>>> application.
>>>>
>>>> Could you explain a little to me?
>>>> Thanks,
>>>>
>>>>
>>>> def eList(val, list0=[]):
>>>>      list0.append(val)
>>>>      return list0
>>>> list1 = eList(12)
>>>> list1 = eList('a')
>>>
>>>
>>> The list0 parameter has a default value, which is [], an initially
>>> empty list. The default value is evaluated when the function is
>>> defined, not when it is called, so the same list object is used each
>>> time and changes to the list are consequently retained between calls.
>>
>>
>> That is really bizarre behaviour.
>>
>> So, looking at some source code, a default value for certain types is only
>> certain to be that value for the very first call of that function?
> 
> On the contrary, it is certain always to be that exact object.

No, he is talking about the value. Since the object can be mutated
and thus have an other value, his statement seems correct.

-- 
Antoon.



From rosuav at gmail.com  Tue Nov 24 07:07:34 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 24 Nov 2015 23:07:34 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <56544BAB.9020709@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
Message-ID: <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>

On Tue, Nov 24, 2015 at 10:36 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
>>> So, looking at some source code, a default value for certain types is only
>>> certain to be that value for the very first call of that function?
>>
>> On the contrary, it is certain always to be that exact object.
>
> No, he is talking about the value. Since the object can be mutated
> and thus have an other value, his statement seems correct.

With mutable objects, you can *never* depend on their values. Any time
ANY byte code gets executed, the value could change. That's why I have
never said anything about *values* of arg defaults - what you're
promised is that the *object* will be the same (so, I'm looking at its
identity, rather than its value). So it's not even certain to be that
value even for the first call:

def create_user(name, email, creation_time=datetime.datetime.now()):

Looks perfectly reasonable, right? And with late binding, sure! But
with early binding, this will probably NEVER be what you want. But
what if you have an object that always stringifies the current time?

class Now:
    def __init__(self, fmt):
        self.fmt = fmt
    def __repr__(self):
        return datetime.datetime.now().strftime(self.fmt)

def create_user(name, email, creation_time=Now("%Y%m%d%H%M%S")):

Voila! An object whose value dynamically represents the notion of
"Now", but where it makes fine sense to have the same object used
every time. Since the value changes every second, it (probably) won't
even have that value for the first call, yet the behaviour will be
correct.

His statement is still incorrect, in that the value is NEVER certain,
but the identity is ALWAYS certain. It happens to be the case for the
one example of lists that get mutated only in the function. It's about
as accurate as the statement that Python is pass-by-value for integers
but pass-by-reference for dictionaries.

ChrisA


From breamoreboy at yahoo.co.uk  Tue Nov 24 07:15:48 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 24 Nov 2015 12:15:48 +0000
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
Message-ID: <n31kdn$gvf$1@ger.gmane.org>

On 24/11/2015 11:04, Cai Gengyang wrote:
> results = {
>    "gengyang": { "maths": 10, "english": 15},
>    "ensheng": {"maths": 12, "english": 10},
>    "jordan": {"maths": 9, "english": 13}
>    }
>
> How do you get gengyang's maths scores ?
>
> Thank you ...
>

One way is to delete the scores for ensheng and jordan, only leaving 
those for gengyang, then extract the maths score.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From xapwing at gmail.com  Tue Nov 24 07:23:56 2015
From: xapwing at gmail.com (Arie van Wingerden)
Date: Tue, 24 Nov 2015 13:23:56 +0100
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <n31kdn$gvf$1@ger.gmane.org>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
 <n31kdn$gvf$1@ger.gmane.org>
Message-ID: <CADkALSEPW9BNW6taj3hh6h3YbzWvgWZ2JCyj53oqN_Oh_GjY+w@mail.gmail.com>

Hi Mark, what use would that have? Please show your code ...

2015-11-24 13:15 GMT+01:00 Mark Lawrence <breamoreboy at yahoo.co.uk>:

> On 24/11/2015 11:04, Cai Gengyang wrote:
>
>> results = {
>>    "gengyang": { "maths": 10, "english": 15},
>>    "ensheng": {"maths": 12, "english": 10},
>>    "jordan": {"maths": 9, "english": 13}
>>    }
>>
>> How do you get gengyang's maths scores ?
>>
>> Thank you ...
>>
>>
> One way is to delete the scores for ensheng and jordan, only leaving those
> for gengyang, then extract the maths score.
>
> --
> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.
>
> Mark Lawrence
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 07:38:01 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 13:38:01 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
 <n2j98r$o9c$1@dont-email.me>
 <mailman.440.1447898362.16136.python-list@python.org>
 <n2kcdn$lq0$1@dont-email.me>
 <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <56545A29.1040101@rece.vub.ac.be>

Op 19-11-15 om 13:45 schreef Steven D'Aprano:
> On Thu, 19 Nov 2015 10:41 pm, BartC wrote:
> 
> 
>> I expect the version with the default argument to be
>> exactly the same as the last lot of calls, namely for:
>>
>> fn()
>> fn()
>> fn()
>>
>> to be equivalent to:
>>
>> temp=[]
>> fn(temp)
>> temp=[]
>> fn(temp)
>> temp=[]
>> fn(temp)
> 
> Why on earth would you expect that?
> 
> I don't mean that it isn't sometimes useful. Of course it is sometimes
> useful, there's no doubt about that. But why would you expect the language
> to default to the *slow*, *expensive*, *complicated* behaviour instead of
> the *fast*, *cheap*, *simple* behaviour?

I would say because it is better understandable. The way default value
behave now, is just a little less surprising as when the following segment
of code would print: [1]

a = []
a.append(1)
b = []
print b

Let us not forget that the tutorial talks about Default Argument *Values*.
And also the language reference talks about precomputed *values*. What
we really get is a precomputed object.

> You already have one way to set the argument to a fresh list every time you
> call the function: put the code you want executed inside the body of the
> function. There's no need for a *second* way to get the same result.

Which is beside the point. The point is understandability.

> But if you want the default value to be evaluated exactly once, and once
> only, there is no real alternative to early binding. You could use a global
> variable, of course, but that is no solution -- that's a problem waiting to
> happen.

No more than the situation we have now. The situation we have now is a problem
waiting to happen too. Which is confirmed again and again. You are stacking
the deck by calling a possible alternative "a problem waiting to happen" while
ignoring the problems that happen with the current situation.




From antoon.pardon at rece.vub.ac.be  Tue Nov 24 07:48:25 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 13:48:25 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
Message-ID: <56545C99.9020902@rece.vub.ac.be>

Op 24-11-15 om 13:07 schreef Chris Angelico:
> On Tue, Nov 24, 2015 at 10:36 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>>>> So, looking at some source code, a default value for certain types is only
>>>> certain to be that value for the very first call of that function?
>>>
>>> On the contrary, it is certain always to be that exact object.
>>
>> No, he is talking about the value. Since the object can be mutated
>> and thus have an other value, his statement seems correct.
> 
> With mutable objects, you can *never* depend on their values. Any time
> ANY byte code gets executed, the value could change. That's why I have
> never said anything about *values* of arg defaults.

Yes you have. You haven't mentioned them yourself. But when you contradict
the statement of someone and that person talked about values, then in
contradicting that statement you said something about values.

You then switching to talking about objects, just gives the impression
that object is a synonym for value.

-- 
Antoon


From marko at pacujo.net  Tue Nov 24 07:57:34 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 24 Nov 2015 14:57:34 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
Message-ID: <874mgbpnb5.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> You then switching to talking about objects, just gives the impression
> that object is a synonym for value.

It isn't?


Marko


From gengyangcai at gmail.com  Tue Nov 24 08:25:28 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Tue, 24 Nov 2015 05:25:28 -0800 (PST)
Subject: Finding scores from a list
Message-ID: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>


results = [
{"id": 1, "name": "ensheng", "score": 10},
{"id": 2, "name": "gengyang", "score": 12},
{"id": 3, "name": "jordan", "score": 5},
]

I want to find gengyang's score. This is what I tried :

>>> print((results["gengyang"])["score"])

but I got an error message instead :

Traceback (most recent call last):
  File "<pyshell#62>", line 1, in <module>
    print((results["gengyang"])["score"])
TypeError: list indices must be integers, not str

Any ideas how to solve this? Thank you ..


From breamoreboy at yahoo.co.uk  Tue Nov 24 08:30:23 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 24 Nov 2015 13:30:23 +0000
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <CADkALSEPW9BNW6taj3hh6h3YbzWvgWZ2JCyj53oqN_Oh_GjY+w@mail.gmail.com>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
 <n31kdn$gvf$1@ger.gmane.org>
 <CADkALSEPW9BNW6taj3hh6h3YbzWvgWZ2JCyj53oqN_Oh_GjY+w@mail.gmail.com>
Message-ID: <n31opi$miu$1@ger.gmane.org>

On 24/11/2015 12:23, Arie van Wingerden wrote:
> Hi Mark, what use would that have? Please show your code ...
>
> 2015-11-24 13:15 GMT+01:00 Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
>> On 24/11/2015 11:04, Cai Gengyang wrote:
>>
>>> results = {
>>>     "gengyang": { "maths": 10, "english": 15},
>>>     "ensheng": {"maths": 12, "english": 10},
>>>     "jordan": {"maths": 9, "english": 13}
>>>     }
>>>
>>> How do you get gengyang's maths scores ?
>>>
>>> Thank you ...
>>>
>>>
>> One way is to delete the scores for ensheng and jordan, only leaving those
>> for gengyang, then extract the maths score.
>>
>> --
>> My fellow Pythonistas, ask not what our language can do for you, ask
>> what you can do for our language.
>>
>> Mark Lawrence
>>
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>

1) I was being facetious.
2) How many times do people have to be asked not to top post here before 
they stop top posting?
3) I only have two things to say so this is superfluous.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From marko at pacujo.net  Tue Nov 24 08:41:58 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 24 Nov 2015 15:41:58 +0200
Subject: Getting math scores (Dictionary inside dictionary)
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
 <n31kdn$gvf$1@ger.gmane.org>
 <CADkALSEPW9BNW6taj3hh6h3YbzWvgWZ2JCyj53oqN_Oh_GjY+w@mail.gmail.com>
 <mailman.111.1448371835.2291.python-list@python.org>
Message-ID: <87poyzo6op.fsf@elektro.pacujo.net>

Mark Lawrence <breamoreboy at yahoo.co.uk>:

> 1) I was being facetious.
> 2) How many times do people have to be asked not to top post here
> before they stop top posting?
> 3) I only have two things to say so this is superfluous.

Mark, it may not be your objective, but you really are poisoning the
atmosphere here.


Marko


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 08:43:33 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 14:43:33 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
Message-ID: <56546985.8060704@rece.vub.ac.be>

Op 20-11-15 om 01:27 schreef Ned Batchelder:
> On Thursday, November 19, 2015 at 7:11:52 PM UTC-5, BartC wrote:
>> On 19/11/2015 22:55, Michael Torrie wrote:
>>> On 11/19/2015 02:21 PM, BartC wrote:
>>>> (Python returns 42; so that means my languages are more dynamic than
>>>> Python? That's hard to believe!)
>>>
>>> It tells me your language does late binding for default arguments, which
>>> does mean the default argument can dynamically change at call time,
>>> which would surprise me if I didn't know about it.  Either form of
>>> binding is acceptable, and I don't think it makes a language more or
>>> less dynamic.
>>
>> You get the expression that is specified, which can give different 
>> values at different times unless it involves only constants.
>>
>> It can't be exactly the same as writing an identical expression in place 
>> of the missing argument, as apparently different scopes come into play 
>> if names are involved.
>>
>> However I mainly use them for constant values. And [] is a constant 
>> value in my opinion.
>>
>> -- 
>> Bartc
> 
> You are not alone in being surprised by how mutable default values work.
> It is a topic that comes up in every "What's Bad About Python" discussion,
> and is a common question from new users of the language.
> 
> I can understand how you would view [] as a constant value.  It's true that
> it is an expression that produces a consistent value each time it is
> evaluated.  But that value is a list, and lists are mutable.  The examples
> here all use the .append() method on that value, which changes it.

I think that part of the problem is, that [] is not a constant object. So
that when you see a line like

    ls = []

It behaves more lke

    ls = [].copy()

than what you would expect with the normal python semantics.

-- 
Antoon



From breamoreboy at yahoo.co.uk  Tue Nov 24 08:44:47 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 24 Nov 2015 13:44:47 +0000
Subject: Finding scores from a list
In-Reply-To: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
References: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
Message-ID: <n31pkh$8ic$1@ger.gmane.org>

On 24/11/2015 13:25, Cai Gengyang wrote:
>
> results = [
> {"id": 1, "name": "ensheng", "score": 10},
> {"id": 2, "name": "gengyang", "score": 12},
> {"id": 3, "name": "jordan", "score": 5},
> ]
>
> I want to find gengyang's score. This is what I tried :
>
>>>> print((results["gengyang"])["score"])
>
> but I got an error message instead :
>
> Traceback (most recent call last):
>    File "<pyshell#62>", line 1, in <module>
>      print((results["gengyang"])["score"])
> TypeError: list indices must be integers, not str
>
> Any ideas how to solve this? Thank you ..
>

Please read and digest the TypeError.  There is a very strong hint in 
there, follow it.  Compare the type of your data structure `results` 
with the one you've used earlier today.  Spot the difference?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 08:48:34 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 14:48:34 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <n2l3u5$i6a$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me> <n2l3u5$i6a$1@ger.gmane.org>
Message-ID: <56546AB2.1080806@rece.vub.ac.be>

Op 19-11-15 om 19:20 schreef Mark Lawrence:
> On 19/11/2015 17:30, BartC wrote:
>> On 19/11/2015 16:01, Steven D'Aprano wrote:
>>> On Fri, 20 Nov 2015 12:19 am, BartC wrote:
>>
>>> You know, for somebody who claims to design and implement your own
>>> languages, you sometimes go to a remarkable effort to claim to be a
>>> dummy.
>>> You write your own interpreter, but can't understand early versus late
>>> binding? I don't think so.
>>
>> No I don't; so? Maybe my interpreter can do its thing without being
>> aware that what it's doing has been called 'late binding' or 'early
>> binding' by someone else.
>>
>> At least its default values work as expected!
>>
> 
> Python's default values work exactly as I expect as the subject has been debated at least twice a year
> on c.l.py for the 15 or so years that I've been using Python.  If your expectations are clearly wrong,
> that is your problem and your problem alone. Absolution to your problem is another language that does
> meet all of your expectations, but as there is never a "one size fits all" the only one that I can
> think of is your own, whatever that is called.

Nonsense. The fact that an experienced programmer, gets to be extremely familiar with some languages
and thus gets his expectations adapted, doesn't mean that there is something wrong with what newby's
intuitively expect to happen.

On the contrary, the regularity with how this subjects keep coming up, is an indication that this
is a problem with python.

-- 
Antoon.


From __peter__ at web.de  Tue Nov 24 08:50:01 2015
From: __peter__ at web.de (Peter Otten)
Date: Tue, 24 Nov 2015 14:50:01 +0100
Subject: Finding scores from a list
References: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
Message-ID: <n31pu9$b1f$1@ger.gmane.org>

Cai Gengyang wrote:

> 
> results = [
> {"id": 1, "name": "ensheng", "score": 10},
> {"id": 2, "name": "gengyang", "score": 12},
> {"id": 3, "name": "jordan", "score": 5},
> ]
> 
> I want to find gengyang's score. This is what I tried :
> 
>>>> print((results["gengyang"])["score"])
> 
> but I got an error message instead :
> 
> Traceback (most recent call last):
>   File "<pyshell#62>", line 1, in <module>
>     print((results["gengyang"])["score"])
> TypeError: list indices must be integers, not str
> 
> Any ideas how to solve this? Thank you ..

As the outer container is a list you have to provide an index:

results[1]["score"]

You can also search for a matching item:

for result in results:
   if result["name"] == "gengyang":
       print(result["score"])

but when the list grows performance will suffer.

General note: you will have a better experience learning Python when you 
read some introductory text first, to get the big picture.



From rosuav at gmail.com  Tue Nov 24 09:00:28 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 01:00:28 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <56546985.8060704@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
Message-ID: <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>

On Wed, Nov 25, 2015 at 12:43 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> I think that part of the problem is, that [] is not a constant object. So
> that when you see a line like
>
>     ls = []
>
> It behaves more lke
>
>     ls = [].copy()
>
> than what you would expect with the normal python semantics.

You're still thinking in terms of [] being a literal. It isn't; the
docs describe it as "list display", and it's closer to:

ls = list()

except that it doesn't look up the global name. Every time you call
open(), you expect it to open a fresh file handle, right? (Even if you
use the same file name.) And every time you call object(), you get a
new and unique sentinel object. It's the same with list(), and it's
the same with square brackets as well.

Start thinking of it as a constructor call rather than a literal, and
you'll get past most of the confusion.

ChrisA


From luisjosenovoa at gmail.com  Tue Nov 24 09:04:14 2015
From: luisjosenovoa at gmail.com (LJ)
Date: Tue, 24 Nov 2015 06:04:14 -0800 (PST)
Subject: Multiprocessing PyPy-CPython
Message-ID: <a2205fed-2a08-41f0-bfca-85811b65d569@googlegroups.com>

Hi everyone.

Im trying to solve some problems in parallel using the multiprocessing module in Python 2.7. A general model is built using CPython and then the subproblems are solved in parallel returning results in a queue. This is currently working fine. I would like to solve the subproblems using PyPy to increase speed.
I found http://project-trains.tumblr.com/post/102076598295/multiprocessing-pypy , but there it says that the procedure only works with CPython 3.4.

I wonder is there is any clean direct way to do this.

Appreciate any help.


From denismfmcmahon at gmail.com  Tue Nov 24 09:07:31 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Tue, 24 Nov 2015 14:07:31 -0000 (UTC)
Subject: Returning a result from 3 items in a list
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
Message-ID: <n31qv3$4en$1@dont-email.me>

On Tue, 24 Nov 2015 02:04:56 -0800, Cai Gengyang wrote:

> Here's a dictionary with 3 values :
> 
> results = {
>   "gengyang": 14,
>   "ensheng": 13, "jordan": 12
> }
> 
> How do I define a function that takes the last of the 3 items in that
> list and returns Jordan's results i.e. (12) ?

You open a web browser and google for "python dictionary"

-- 
Denis McMahon, denismfmcmahon at gmail.com


From denismfmcmahon at gmail.com  Tue Nov 24 09:09:14 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Tue, 24 Nov 2015 14:09:14 -0000 (UTC)
Subject: Getting math scores (Dictionary inside dictionary)
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
Message-ID: <n31r29$4en$2@dont-email.me>

On Tue, 24 Nov 2015 03:04:09 -0800, Cai Gengyang wrote:

> results = {
>   "gengyang": { "maths": 10, "english": 15},
>   "ensheng": {"maths": 12, "english": 10}, "jordan": {"maths": 9,
>   "english": 13}
>   }
> 
> How do you get gengyang's maths scores ?

I refer to my previous answer. Open a web browser and google "python 
dictionary"

-- 
Denis McMahon, denismfmcmahon at gmail.com


From bc at freeuk.com  Tue Nov 24 09:12:39 2015
From: bc at freeuk.com (BartC)
Date: Tue, 24 Nov 2015 14:12:39 +0000
Subject: Finding scores from a list
In-Reply-To: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
References: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
Message-ID: <n31r4d$a6g$1@dont-email.me>

On 24/11/2015 13:25, Cai Gengyang wrote:
>
> results = [
> {"id": 1, "name": "ensheng", "score": 10},
> {"id": 2, "name": "gengyang", "score": 12},
> {"id": 3, "name": "jordan", "score": 5},
> ]
>
> I want to find gengyang's score. This is what I tried :
>
>>>> print((results["gengyang"])["score"])
>
> but I got an error message instead :
>
> Traceback (most recent call last):
>    File "<pyshell#62>", line 1, in <module>
>      print((results["gengyang"])["score"])
> TypeError: list indices must be integers, not str
>
> Any ideas how to solve this? Thank you ..

Your new results type is a list of dicts.

Lists are indexed by a number. That will be results[1] for the dict 
relevant to "gengyang" (not even the 2 of the "id", because lists start 
counting at 0).

To find the entry for particular name, you have to search for it (for a 
list entry where the dict key "name" gives you the value you expect, ie. 
"gengyang" in this example).

So a dict of dicts was a better idea.

-- 
Bartc


From ned at nedbatchelder.com  Tue Nov 24 09:18:19 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 06:18:19 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <874mgbpnb5.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
Message-ID: <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>

On Tuesday, November 24, 2015 at 7:57:54 AM UTC-5, Marko Rauhamaa wrote:
> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
> 
> > You then switching to talking about objects, just gives the impression
> > that object is a synonym for value.
> 
> It isn't?

We are tangled up in another terminology conflict.  The word "value" is
being used in two different senses. It's understandable that this results
in confusion.  Neither use is incorrect, we just have to understand that
there are multiple meanings, and clarify where the meaning is uncertain.

1) In English, "value" means something like, what is this equal to? There
isn't another good word to use in place of "value" here. We might awkwardly
use the word "equivalence" as a synonym.  I'll use the word "evalue" (short
for "equal value" or "equivalence value" or "English value"). The ==
operator is useful for testing whether two values are "the same evalue".
In this sense, the expression "[]" always evaluates to the same value,
an empty list:

    >>> a = []
    >>> b = []
    >>> a == b
    True

2) In Python, "value" means, what object does a name refer to, or what
object did an evaluation produce.  We could use "referent" as a
synonym for this meaning.  The Python operator "is" tests whether two
values are the same referent, or, the same object. In this sense, "[]" 
always evaluates to a different value, because you get a new empty list
each time:

    >>> a = []
    >>> b = []
    >>> a is b
    False

Mutable objects are complicated because the same referent (object) can
change its evalue over time.

The confusion over mutable default arguments arises because the
defaulted argument always gets the same referent, but it might not
always be the same evalue.

--Ned.


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 09:18:43 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 15:18:43 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <565471C3.3060305@rece.vub.ac.be>

Op 20-11-15 om 02:05 schreef Steven D'Aprano:
> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
> 
>> On 19/11/2015 16:01, Steven D'Aprano wrote:
> [...]
> 
>> The whole concept of 'mutable' default is alien to me. A default is just 
>> a convenient device to avoid having to write:
>>
>>    fn(0) or fn("") or fn([])
> 
> Says who?
> 
> Here's another use for function defaults, as static storage:
> 
> 
> # Ackermann's function
> def ack(m, n, _memo={}):
>     key = m, n
>     if key not in _memo:
>         if m==0: v = n + 1
>         elif n==0: v = ack(m-1, 1)
>         else: v = ack(m-1, ack(m, n-1))
>         _memo[key] = v
>     return _memo[key]
> 
> 
> This is a quick and easy way to memoise a function which would otherwise be
> horribly slow. And it only works because _memo is bound to a mutable object
> once, and once only.

I think this is the worst kind of example you can give in defense for this
kind of behaviour. Because you are defining a function as having three parameters
where it really has only two. You really don't want this function to be called
with that third parameter.

Secondly, because we have decorators now, it really is not a good idea to define
your function with the memoization in the body functionality.

Thirdly your use with a default argument would go horribly wrong, should we
try to use it in the decorator definition.

-- 
Antoon.



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 09:24:55 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 15:24:55 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
Message-ID: <56547337.4000709@rece.vub.ac.be>

Op 24-11-15 om 15:00 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 12:43 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> I think that part of the problem is, that [] is not a constant object. So
>> that when you see a line like
>>
>>     ls = []
>>
>> It behaves more lke
>>
>>     ls = [].copy()
>>
>> than what you would expect with the normal python semantics.
> 
> You're still thinking in terms of [] being a literal. It isn't; the
> docs describe it as "list display", and it's closer to:
> 
> ls = list()

No I am not. The distinction you are making here is unimportant for
the point I am making. And that is that although

    v = ()
and
    v = []

look very similar. They behave differently.

> except that it doesn't look up the global name. Every time you call
> open(), you expect it to open a fresh file handle, right? (Even if you
> use the same file name.) And every time you call object(), you get a
> new and unique sentinel object. It's the same with list(), and it's
> the same with square brackets as well.
> 
> Start thinking of it as a constructor call rather than a literal, and
> you'll get past most of the confusion.

That doesn't change the fact it does look like a literal and not like
a constructor.

-- 
Antoon.


From breamoreboy at yahoo.co.uk  Tue Nov 24 09:28:57 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Tue, 24 Nov 2015 14:28:57 +0000
Subject: Returning a result from 3 items in a list
In-Reply-To: <n31qv3$4en$1@dont-email.me>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <n31qv3$4en$1@dont-email.me>
Message-ID: <n31s7c$lba$1@ger.gmane.org>

On 24/11/2015 14:07, Denis McMahon wrote:
> On Tue, 24 Nov 2015 02:04:56 -0800, Cai Gengyang wrote:
>
>> Here's a dictionary with 3 values :
>>
>> results = {
>>    "gengyang": 14,
>>    "ensheng": 13, "jordan": 12
>> }
>>
>> How do I define a function that takes the last of the 3 items in that
>> list and returns Jordan's results i.e. (12) ?
>
> You open a web browser and google for "python dictionary"
>

Ooh steady on old chap, surely you should have fitted the bib, done the 
spoon feeding and then changed the nappy?  That appears to me the 
preferred way of doing things nowadays on c.l.py, rather than bluntly 
telling people not to be so bloody lazy.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From rosuav at gmail.com  Tue Nov 24 09:34:03 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 01:34:03 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <56547337.4000709@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
Message-ID: <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>

On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
>> Start thinking of it as a constructor call rather than a literal, and
>> you'll get past most of the confusion.
>
> That doesn't change the fact it does look like a literal and not like
> a constructor.

Then explain how this is a literal:

squares = [x*x for x in range(int(input("How far? ")))]

Or even a simple example like this:

coords = (randrange(10), randrange(10))

Neither of them is a literal, even though one of them isn't even
constructing a list. Tuples may be constant, but they still don't have
a literal form. (Constant folding can make them function the same way
literals do, though. If a tuple is constructed of nothing but
immutable constants - including an empty tuple - then CPython will
generally create a constant for the whole tuple and use that, rather
than manually constructing one every time. But the same is true of
other expressions involving nothing but constants.)

So if it (in your opinion) looks like a literal but isn't one, whose
fault is it? Yours or the language's? Not a rhetorical question.

ChrisA


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 09:34:15 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 15:34:15 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
Message-ID: <56547567.2090603@rece.vub.ac.be>

Op 20-11-15 om 13:12 schreef Ned Batchelder:
> On Friday, November 20, 2015 at 6:59:54 AM UTC-5, BartC wrote:
>> On 20/11/2015 01:05, Steven D'Aprano wrote:
>>> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
>>>
>>>> On 19/11/2015 16:01, Steven D'Aprano wrote:
>>> [...]
>>>
>>>> The whole concept of 'mutable' default is alien to me. A default is just
>>>> a convenient device to avoid having to write:
>>>>
>>>>     fn(0) or fn("") or fn([])
>>>
>>> Says who?
>>
>> People who want to avoid having to write:
>>
>>       fn(0) or fn("") or fn([])
> 
> I think we all understand by now that you are unhappy with what happens
> in Python with mutable defaults.  We get it.  You are not alone. Lots of
> people are surprised by this.  But it is how Python works.

May be you should get this message through to the python tribe, so that
they stop reacting as a stung horse each time someone finds something
bizarre with the language.

> I'm not sure what your goal is at this point.  Are you:
> 
>   1) still unsure what the behavior is, or 
>   2) trying to understand why it behaves that way, or
>   3) hoping to change Python, or
>   4) trying to convince us that your language is better, or
>   5) something else?

Maybe just have us recognize that some aspects of python indeed are bizarre.
That there is nothing wrong with him thinking so. After that he will have
to make up his mind whether this bizarre aspect is to big a hurdle for
using the language or not, because it seems unlikely to change.

-- 
Antoon.


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 09:38:26 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 15:38:26 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmo3vvVuRdb6T3Xk+sHKUAbixosSKK3_hOF5+CexQXtbvA@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <n2n46v$uj0$1@dont-email.me>
 <CAPTjJmo3vvVuRdb6T3Xk+sHKUAbixosSKK3_hOF5+CexQXtbvA@mail.gmail.com>
Message-ID: <56547662.6060708@rece.vub.ac.be>

Op 20-11-15 om 14:04 schreef Chris Angelico:
> On Fri, Nov 20, 2015 at 11:39 PM, BartC <bc at freeuk.com> wrote:
>> * The refusal to acknowledge that the def fn(a=[]) syntax is misleading.
>> (What value will a have when you call fn()? The true answer is that you
>> can't tell.)
> 
> It isn't misleading. The default value for the argument is set when
> the function is defined, and it is set to the *object* that results
> from evaluating the *expression* given. After that, the *object* is
> the one you will always get (barring shenanigans) if the argument is
> omitted. If the value of that object changes, it changes!

That you can perfectly explain what happens, doesn't contradict that
it is misleading. On the contrary, the fact that one needs all this
explanation in order to grasp what is happening, confirms that it
is misleading.

And you may be talking about objects here. The tutorial talks about
values.

> You keep expecting the *value* to be consistent. But what you actually
> get is that the *object* is consistent. It's virtually impossible to
> guarantee the former, in the face of mutable objects.

What is wrong with expecting the value to be consistent when the tutorial
talks about values?

-- 
Antoon.



From xapwing at gmail.com  Tue Nov 24 09:43:43 2015
From: xapwing at gmail.com (Arie van Wingerden)
Date: Tue, 24 Nov 2015 15:43:43 +0100
Subject: Getting math scores (Dictionary inside dictionary)
In-Reply-To: <87poyzo6op.fsf@elektro.pacujo.net>
References: <efdba2f0-8d09-4c83-b11c-62857e8ff20b@googlegroups.com>
 <n31kdn$gvf$1@ger.gmane.org>
 <CADkALSEPW9BNW6taj3hh6h3YbzWvgWZ2JCyj53oqN_Oh_GjY+w@mail.gmail.com>
 <mailman.111.1448371835.2291.python-list@python.org>
 <87poyzo6op.fsf@elektro.pacujo.net>
Message-ID: <CADkALSH=rJo7AVD-ZVLWgX1_er+i7TG+O-dnLt0Mp41g+8BBGw@mail.gmail.com>

2015-11-24 14:41 GMT+01:00 Marko Rauhamaa <marko at pacujo.net>:

> Mark Lawrence <breamoreboy at yahoo.co.uk>:
>
> > 1) I was being facetious.
> > 2) How many times do people have to be asked not to top post here
> > before they stop top posting?
> > 3) I only have two things to say so this is superfluous.
>
> Having posted only 2 times in this list I was not aware of the specific
religious mailing list book used here.
So please apologize :-)


From bc at freeuk.com  Tue Nov 24 09:43:43 2015
From: bc at freeuk.com (BartC)
Date: Tue, 24 Nov 2015 14:43:43 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
Message-ID: <n31suk$hi5$1@dont-email.me>

On 24/11/2015 14:18, Ned Batchelder wrote:
> On Tuesday, November 24, 2015 at 7:57:54 AM UTC-5, Marko Rauhamaa wrote:
>> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
>>
>>> You then switching to talking about objects, just gives the impression
>>> that object is a synonym for value.
>>
>> It isn't?

> 1) In English, "value" means something like, what is this equal to? There
> isn't another good word to use in place of "value" here. We might awkwardly
> use the word "equivalence" as a synonym.  I'll use the word "evalue" (short
> for "equal value" or "equivalence value" or "English value"). The ==
> operator is useful for testing whether two values are "the same evalue".
> In this sense, the expression "[]" always evaluates to the same value,
> an empty list:
>
>      >>> a = []
>      >>> b = []
>      >>> a == b
>      True
>
> 2) In Python, "value" means, what object does a name refer to, or what
> object did an evaluation produce.  We could use "referent" as a
> synonym for this meaning.  The Python operator "is" tests whether two
> values are the same referent, or, the same object. In this sense, "[]"
> always evaluates to a different value, because you get a new empty list
> each time:
>
>      >>> a = []
>      >>> b = []
>      >>> a is b
>      False

And [] is [] gives False too!

For my own benefit, I use the term Handle when shared values are involved.

It comes from the use of file handles (what you get in some languages 
when you open or create a file) which everyone can understand:

* If you copy handle F to G like in an assignment, it obviously doesn't 
copy the contents of the file, just the handle.

* If I compare the contents of files F and H, they might be the same, 
but they are not necessarily the same file.

* If F and G are the same handle, then if I update a file via F, I will 
see the same change via handle G.

The main difference is that when F and G go out of scope and the handles 
disappear, the file hopefully still exists! (And ideally the file is 
first closed via one of the handles.)

 From your example, the syntax '[]' is roughly equivalent to 
'create_empty_file()' in my analogy.

(I don't really want to get back to default arguments, but that would 
extend to:

   def fn(a = create_empty_file()):

which makes it easier to appreciate the implications of 'early' and 
'late' binding. But I still think that reads as though you get a fresh, 
empty file each time.)

-- 
Bartc

-- 
bartc





From ned at nedbatchelder.com  Tue Nov 24 09:50:33 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 06:50:33 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.121.1448375661.2291.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
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 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <mailman.121.1448375661.2291.python-list@python.org>
Message-ID: <894f488e-9707-4184-a53f-670a16399665@googlegroups.com>

On Tuesday, November 24, 2015 at 9:34:36 AM UTC-5, Antoon Pardon wrote:
> Op 20-11-15 om 13:12 schreef Ned Batchelder:
> > On Friday, November 20, 2015 at 6:59:54 AM UTC-5, BartC wrote:
> >> On 20/11/2015 01:05, Steven D'Aprano wrote:
> >>> On Fri, 20 Nov 2015 04:30 am, BartC wrote:
> >>>
> >>>> On 19/11/2015 16:01, Steven D'Aprano wrote:
> >>> [...]
> >>>
> >>>> The whole concept of 'mutable' default is alien to me. A default is just
> >>>> a convenient device to avoid having to write:
> >>>>
> >>>>     fn(0) or fn("") or fn([])
> >>>
> >>> Says who?
> >>
> >> People who want to avoid having to write:
> >>
> >>       fn(0) or fn("") or fn([])
> > 
> > I think we all understand by now that you are unhappy with what happens
> > in Python with mutable defaults.  We get it.  You are not alone. Lots of
> > people are surprised by this.  But it is how Python works.
> 
> May be you should get this message through to the python tribe, so that
> they stop reacting as a stung horse each time someone finds something
> bizarre with the language.

I agree with you: Python experts shouldn't be surprised when people are
surprised by this behavior.

> 
> > I'm not sure what your goal is at this point.  Are you:
> > 
> >   1) still unsure what the behavior is, or 
> >   2) trying to understand why it behaves that way, or
> >   3) hoping to change Python, or
> >   4) trying to convince us that your language is better, or
> >   5) something else?
> 
> Maybe just have us recognize that some aspects of python indeed are bizarre.
> That there is nothing wrong with him thinking so. After that he will have
> to make up his mind whether this bizarre aspect is to big a hurdle for
> using the language or not, because it seems unlikely to change.

I also agree with you: there is nothing wrong with people thinking parts of
Python are bizarre.  What we ask is that people then try to understand
how Python works.  If people say, "This surprised me, Python is stupid!"
and then leave it there, the conversation is bound to go poorly.

Every language works differently, and every language has things that will
surprise new learners.

--Ned.


From rosuav at gmail.com  Tue Nov 24 09:54:45 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 01:54:45 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n31suk$hi5$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <n31suk$hi5$1@dont-email.me>
Message-ID: <CAPTjJmq8mm01pd1nMdXxA43v7RaRebD4FHfDmMfffCd234spuA@mail.gmail.com>

On Wed, Nov 25, 2015 at 1:43 AM, BartC <bc at freeuk.com> wrote:
> It comes from the use of file handles (what you get in some languages when
> you open or create a file) which everyone can understand:
>
> * If you copy handle F to G like in an assignment, it obviously doesn't copy
> the contents of the file, just the handle.
>
> * If I compare the contents of files F and H, they might be the same, but
> they are not necessarily the same file.
>
> * If F and G are the same handle, then if I update a file via F, I will see
> the same change via handle G.
>
> The main difference is that when F and G go out of scope and the handles
> disappear, the file hopefully still exists! (And ideally the file is first
> closed via one of the handles.)

I would recommend picking a different example, actually. An open file
(the resource) is different from the file that actually exists on the
disk. You can open a file for reading three times, and barring access
conflicts etc, you'll get three distinct open-file-objects (file
handles, etc), with separate read pointers, and advancing the file
pointer of one has no effect on the other two. Plus there are other
considerations like the notion of duplicating file handles,
force-duplicating file handles (sometimes called "dup2"), files that
no longer exist on disk but only in memory, files that exist on disk
but no longer have any file names, and so on. Files are way WAY more
complicated than you want to dig into here.

ChrisA


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 09:58:12 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 15:58:12 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <56531ba1$0$1597$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
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 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
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 <56531ba1$0$1597$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <56547B04.1020006@rece.vub.ac.be>

Op 23-11-15 om 14:58 schreef Steven D'Aprano:
> On Mon, 23 Nov 2015 09:40 pm, BartC wrote:
> 
>> On 23/11/2015 07:47, Steven D'Aprano wrote:
>>
>>> I think it would be cleaner and better if Python had dedicated syntax for
>>> declaring static local variables:
>>
>> Interesting. So why is it that when /I/ said:
>>
>>  > On Mon, 23 Nov 2015 12:21 am, BartC wrote:
>>  >
>>  >> But if it's used for static storage, then why not just use static
>>  >> storage?
>>
>> You replied with the insulting:
>>
>>  > /head-desk
>>
>> ?
>>
>> Maybe it's my turn to bang my head on the desk.
> 
> Let me steal^W borrow an idea from Galileo, and present the explanation in
> the form of a dialogue between two philosophers of computer science,
> Salviati and Simplicio, and a third, intelligent layman, Sagredo.
> 
> https://en.wikipedia.org/wiki/Dialogue_Concerning_the_Two_Chief_World_Systems
> 
> 
> Salviati: Function defaults can also be used for static storage.
> 
> Simplicio: If you want static storage, why not use static storage?
> 
> Salviati: Function defaults in Python *are* static storage.
> 
>     Although they not the only way to get static storage, as closures can
> also be used for that purpose, they are surely the simplest way to get
> static storage in Python.
> 
> Sagredo: Simplest though it might be, surely a reasonable person would
> consider that using function parameters for static storage is abuse of the
> feature and a global variable would be better?
> 
> Salviati: Global variables have serious disadvantages. I will agree that
> using function parameters for static storage is something of a code smell,
> but good enough for rough and ready code. Nevertheless, it would be good if
> Python had dedicated syntax for static storage.
> 
> Simplicio: Ah-ha! Gotcha!
> 
> Salviati: No, perhaps you missed that I was referring to a hypothetical
> future addition to Python, not a current feature. But even if it did exist
> today, your statement misses the point that by using function defaults I
> *am* using static storage. In effect, you are telling me that rather than
> using static storage I should instead use static storage.

If you really want mutable static storage, you can simulate it more cleanly with
a closure than using a default argument.

def factory():

  static_dict = {}

  def myfunc(a, b):
    mutate static_dict as much as you like

  return myfunc

myfunc = factory()

Or you can use a class of course.


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 10:01:34 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 16:01:34 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
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 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
Message-ID: <56547BCE.3090502@rece.vub.ac.be>

Op 24-11-15 om 15:34 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>>> Start thinking of it as a constructor call rather than a literal, and
>>> you'll get past most of the confusion.
>>
>> That doesn't change the fact it does look like a literal and not like
>> a constructor.
> 
> Then explain how this is a literal:
> 
> squares = [x*x for x in range(int(input("How far? ")))]
> 
> Or even a simple example like this:
> 
> coords = (randrange(10), randrange(10))
> 
> Neither of them is a literal, even though one of them isn't even
> constructing a list. Tuples may be constant, but they still don't have
> a literal form. (Constant folding can make them function the same way
> literals do, though. If a tuple is constructed of nothing but
> immutable constants - including an empty tuple - then CPython will
> generally create a constant for the whole tuple and use that, rather
> than manually constructing one every time. But the same is true of
> other expressions involving nothing but constants.)
> 
> So if it (in your opinion) looks like a literal but isn't one, whose
> fault is it? Yours or the language's? Not a rhetorical question.
> 
> ChrisA
> 



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 10:03:47 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 16:03:47 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
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 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
Message-ID: <56547C53.8030407@rece.vub.ac.be>

Op 24-11-15 om 15:34 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>>> Start thinking of it as a constructor call rather than a literal, and
>>> you'll get past most of the confusion.
>>
>> That doesn't change the fact it does look like a literal and not like
>> a constructor.
> 
> Then explain how this is a literal:
> 
> squares = [x*x for x in range(int(input("How far? ")))]

So are you saying

  () isn't a literal

because

  (x * x for x in range(int(input("How far? ")))) isn't a literal?

-- 
Antoon.


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 10:10:27 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 16:10:27 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
Message-ID: <56547DE3.1040009@rece.vub.ac.be>

Op 24-11-15 om 15:18 schreef Ned Batchelder:

> 2) In Python, "value" means, what object does a name refer to, or what
> object did an evaluation produce.

I don't think this is correct because that would imply that objects don't
change values (since the value would be the object).

When a list is mutated, it's value has changed. That is how the word is
generally used in python.

-- 
Antoon.



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 10:12:18 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 16:12:18 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
Message-ID: <56547E52.7040107@rece.vub.ac.be>

Op 24-11-15 om 15:34 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>>> Start thinking of it as a constructor call rather than a literal, and
>>> you'll get past most of the confusion.
>>
>> That doesn't change the fact it does look like a literal and not like
>> a constructor.
> 
> Then explain how this is a literal:
> 
> squares = [x*x for x in range(int(input("How far? ")))]

Are you arguing that () isn't a literal because the following
is not a literal?

squares = (x*x for x in range(int(input("How far? "))))

-- 
Antoon.


From rosuav at gmail.com  Tue Nov 24 10:17:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 02:17:14 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <56547C53.8030407@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
Message-ID: <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>

On Wed, Nov 25, 2015 at 2:03 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 24-11-15 om 15:34 schreef Chris Angelico:
>> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>>> Start thinking of it as a constructor call rather than a literal, and
>>>> you'll get past most of the confusion.
>>>
>>> That doesn't change the fact it does look like a literal and not like
>>> a constructor.
>>
>> Then explain how this is a literal:
>>
>> squares = [x*x for x in range(int(input("How far? ")))]
>
> So are you saying
>
>   () isn't a literal
>
> because
>
>   (x * x for x in range(int(input("How far? ")))) isn't a literal?

I'm pretty sure tuple/list/dict display predates comprehensions, and
was already not a literal syntax. Steven, you know the history better
than I do - confirm or deny?

ChrisA


From ned at nedbatchelder.com  Tue Nov 24 10:27:37 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 07:27:37 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.3.1448377833.20593.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <mailman.3.1448377833.20593.python-list@python.org>
Message-ID: <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>

On Tuesday, November 24, 2015 at 10:10:51 AM UTC-5, Antoon Pardon wrote:
> Op 24-11-15 om 15:18 schreef Ned Batchelder:
> 
> > 2) In Python, "value" means, what object does a name refer to, or what
> > object did an evaluation produce.
> 
> I don't think this is correct because that would imply that objects don't
> change values (since the value would be the object).

Sorry, I should have been more precise.  Python documentation suffers from
this two-meaning world also.  There are places where "value" is used in
this second sense, perhaps more places than you realize.  I know when I
wrote "Python Names and Values", I meant it in this second sense.

When you think people's claims about values, or understanding of values
are incorrect, take a moment to decipher which of these two meanings they
are likely using, and see if it more sense.

> When a list is mutated, it's value has changed. That is how the word is
> generally used in python.

I don't know about "generally."  It's true that when a list is mutated, it
is the same referent, but now has a different evalue.  That's what it means
to be mutable.

It's also true that the Python docs, being written in English, will use the
"evalue" sense of the word, mixed together with the "referent" sense of the
word.

And yes, this can be confusing.

--Ned.


From glicerinu at gmail.com  Tue Nov 24 10:29:39 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 16:29:39 +0100
Subject: Futex hang when running event loop on a separated thread
Message-ID: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>

Hi,

I have to run the asyncio.loop on a separated thread because the main
thread is running FUSE. Apparently fuse needs to run on the main
thread because it uses signal():

....
File "/usr/local/lib/python3.4/dist-packages/fuse.py", line 390, in __init__
    old_handler = signal(SIGINT, SIG_DFL)
ValueError: signal only works in main thread


Anyway, when I exit the program it appears that i run into a deadlock
with the eventloop thread, strace is stuck with:

....
futex(0x7f7ba0000c10, FUTEX_WAIT_PRIVATE, 0, NULL


I've tried to stop the event loop from the main thread but the
situation is exactly the same :(

loop_container = {}
handler = threading.Thread(target=run_loop, args=(loop_container,))
try:
   handler.start()
   FUSE(fs)
finally:
    loop_container['loop'].stop()
    # handler.join()

Any idea on how I can shutdown the hole thing? I have to manually kill
the program each time :(

-- 
Marc


From israel at eraalaska.net  Tue Nov 24 10:33:03 2015
From: israel at eraalaska.net (israel)
Date: Tue, 24 Nov 2015 06:33:03 -0900
Subject: Bi-directional sub-process communication
In-Reply-To: <20151124052905.GA41045@cskk.homeip.net>
References: <20151124052512.GA51713@cskk.homeip.net>
 <20151124052905.GA41045@cskk.homeip.net>
Message-ID: <d3a0321e890997eac47f9c9430f7d6bc@ravnalaska.net>

On 11/23/2015 20:29, Cameron Simpson wrote:
> On 24Nov2015 16:25, Cameron Simpson <cs at zip.com.au> wrote:
>> Completely untested example code:
>> 
>> class ReturnEvent:
>>   def __init__(self):
>>     self.event = Event()
> 
> With, of course:
> 
>    def wait(self):
>      return self.event.wait()

Of course :-) Ah, the Event() object comes from the threading module. 
That makes sense. This should work perfectly. Thanks so much for taking 
the time to help me out!
---------
Israel Brewster

> 
> Cheers,
> Cameron Simpson <cs at zip.com.au>
> 
> Maintainer's Motto: If we can't fix it, it ain't broke.


From glicerinu at gmail.com  Tue Nov 24 10:46:15 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 16:46:15 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
Message-ID: <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>

On Tue, Nov 24, 2015 at 4:29 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
> Hi,
>
> I have to run the asyncio.loop on a separated thread because the main
> thread is running FUSE. Apparently fuse needs to run on the main
> thread because it uses signal():
>
> ....
> File "/usr/local/lib/python3.4/dist-packages/fuse.py", line 390, in __init__
>     old_handler = signal(SIGINT, SIG_DFL)
> ValueError: signal only works in main thread
>
>
> Anyway, when I exit the program it appears that i run into a deadlock
> with the eventloop thread, strace is stuck with:
>
> ....
> futex(0x7f7ba0000c10, FUTEX_WAIT_PRIVATE, 0, NULL
>
>
> I've tried to stop the event loop from the main thread but the
> situation is exactly the same :(
>
> loop_container = {}
> handler = threading.Thread(target=run_loop, args=(loop_container,))
> try:
>    handler.start()
>    FUSE(fs)
> finally:
>     loop_container['loop'].stop()
>     # handler.join()
>
> Any idea on how I can shutdown the hole thing? I have to manually kill
> the program each time :(


this can be reproduced with the following program:

import asyncio
import threading
import time

def run_loop(loop_container):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    coro = asyncio.start_server(lambda: 1, '0.0.0.0', 8888, loop=loop)
    server = loop.run_until_complete(coro)
    loop_container['loop'] = loop
    loop.run_forever()

if __name__ == '__main__':
    loop_container = {}
    handler = threading.Thread(target=run_loop, args=(loop_container, ))
    handler.start()
    try:
        time.sleep(10000)
    finally:
        loop_container['loop'].stop()


glic3 at XPS13:/tmp$ python3 /tmp/eventtest.py
^CTraceback (most recent call last):
  File "/tmp/eventtest.py", line 22, in <module>
    time.sleep(10000)
KeyboardInterrupt
^CException ignored in: <module 'threading' from
'/usr/lib/python3.4/threading.py'>
Traceback (most recent call last):
  File "/usr/lib/python3.4/threading.py", line 1294, in _shutdown
    t.join()
  File "/usr/lib/python3.4/threading.py", line 1060, in join
    self._wait_for_tstate_lock()
  File "/usr/lib/python3.4/threading.py", line 1076, in _wait_for_tstate_lock
    elif lock.acquire(block, timeout):
KeyboardInterrupt

it is waiting for tstate_lock in the second ^C

-- 
Marc


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 10:46:22 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 16:46:22 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
Message-ID: <5654864E.2070906@rece.vub.ac.be>

Op 24-11-15 om 16:17 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 2:03 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> Op 24-11-15 om 15:34 schreef Chris Angelico:
>>> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
>>> <antoon.pardon at rece.vub.ac.be> wrote:
>>>>> Start thinking of it as a constructor call rather than a literal, and
>>>>> you'll get past most of the confusion.
>>>>
>>>> That doesn't change the fact it does look like a literal and not like
>>>> a constructor.
>>>
>>> Then explain how this is a literal:
>>>
>>> squares = [x*x for x in range(int(input("How far? ")))]
>>
>> So are you saying
>>
>>   () isn't a literal
>>
>> because
>>
>>   (x * x for x in range(int(input("How far? ")))) isn't a literal?
> 
> I'm pretty sure tuple/list/dict display predates comprehensions, and
> was already not a literal syntax. Steven, you know the history better
> than I do - confirm or deny?

What is your point? I say that [] looks like a literal. Because it
sure resembles () which is a literal.

That [] in fact isn't a literal doesn't contradict it looks like
one.

That you can come up with more complicated list expressions that
are more easily recognizable as not being literals is beside the
point because we have generator expressions that look similar to
those list comprehensions and those generator expressions don't
contradict that () is a literal.

-- 
Antoon.



From rosuav at gmail.com  Tue Nov 24 10:48:32 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 02:48:32 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <5654864E.2070906@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
Message-ID: <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>

On Wed, Nov 25, 2015 at 2:46 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> What is your point? I say that [] looks like a literal. Because it
> sure resembles () which is a literal.
>
> That [] in fact isn't a literal doesn't contradict it looks like
> one.
>
> That you can come up with more complicated list expressions that
> are more easily recognizable as not being literals is beside the
> point because we have generator expressions that look similar to
> those list comprehensions and those generator expressions don't
> contradict that () is a literal.

() is not a literal either.

ChrisA


From steve at pearwood.info  Tue Nov 24 11:11:28 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 03:11:28 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
Message-ID: <56548c31$0$1596$c3e8da3$5496439d@news.astraweb.com>

On Tue, 24 Nov 2015 11:57 pm, Marko Rauhamaa wrote:

> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
> 
>> You then switching to talking about objects, just gives the impression
>> that object is a synonym for value.
> 
> It isn't?

No it isn't.

The definition of "object" -- well, I say "the" definition, but the nasty
truth is that there are many different definitions and nobody really agrees
on what an object is -- the definition of "object" is a software entity
with three fundamental attributes or qualities:

- the type of object;

- the value of the object;

- the identity of the object.

If we limit ourselves to Python, that definition works because Python has
been designed to work that way. Other languages may be different, but when
it comes to Python, it is true by definition that all objects have a type,
a value and an identity because that's what Guido did.

The type of the object is the class that it is an instance of:

py> type("hello")
<class 'str'>

The identity of the object is represented by the integer ID returned by the
id() function. But what it represents is the distinct existence of one
object as compared to another. In real life, the identity of *this* sheep
versus *that* sheep, or this instance of a book versus that instance of the
same book.

(Aside: those of a philosophical bent will quickly realise that we don't
really understand what identity *is*. See, for example, the paradox of my
gradfather's axe. And what distinguishes this electron from some other
electron? There's even a theory in physics that *all electrons are in fact
the one electron*, bouncing backwards and forwards in time repeatedly.)

The value of the object depends on its type -- the value of ints differ from
the value of strings, for example.

Immutable objects have a fixed value for their entire lifespan: the object 2
has the same numeric value, namely two, from the moment it is instantiated
to the moment it is garbage collected.

Mutable objects do not have such a fixed value:

py> L = []  # value is the empty list
py> L.append(None)  # value is now a singleton list containing None
py> L[:] = 'cat dog fox'.split()  # value is now a list containing strings
cat, dog, fox.
py> L
['cat', 'dog', 'fox']


It's the same list, the same object, but the value changes.




-- 
Steven



From random832 at fastmail.com  Tue Nov 24 11:28:58 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 24 Nov 2015 16:28:58 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
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Message-ID: <n32389$g1f$1@ger.gmane.org>

On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
><antoon.pardon at rece.vub.ac.be> wrote:
>>> Start thinking of it as a constructor call rather than a literal, and
>>> you'll get past most of the confusion.
>>
>> That doesn't change the fact it does look like a literal and not like
>> a constructor.
>
> Neither of them is a literal, even though one of them isn't even
> constructing a list. Tuples may be constant, but they still don't have
> a literal form.

How do you define "literal form"? I define it as any syntax that
can participate in ast.literal_eval (And I consider [...] to be a
literal form regardless of whether the ... values are literals or
not). I don't think "Start thinking of it as a constructor call
rather than a literal" is helpful, since it just hides one's
confusion about what a literal is.

The Python documentation itself seems to assume that "literal"
should only be used for things that are a single token, though I
have no idea where this thinking comes from.



From rosuav at gmail.com  Tue Nov 24 11:38:05 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 03:38:05 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n32389$g1f$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <CAPTjJmpStjC4YRkC2kM_P87ZK5wPoO5Q6vdK8GQh6q6A_psv+A@mail.gmail.com>

On Wed, Nov 25, 2015 at 3:28 AM, Random832 <random832 at fastmail.com> wrote:
> On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
>> On Wed, Nov 25, 2015 at 1:24 AM, Antoon Pardon
>><antoon.pardon at rece.vub.ac.be> wrote:
>>>> Start thinking of it as a constructor call rather than a literal, and
>>>> you'll get past most of the confusion.
>>>
>>> That doesn't change the fact it does look like a literal and not like
>>> a constructor.
>>
>> Neither of them is a literal, even though one of them isn't even
>> constructing a list. Tuples may be constant, but they still don't have
>> a literal form.
>
> How do you define "literal form"? I define it as any syntax that
> can participate in ast.literal_eval (And I consider [...] to be a
> literal form regardless of whether the ... values are literals or
> not). I don't think "Start thinking of it as a constructor call
> rather than a literal" is helpful, since it just hides one's
> confusion about what a literal is.

https://docs.python.org/3/reference/lexical_analysis.html#literals

ast.literal_eval can handle a number of things which are not literals,
as long as they use nothing but literals combined by a restricted set
of operators. For instance, Python has no complex literals, only
imaginary ones - but:

>>> ast.literal_eval("1+2j")
(1+2j)

And Python certainly doesn't have "expression literals", yet:

>>> ast.literal_eval("[1,1+1,3]")
[1, 2, 3]

Its support for list display equally doesn't make that into a literal.

> The Python documentation itself seems to assume that "literal"
> should only be used for things that are a single token, though I
> have no idea where this thinking comes from.

Probably the grammar. In other words, it's part of the language's very
definition.

ChrisA


From george.trojan at noaa.gov  Tue Nov 24 11:40:23 2015
From: george.trojan at noaa.gov (George Trojan)
Date: Tue, 24 Nov 2015 16:40:23 +0000
Subject: tuples in conditional assignment (Ben Finney)
In-Reply-To: <mailman.849.1448375910.2290.python-list@python.org>
References: <mailman.849.1448375910.2290.python-list@python.org>
Message-ID: <565492F7.5050408@noaa.gov>

Ben Finney writes:
> Ben Finney <ben+python at benfinney.id.au>
> Date:
> 11/24/2015 04:49 AM
>
> To:
> python-list at python.org
>
>
> George Trojan<george.trojan at noaa.gov>  writes:
>
>> The following code has bitten me recently:
>>
>>>>> t=(0,1)
>>>>> x,y=t if t else 8, 9
>>>>> print(x, y)
>> (0, 1) 9
> You can simplify this by taking assignment out of the picture::
>
>      >>> t = (0, 1)
>      >>> t if t else 8, 9
>      ((0, 1), 9)
>
> So that's an ?expression list? containing a comma. The reference for
> expressions tells us::
>
>      An expression list containing at least one comma yields a tuple. The
>      length of the tuple is the number of expressions in the list.
>
>      <URL:https://docs.python.org/3/reference/expressions.html#expression-lists>
>
>> I was assuming that a comma has the highest order of evaluation
> You were? The operator precedence rules don't even mention comma as an
> operator, so why would you assume that?
>
>      <URL:https://docs.python.org/3/reference/expressions.html#operator-precedence>
What threw me  off was the right column in the table stating that 
binding or tuple display has the highest precedence. Somewhere else 
there is a statement that a comma makes a tuple, not the parentheses, so 
the parentheses on the left did not register with me.
>
>> that is the expression 8, 9 should make a tuple. Why this is not the
>> case?
> I'm not sure why it's the case that you assumed that
>
> My practical advice: I don't bother trying to remember the complete
> operator precedence rules. My simplified precedence rules are:
>
> * ?+?, ?-? have the same precedence.
> * ?*?, ?/?, ?//? have the same precedence.
> * For anything else: Use parentheses to explicitly declare the
>    precedence I want.
>
> Related: When an expression has enough clauses that it's not *completely
> obvious* what's going on, break it up by assigning some sub-parts to
> temporary well-chosen descriptive names (not ?t?).
t was just to illustrate my problem, not the actual code. My lesson is 
to use parentheses in all cases, maybe with an exception for an obvious 
y, x = x, y. In my new C code I always write

if (a) {
     f();
}

instead of a valid 2-liner

if (a)
    f();

Too many times I added indented g() call, and since I do more Python 
than C, the error was not glaringly obvious.
>
> -- \ ?It is far better to grasp the universe as it really is than to | 
> `\ persist in delusion, however satisfying and reassuring.? ?Carl | 
> _o__) Sagan | Ben Finney
George


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 11:41:08 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 17:41:08 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <56549324.8020607@rece.vub.ac.be>

Op 24-11-15 om 16:48 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 2:46 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> What is your point? I say that [] looks like a literal. Because it
>> sure resembles () which is a literal.
>>
>> That [] in fact isn't a literal doesn't contradict it looks like
>> one.
>>
>> That you can come up with more complicated list expressions that
>> are more easily recognizable as not being literals is beside the
>> point because we have generator expressions that look similar to
>> those list comprehensions and those generator expressions don't
>> contradict that () is a literal.
> 
> () is not a literal either.

The byte code sure suggests it is.

Take the following code:

import dis

def f():
  i = 42
  t = ()
  l = []

dis.dis(f)

That produces the following:


  4           0 LOAD_CONST               1 (42)
              3 STORE_FAST               0 (i)

  5           6 LOAD_CONST               2 (())
              9 STORE_FAST               1 (t)

  6          12 BUILD_LIST               0
             15 STORE_FAST               2 (l)
             18 LOAD_CONST               0 (None)
             21 RETURN_VALUE

So on what grounds would you argue that () is not a literal.

-- 
Antoon.


From glicerinu at gmail.com  Tue Nov 24 11:43:59 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 17:43:59 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
Message-ID: <CA+DCN_vj7kd4AGxvjEsPbyXWjzvi1JpXHtCkCSMzCn6QeYobvA@mail.gmail.com>

threading supports the 'daemon' option[1], when set to True and the
program is in *foreground* then the event-loop thread dies when
SIGTERM-ed, however, if the program is in the *background* it doesn't
work! still deadlocked :'''(

while I'm not finding a definitive solution I'll be doing a
os.kill(os.getpid(), signal.SIGKILL) inside the finally block.

[1] https://docs.python.org/3.5/library/threading.html#threading.Thread.daemon

On Tue, Nov 24, 2015 at 4:46 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 4:29 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
>> Hi,
>>
>> I have to run the asyncio.loop on a separated thread because the main
>> thread is running FUSE. Apparently fuse needs to run on the main
>> thread because it uses signal():
>>
>> ....
>> File "/usr/local/lib/python3.4/dist-packages/fuse.py", line 390, in __init__
>>     old_handler = signal(SIGINT, SIG_DFL)
>> ValueError: signal only works in main thread
>>
>>
>> Anyway, when I exit the program it appears that i run into a deadlock
>> with the eventloop thread, strace is stuck with:
>>
>> ....
>> futex(0x7f7ba0000c10, FUTEX_WAIT_PRIVATE, 0, NULL
>>
>>
>> I've tried to stop the event loop from the main thread but the
>> situation is exactly the same :(
>>
>> loop_container = {}
>> handler = threading.Thread(target=run_loop, args=(loop_container,))
>> try:
>>    handler.start()
>>    FUSE(fs)
>> finally:
>>     loop_container['loop'].stop()
>>     # handler.join()
>>
>> Any idea on how I can shutdown the hole thing? I have to manually kill
>> the program each time :(
>
>
> this can be reproduced with the following program:
>
> import asyncio
> import threading
> import time
>
> def run_loop(loop_container):
>     loop = asyncio.new_event_loop()
>     asyncio.set_event_loop(loop)
>     coro = asyncio.start_server(lambda: 1, '0.0.0.0', 8888, loop=loop)
>     server = loop.run_until_complete(coro)
>     loop_container['loop'] = loop
>     loop.run_forever()
>
> if __name__ == '__main__':
>     loop_container = {}
>     handler = threading.Thread(target=run_loop, args=(loop_container, ))
>     handler.start()
>     try:
>         time.sleep(10000)
>     finally:
>         loop_container['loop'].stop()
>
>
> glic3 at XPS13:/tmp$ python3 /tmp/eventtest.py
> ^CTraceback (most recent call last):
>   File "/tmp/eventtest.py", line 22, in <module>
>     time.sleep(10000)
> KeyboardInterrupt
> ^CException ignored in: <module 'threading' from
> '/usr/lib/python3.4/threading.py'>
> Traceback (most recent call last):
>   File "/usr/lib/python3.4/threading.py", line 1294, in _shutdown
>     t.join()
>   File "/usr/lib/python3.4/threading.py", line 1060, in join
>     self._wait_for_tstate_lock()
>   File "/usr/lib/python3.4/threading.py", line 1076, in _wait_for_tstate_lock
>     elif lock.acquire(block, timeout):
> KeyboardInterrupt
>
> it is waiting for tstate_lock in the second ^C
>
> --
> Marc



-- 
Marc


From ian.g.kelly at gmail.com  Tue Nov 24 11:56:02 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 09:56:02 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <56549324.8020607@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
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 <n2l3ne$hbp$1@dont-email.me>
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 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
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 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
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Message-ID: <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:41 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 24-11-15 om 16:48 schreef Chris Angelico:
>> () is not a literal either.
>
> The byte code sure suggests it is.
>
> Take the following code:
>
> import dis
>
> def f():
>   i = 42
>   t = ()
>   l = []
>
> dis.dis(f)
>
> That produces the following:
>
>
>   4           0 LOAD_CONST               1 (42)
>               3 STORE_FAST               0 (i)
>
>   5           6 LOAD_CONST               2 (())
>               9 STORE_FAST               1 (t)
>
>   6          12 BUILD_LIST               0
>              15 STORE_FAST               2 (l)
>              18 LOAD_CONST               0 (None)
>              21 RETURN_VALUE

I'm not sure what this is meant to prove. None is clearly an
identifier, not a literal, and it also gets treated as a constant in
the code above.

> So on what grounds would you argue that () is not a literal.

This enumerates exactly what literals are in Python:

https://docs.python.org/3/reference/lexical_analysis.html#literals

I think it's a rather pedantic point, though. How are nuances of the
grammar at all related to user expectations?


From ned at nedbatchelder.com  Tue Nov 24 11:59:21 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 08:59:21 -0800 (PST)
Subject: Returning a result from 3 items in a list
In-Reply-To: <mailman.119.1448375356.2291.python-list@python.org>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <n31qv3$4en$1@dont-email.me>
 <mailman.119.1448375356.2291.python-list@python.org>
Message-ID: <1900b12c-eb55-4fc5-a45f-b134bf8d36db@googlegroups.com>

On Tuesday, November 24, 2015 at 9:29:30 AM UTC-5, Mark Lawrence wrote:
> On 24/11/2015 14:07, Denis McMahon wrote:
> > On Tue, 24 Nov 2015 02:04:56 -0800, Cai Gengyang wrote:
> >
> >> Here's a dictionary with 3 values :
> >>
> >> results = {
> >>    "gengyang": 14,
> >>    "ensheng": 13, "jordan": 12
> >> }
> >>
> >> How do I define a function that takes the last of the 3 items in that
> >> list and returns Jordan's results i.e. (12) ?
> >
> > You open a web browser and google for "python dictionary"
> >
> 
> Ooh steady on old chap, surely you should have fitted the bib, done the 
> spoon feeding and then changed the nappy?  That appears to me the 
> preferred way of doing things nowadays on c.l.py, rather than bluntly 
> telling people not to be so bloody lazy.

Mark and Denis, if you are having a hard time with newcomers to this list,
perhaps you need to find another list to read?

Yes, Cai Gengyang could do more research before asking questions.  But
your response does nothing to improve the situation.  It's just snark
and bile, and does not exemplify the Python community's culture.

> My fellow Pythonistas, ask not what our language can do for you, ask
> what you can do for our language.

What you can do for our language is put a better foot forward.

--Ned.


From oscar.j.benjamin at gmail.com  Tue Nov 24 12:25:05 2015
From: oscar.j.benjamin at gmail.com (Oscar Benjamin)
Date: Tue, 24 Nov 2015 17:25:05 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
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Message-ID: <CAHVvXxS_kxqA7eoBj_+T5+=v+0YRt=C3AfXgV72HDtbFm_wFog@mail.gmail.com>

On 24 November 2015 at 15:27, Ned Batchelder <ned at nedbatchelder.com> wrote:
> On Tuesday, November 24, 2015 at 10:10:51 AM UTC-5, Antoon Pardon wrote:
>> Op 24-11-15 om 15:18 schreef Ned Batchelder:
>>
>> > 2) In Python, "value" means, what object does a name refer to, or what
>> > object did an evaluation produce.
>>
>> I don't think this is correct because that would imply that objects don't
>> change values (since the value would be the object).
>
> Sorry, I should have been more precise.  Python documentation suffers from
> this two-meaning world also.  There are places where "value" is used in
> this second sense, perhaps more places than you realize.  I know when I
> wrote "Python Names and Values", I meant it in this second sense.

Hi Ned, I read your talk on this subject which was linked to further
up in the thread and it is excellent so thanks for that. I forwarded
it to a colleague for inspiration in our own introductory programming
(with Python) teaching unit.

However when I read it and imagined explaining it to our students I
found myself wanting to adjust the terminology. I would not use the
word value in the way that you suggest. Rather I would want to
contrast "names" (or "references"), "objects" and "values". I think
that many things can be expressed more cleanly with these terms and I
think it corresponds more to the way in which I see Python programmers
use these terms.

So I would say that an object has a value. Immutable objects have
unchanging values but the value of mutable objects can change. The
expression "a is b" determines whether or not a and b are bound to the
same object whereas "a == b" determines if the objects bound to a and
b have the same value. To copy an object is to create a new object
having the same value as the copied object. To mutate an object is to
change its value etc.

Earlier in this thread you said:
"""
In Python, a default value expression
for a function argument is evaluated only once, when the function is defined.
That value (in this case, the actual list) is stored with the function. The
expression is not stored, the value of the expression is. That value (the
actual list) is supplied as the value of the argument if no other value is
supplied.  If you modify that value in the function, the value is modified,
and used again at the next function call.
"""
I think that's a good example of where it would be clearer to
distinguish between objects and values, rather than using the word
value for both. In particular what is stored with the function is the
*object* that results from the default value expression. The *value*
of that object may change if it is mutated but it will still be the
same object each time the function is called (without a corresponding
argument being passed).

--
Oscar


From steve at pearwood.info  Tue Nov 24 12:29:52 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 04:29:52 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <mailman.432.1447888928.16136.python-list@python.org>
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 <n2kcdn$lq0$1@dont-email.me>
 <564dc478$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <mailman.109.1448368689.2291.python-list@python.org>
Message-ID: <56549e92$0$1604$c3e8da3$5496439d@news.astraweb.com>

On Tue, 24 Nov 2015 11:38 pm, Antoon Pardon wrote:

> Op 19-11-15 om 13:45 schreef Steven D'Aprano:
[...]
>> I don't mean that it isn't sometimes useful. Of course it is sometimes
>> useful, there's no doubt about that. But why would you expect the
>> language to default to the *slow*, *expensive*, *complicated* behaviour
>> instead of the *fast*, *cheap*, *simple* behaviour?
> 
> I would say because it is better understandable. 

I disagree that it (late-binding) is more understandable. 

Late-binding (or, "late evaluation" for those who prefer that term) is no
easier to understand than early binding. Earlier, I publicly screwed up
reasoning about late binding.

And so did BartC, whose personal language has precisely the late binding
semantics he wants, exactly as he designed it, and yet he was surprised by
its behaviour leading him to (wrongly) conclude that his language was more
dynamic than Python:

Quote:

    "(Python returns 42; so that means my languages are more dynamic than 
    Python? That's hard to believe!)"

See this thread, post from BartC dated Fri, 20 Nov 2015 08:21:24 am.


> The way default value 
> behave now, is just a little less surprising as when the following segment
> of code would print: [1]
> 
> a = []
> a.append(1)
> b = []
> print b

No, it really isn't anything like that at all. If you (generic you, not
specifically you personally) think that it is similar, you've misunderstood
what is going on.

If we want an analogy, this is a good one:

alist = []
for i in range(20):
    alist.append(i)
    print alist


Are you surprised that alist keeps growing? Contrast this to:


for i in range(20):
    alist = []
    alist.append(i)
    print alist


Are you surprised that alist keeps getting re-set to the empty list?


Change the for-loop to a function declaration. If the binding of the list []
happens inside the indented block, it will happen every time the function
is called (just as it happens each time through the loop in the second
example above). If the binding happens outside of the body, it happens
once, not every time.

Folk like BartC want the function default to be re-evaluated every time the
function is called. I'm not blind to the usefulness of it: I write lots of
functions with late-binding semantics too. I just write them like this:

def func(a=None):
    if a is None:
        a = something()


Perhaps as more people start using function annotations, it will become more
obvious that function declarations aren't re-evaluated every single time
you call the function:

def func(a:some_expression=another_expression): ...

*Both* expressions, the annotation and the default, are evaluated once and
once only.


> Let us not forget that the tutorial talks about Default Argument *Values*.
> And also the language reference talks about precomputed *values*. What
> we really get is a precomputed object.

There is a distinction between value and object, but without seeing the
exact wording and context of the tutorial and language reference, I cannot
tell whether they are misleading or not. There's nothing wrong with talking
about default values. You just have to remember that some values can
change.


>> You already have one way to set the argument to a fresh list every time
>> you call the function: put the code you want executed inside the body of
>> the function. There's no need for a *second* way to get the same result.
> 
> Which is beside the point. The point is understandability.

Okay. Suppose for the sake of the argument I agree with you
that "understandability" is the most important factor here.

Then early binding is still the clear winner, because it has simple, easy to
understand semantics:

- the "def" line is executed once, and once only, including all parameter
defaults and annotations;

- the *body* of the function is executed when the function is called, not
the "def" function declaration.

Since the function defaults are part of the declaration, not the body, it is
far more understandable that it is executed once only.



>> But if you want the default value to be evaluated exactly once, and once
>> only, there is no real alternative to early binding. You could use a
>> global variable, of course, but that is no solution -- that's a problem
>> waiting to happen.
> 
> No more than the situation we have now. The situation we have now is a
> problem waiting to happen too. Which is confirmed again and again. You are
> stacking the deck by calling a possible alternative "a problem waiting to
> happen" while ignoring the problems that happen with the current
> situation.

Pardon me, I certainly am not ignoring anything of the sort. I do
acknowledge that the behaviour of mutable defaults can be surprising. I
even admitted that it surprised me. It's often not the behaviour that you
want, so you have to do something slightly different.

The bottom line is that there are good reasons for the way Python works with
function defaults, but they aren't good for everything. Neither is the
alternative. Whichever design Python used, it would inconvenience people at
some time or another.



-- 
Steven



From antoon.pardon at rece.vub.ac.be  Tue Nov 24 12:32:05 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 18:32:05 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <56549F15.40206@rece.vub.ac.be>

Op 24-11-15 om 17:56 schreef Ian Kelly:

> 
>> So on what grounds would you argue that () is not a literal.
> 
> This enumerates exactly what literals are in Python:
> 
> https://docs.python.org/3/reference/lexical_analysis.html#literals
> 
> I think it's a rather pedantic point, though. How are nuances of the
> grammar at all related to user expectations?
> 

I think that enumaration is too limited. The section starts with:

   Literals are notations for constant values of some built-in types.

() satisfies that definition, which is confirmed by the byte code
produced for it.

-- 
Antoon.


From ned at nedbatchelder.com  Tue Nov 24 12:35:48 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 09:35:48 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.18.1448385928.20593.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
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 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <mailman.3.1448377833.20593.python-list@python.org>
 <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>
 <mailman.18.1448385928.20593.python-list@python.org>
Message-ID: <51dc19ec-9ea0-4b37-bd66-6ebdacc83d87@googlegroups.com>

On Tuesday, November 24, 2015 at 12:25:54 PM UTC-5, Oscar Benjamin wrote:
> On 24 November 2015 at 15:27, Ned Batchelder <ned at nedbatchelder.com> wrote:
> > On Tuesday, November 24, 2015 at 10:10:51 AM UTC-5, Antoon Pardon wrote:
> >> Op 24-11-15 om 15:18 schreef Ned Batchelder:
> >>
> >> > 2) In Python, "value" means, what object does a name refer to, or what
> >> > object did an evaluation produce.
> >>
> >> I don't think this is correct because that would imply that objects don't
> >> change values (since the value would be the object).
> >
> > Sorry, I should have been more precise.  Python documentation suffers from
> > this two-meaning world also.  There are places where "value" is used in
> > this second sense, perhaps more places than you realize.  I know when I
> > wrote "Python Names and Values", I meant it in this second sense.
> 
> Hi Ned, I read your talk on this subject which was linked to further
> up in the thread and it is excellent so thanks for that. I forwarded
> it to a colleague for inspiration in our own introductory programming
> (with Python) teaching unit.
> 
> However when I read it and imagined explaining it to our students I
> found myself wanting to adjust the terminology. I would not use the
> word value in the way that you suggest. Rather I would want to
> contrast "names" (or "references"), "objects" and "values". I think
> that many things can be expressed more cleanly with these terms and I
> think it corresponds more to the way in which I see Python programmers
> use these terms.
> 
> So I would say that an object has a value. Immutable objects have
> unchanging values but the value of mutable objects can change. The
> expression "a is b" determines whether or not a and b are bound to the
> same object whereas "a == b" determines if the objects bound to a and
> b have the same value. To copy an object is to create a new object
> having the same value as the copied object. To mutate an object is to
> change its value etc.
> 
> Earlier in this thread you said:
> """
> In Python, a default value expression
> for a function argument is evaluated only once, when the function is defined.
> That value (in this case, the actual list) is stored with the function. The
> expression is not stored, the value of the expression is. That value (the
> actual list) is supplied as the value of the argument if no other value is
> supplied.  If you modify that value in the function, the value is modified,
> and used again at the next function call.
> """
> I think that's a good example of where it would be clearer to
> distinguish between objects and values, rather than using the word
> value for both. In particular what is stored with the function is the
> *object* that results from the default value expression. The *value*
> of that object may change if it is mutated but it will still be the
> same object each time the function is called (without a corresponding
> argument being passed).
> 
> --
> Oscar

Oscar, thanks for the thoughtful comments. I agree that using "object" for
the result of an expression, and for the referent of a name, would go some
ways to clarifying things.

Perhaps the Python world uses "value" less to mean "object" than I am thinking.
But we do talk about "the value of an expression", and "what value does X
have," and so on.

--Ned.


From tjreedy at udel.edu  Tue Nov 24 12:46:36 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Tue, 24 Nov 2015 12:46:36 -0500
Subject: What is a function parameter =[] for?
In-Reply-To: <56547567.2090603@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <56547567.2090603@rece.vub.ac.be>
Message-ID: <n327q8$ud7$1@ger.gmane.org>

On 11/24/2015 9:34 AM, Antoon Pardon wrote:

I agree that the tutorial should talk about default argument objects 
(which have values) instead of conflating 'object' with 'value'.

> Op 20-11-15 om 13:12 schreef Ned Batchelder:

>> I'm not sure what your goal is at this point.  Are you:
>>
>>    1) still unsure what the behavior is, or
>>    2) trying to understand why it behaves that way, or
>>    3) hoping to change Python, or
>>    4) trying to convince us that your language is better, or
>>    5) something else?
>
> Maybe just have us recognize that some aspects of python indeed are bizarre.

The current behavior under discussion is: default argument expressions 
are evaluated once at function creation time to produce default argument 
objects that are bound to the function object.  I do not see this as 
bizarre.

> That there is nothing wrong with him thinking so.

I do recognize that some would prefer that default argument expressions 
be treated differently, that

def f(a=expression): pass

be compiled to operate as the following does now

def f(a=None):
     a = a if a is not None else expression

perhaps with None replaced with a hidden object() instance.

I find the continuing fuss over the choice that was made to be the 
bizarre thing here.

-- 
Terry Jan Reedy



From gordon at panix.com  Tue Nov 24 12:47:17 2015
From: gordon at panix.com (John Gordon)
Date: Tue, 24 Nov 2015 17:47:17 +0000 (UTC)
Subject: Finding scores from a list
References: <277843f7-c898-4378-85ea-841b09a289e3@googlegroups.com>
Message-ID: <n327r4$3v1$1@reader1.panix.com>

In <277843f7-c898-4378-85ea-841b09a289e3 at googlegroups.com> Cai Gengyang <gengyangcai at gmail.com> writes:


> results = [
> {"id": 1, "name": "ensheng", "score": 10},
> {"id": 2, "name": "gengyang", "score": 12},
> {"id": 3, "name": "jordan", "score": 5},
> ]

Okay, this is a list.

> I want to find gengyang's score. This is what I tried :

> >>> print((results["gengyang"])["score"])

> but I got an error message instead :

> Traceback (most recent call last):
>   File "<pyshell#62>", line 1, in <module>
>     print((results["gengyang"])["score"])
> TypeError: list indices must be integers, not str

Lists are indexed by number, not by name.

You want something like this:

    for result in results:
        if result["name"] == "gengyang":
            print result["score"]
            break

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From ian.g.kelly at gmail.com  Tue Nov 24 12:53:44 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 10:53:44 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <56549F15.40206@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
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 <5654864E.2070906@rece.vub.ac.be>
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Message-ID: <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>

On Tue, Nov 24, 2015 at 10:32 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 24-11-15 om 17:56 schreef Ian Kelly:
>
>>
>>> So on what grounds would you argue that () is not a literal.
>>
>> This enumerates exactly what literals are in Python:
>>
>> https://docs.python.org/3/reference/lexical_analysis.html#literals
>>
>> I think it's a rather pedantic point, though. How are nuances of the
>> grammar at all related to user expectations?
>>
>
> I think that enumaration is too limited. The section starts with:
>
>    Literals are notations for constant values of some built-in types.
>
> () satisfies that definition, which is confirmed by the byte code
> produced for it.

Literals are a type of lexical token. All of the literals shown in
that section are, indeed, tokens. Now I would point you to the grammar
specification:

https://docs.python.org/3/reference/grammar.html

And specifically the "atom" rule, which defines both list displays and
list comprehensions (as well as literals) as being atoms.
Specifically, it parses () as the token '(', followed by an optional
yield_expr or testlist_comp, followed by the token ')'. In no way is
that a single token, nor therefore a literal.


From steve at pearwood.info  Tue Nov 24 12:54:03 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 04:54:03 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
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 <n2l3ne$hbp$1@dont-email.me>
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 <mailman.5.1448378237.20593.python-list@python.org>
Message-ID: <5654a43d$0$1622$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 02:17 am, Chris Angelico wrote:

> On Wed, Nov 25, 2015 at 2:03 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:

>> So are you saying
>>
>>   () isn't a literal
>>
>> because
>>
>>   (x * x for x in range(int(input("How far? ")))) isn't a literal?
> 
> I'm pretty sure tuple/list/dict display predates comprehensions, and
> was already not a literal syntax. Steven, you know the history better
> than I do - confirm or deny?


I must admit that I'm often guilty of referring to [a, b, c] as a list
literal, but, no, () and related forms aren't literals[1], and yes,
tuple/list/dict displays predates list comprehensions by a long time.

Here's Python 1.5:

Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat
4.1.2-52)] on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> import dis
>>> code = compile("(1, 2, 3)", "", "eval")
>>> dis.dis(code)
          0 SET_LINENO          0
          3 LOAD_CONST          0 (1)
          6 LOAD_CONST          1 (2)
          9 LOAD_CONST          2 (3)
         12 BUILD_TUPLE         3
         15 RETURN_VALUE


So you can see the tuple actually gets assembled at runtime. Even if the
tuple is empty, the same process occurs:

>>> code = compile("()", "", "eval")
>>> dis.dis(code)
          0 SET_LINENO          0
          3 BUILD_TUPLE         0
          6 RETURN_VALUE



In contrast, using an actual literal (even a big one) loads the literal as a
pre-existing constant:


>>> code = compile("42000009999999999L", "", "eval")
>>> dis.dis(code)
          0 SET_LINENO          0
          3 LOAD_CONST          0 (42000009999999999L)
          6 RETURN_VALUE




[1] Although with recent versions of Python, the peephole optimizer is
clever enough to treat tuples consisting of nothing but literals as if it
were itself a literal. E.g. in Python 3.3:

py> import dis
py> code = compile("(1, 2, 3)", "", "eval")
py> dis.dis(code)
  1           0 LOAD_CONST               3 ((1, 2, 3))
              3 RETURN_VALUE


But that is a recent optimization, and it relies on the facts that tuples
are immutable, and that the items within the tuple are themselves immutable
literals:


py> code = compile("(1, 2, [])", "", "eval")
py> dis.dis(code)
  1           0 LOAD_CONST               0 (1)
              3 LOAD_CONST               1 (2)
              6 BUILD_LIST               0
              9 BUILD_TUPLE              3
             12 RETURN_VALUE



-- 
Steven



From steve at pearwood.info  Tue Nov 24 12:56:17 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 04:56:17 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <565139f0$0$1598$c3e8da3$5496439d@news.astraweb.com>
 <dbf29qFoem0U1@mid.individual.net>
 <5652c4ac$0$1621$c3e8da3$5496439d@news.astraweb.com>
 <n2uqau$mme$1@dont-email.me>
 <56531ba1$0$1597$c3e8da3$5496439d@news.astraweb.com>
 <mailman.0.1448377100.20593.python-list@python.org>
Message-ID: <5654a4c3$0$1622$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 01:58 am, Antoon Pardon wrote:

> Op 23-11-15 om 14:58 schreef Steven D'Aprano:

> > ... closures can also be used for [static storage] ...

> If you really want mutable static storage, you can simulate it more
> cleanly with a closure than using a default argument.

You don't say. Thanks for letting me know what I already pointed out in the
very post you responded to. It's always nice to see that people read my
words with care and attention to detail.



-- 
Steven



From ian.g.kelly at gmail.com  Tue Nov 24 13:04:05 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 11:04:05 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
Message-ID: <CALwzidnGN-NvsP=sS3MLvhW2KzBfK0csokRnrE5U75Ujfnmp0A@mail.gmail.com>

On Tue, Nov 24, 2015 at 10:53 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 10:32 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> Op 24-11-15 om 17:56 schreef Ian Kelly:
>>
>>>
>>>> So on what grounds would you argue that () is not a literal.
>>>
>>> This enumerates exactly what literals are in Python:
>>>
>>> https://docs.python.org/3/reference/lexical_analysis.html#literals
>>>
>>> I think it's a rather pedantic point, though. How are nuances of the
>>> grammar at all related to user expectations?
>>>
>>
>> I think that enumaration is too limited. The section starts with:
>>
>>    Literals are notations for constant values of some built-in types.
>>
>> () satisfies that definition, which is confirmed by the byte code
>> produced for it.
>
> Literals are a type of lexical token. All of the literals shown in
> that section are, indeed, tokens. Now I would point you to the grammar
> specification:
>
> https://docs.python.org/3/reference/grammar.html
>
> And specifically the "atom" rule, which defines both list displays and
> list comprehensions (as well as literals) as being atoms.
> Specifically, it parses () as the token '(', followed by an optional
> yield_expr or testlist_comp, followed by the token ')'. In no way is
> that a single token, nor therefore a literal.

In case reading the grammar doesn't convince, we can also get this
result from playing with the language:

>>> import tokenize
>>> from io import StringIO
>>> list(tokenize.generate_tokens(StringIO('()').readline))
[TokenInfo(type=52 (OP), string='(', start=(1, 0), end=(1, 1),
line='()'), TokenInfo(type=52 (OP), string=')', start=(1, 1), end=(1,
2), line='()'), TokenInfo(type=0 (ENDMARKER), string='', start=(2, 0),
end=(2, 0), line='')]

Two separate tokens of the OP type.

>>> list(tokenize.generate_tokens(StringIO('42').readline))
[TokenInfo(type=2 (NUMBER), string='42', start=(1, 0), end=(1, 2),
line='42'), TokenInfo(type=0 (ENDMARKER), string='', start=(2, 0),
end=(2, 0), line='')]

One token, of a literal type.

>>> list(tokenize.generate_tokens(StringIO('(1,2,3)').readline))
[TokenInfo(type=52 (OP), string='(', start=(1, 0), end=(1, 1),
line='(1,2,3)'), TokenInfo(type=2 (NUMBER), string='1', start=(1, 1),
end=(1, 2), line='(1,2,3)'), TokenInfo(type=52 (OP), string=',',
start=(1, 2), end=(1, 3), line='(1,2,3)'), TokenInfo(type=2 (NUMBER),
string='2', start=(1, 3), end=(1, 4), line='(1,2,3)'),
TokenInfo(type=52 (OP), string=',', start=(1, 4), end=(1, 5),
line='(1,2,3)'), TokenInfo(type=2 (NUMBER), string='3', start=(1, 5),
end=(1, 6), line='(1,2,3)'), TokenInfo(type=52 (OP), string=')',
start=(1, 6), end=(1, 7), line='(1,2,3)'), TokenInfo(type=0
(ENDMARKER), string='', start=(2, 0), end=(2, 0), line='')]

Two tokens for the parentheses, plus three literal tokens for the
ints, plus two more tokens for the separating commas. Definitely not a
literal.

Credit to Steven for using this approach to make a similar point about
literals in a previous thread.


From zachary.ware+pylist at gmail.com  Tue Nov 24 13:11:10 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Tue, 24 Nov 2015 12:11:10 -0600
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
Message-ID: <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:46 AM, Marc Aymerich <glicerinu at gmail.com> wrote:
> if __name__ == '__main__':
>     loop_container = {}
>     handler = threading.Thread(target=run_loop, args=(loop_container, ))
>     handler.start()
>     try:
>         time.sleep(10000)
>     finally:
>         loop_container['loop'].stop()

loop.stop() must be called from the thread running the loop.  You can
do this by doing
`loop_container['loop'].call_soon_threadsafe(loop_container['loop'].stop)`
from the main thread (untested).

Hope this helps,
-- 
Zach


From marko at pacujo.net  Tue Nov 24 13:13:22 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 24 Nov 2015 20:13:22 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <mailman.3.1448377833.20593.python-list@python.org>
 <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>
 <mailman.18.1448385928.20593.python-list@python.org>
 <51dc19ec-9ea0-4b37-bd66-6ebdacc83d87@googlegroups.com>
Message-ID: <877fl78dvh.fsf@elektro.pacujo.net>

Ned Batchelder <ned at nedbatchelder.com>:

> Oscar, thanks for the thoughtful comments. I agree that using "object"
> for the result of an expression, and for the referent of a name, would
> go some ways to clarifying things.
>
> Perhaps the Python world uses "value" less to mean "object" than I am
> thinking. But we do talk about "the value of an expression", and "what
> value does X have," and so on.

There are all kinds of uses (Google: python "value of"):

  "How to get the value of a variable given its name in a string"

  "The value of some objects can change. Objects whose value can change
  are said to be mutable"

  "I'm taking the return value of one function and using it as the
  argument of another function"

  "Don't get confused ? name on the left, value on the right"

  "We can print the current value of the dictionary in the usual way"

  "A return statement ends the execution of the function call and
  "returns" the result, i.e. the value of the expression following the
  return keyword, to the caller"

  "When we ask python what the value of x > 5 is, we get False"

  "To display the value of a variable, you can use a print statement"

  "Get a value of a specified key"


Personally, I don't like the "official" Python usage:

   Objects whose value can change are said to be mutable

I would prefer this wording:

   Objects whose inner state can change are said to be mutable


Marko


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 13:27:16 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 19:27:16 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <n327q8$ud7$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <564e71f6$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n2n1qp$m35$1@dont-email.me>
 <be65d54a-f6dd-4e32-84cf-117e3cad2e37@googlegroups.com>
 <56547567.2090603@rece.vub.ac.be> <n327q8$ud7$1@ger.gmane.org>
Message-ID: <5654AC04.1050501@rece.vub.ac.be>

Op 24-11-15 om 18:46 schreef Terry Reedy:
> On 11/24/2015 9:34 AM, Antoon Pardon wrote:
> 
> I agree that the tutorial should talk about default argument objects (which have values) instead of conflating 'object' with 'value'.
> 
>> Op 20-11-15 om 13:12 schreef Ned Batchelder:
> 
>>> I'm not sure what your goal is at this point.  Are you:
>>>
>>>    1) still unsure what the behavior is, or
>>>    2) trying to understand why it behaves that way, or
>>>    3) hoping to change Python, or
>>>    4) trying to convince us that your language is better, or
>>>    5) something else?
>>
>> Maybe just have us recognize that some aspects of python indeed are bizarre.
> 
> The current behavior under discussion is: default argument expressions are evaluated once at function creation
> time to produce default argument objects that are bound to the function object.  I do not see this as bizarre.

I do. That a default can be mutated so that your default can have different values upon
different calls is IMO bizarre. I understand where it is coming from and I can live with
it, but I still find it bizarre.

>> That there is nothing wrong with him thinking so.
> 
> I do recognize that some would prefer that default argument expressions be treated differently, that
> 
> def f(a=expression): pass
> 
> be compiled to operate as the following does now
> 
> def f(a=None):
>     a = a if a is not None else expression
> 
> perhaps with None replaced with a hidden object() instance.

An other possibility could be compiling as the following

_tmp = expression
def f(a = None):
    a = a if a is not None else _tmp.copy()

> 
> I find the continuing fuss over the choice that was made to be the bizarre thing here.
> 

IMO that comes because the python tribe often enough can't handle differences of
appreciation. So what if BartC finds this behaviour bizarre? Why this need to
correct him of that notion? By absolutly wanting to argue that it is not bizarre
the most likely result was that BartC went on the defensive, while if people
would simply have acknowlegded that he is not the only one that finds that
behaviour bizarre and then focused on explaining what happens, a lot less fuss
would have been generated.

-- 
Antoon Pardon.


From steve at pearwood.info  Tue Nov 24 13:33:23 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 05:33:23 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <mailman.3.1448377833.20593.python-list@python.org>
 <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>
 <mailman.18.1448385928.20593.python-list@python.org>
 <51dc19ec-9ea0-4b37-bd66-6ebdacc83d87@googlegroups.com>
 <877fl78dvh.fsf@elektro.pacujo.net>
Message-ID: <5654ad75$0$1583$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 05:13 am, Marko Rauhamaa wrote:

> Personally, I don't like the "official" Python usage:
> 
> Objects whose value can change are said to be mutable
> 
> I would prefer this wording:
> 
> Objects whose inner state can change are said to be mutable


I see your point, but "inner state" might not be related to the object's
externally visible value.

For example, dicts have an inner state which can vary, even when their value
remains the same:

# using Python 3.3

py> d = {-1: "a", -2: "b"}
py> e = {-2: "b", -1: "a"}
py> d == e
True
py> print(d, e)
{-2: 'b', -1: 'a'} {-1: 'a', -2: 'b'}

The two dicts have the same value, but their inner state is slightly
different, which is why they print in different order.

Likewise for lists:


py> a = []
py> for i in range(100):
...     a.append(1)
...
py> b = [1]*100
py> a == b
True
py> sys.getsizeof(a) == sys.getsizeof(b)
False



-- 
Steven



From glicerinu at gmail.com  Tue Nov 24 13:37:35 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 19:37:35 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
Message-ID: <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>

On Tue, Nov 24, 2015 at 7:11 PM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 9:46 AM, Marc Aymerich <glicerinu at gmail.com> wrote:
>> if __name__ == '__main__':
>>     loop_container = {}
>>     handler = threading.Thread(target=run_loop, args=(loop_container, ))
>>     handler.start()
>>     try:
>>         time.sleep(10000)
>>     finally:
>>         loop_container['loop'].stop()
>
> loop.stop() must be called from the thread running the loop.  You can
> do this by doing
> `loop_container['loop'].call_soon_threadsafe(loop_container['loop'].stop)`
> from the main thread (untested).
>

Hi Zachary,
nice to know about call_soon_threadsafe!

still it appears to work only if the main thread is in the foreground
(as of calling Thread() with deamon=True), I don't get why it behaves
differently :( maybe it is waiting for other stuff, but no idea how to
confirm this with strace of other means.. i always see the same
'futex(0x7f9a70000c10, FUTEX_WAIT_PRIVATE, 0, NULL'

-- 
Marc


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 13:45:11 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 19:45:11 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
Message-ID: <5654B037.6020107@rece.vub.ac.be>

Op 24-11-15 om 18:53 schreef Ian Kelly:
> On Tue, Nov 24, 2015 at 10:32 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> Op 24-11-15 om 17:56 schreef Ian Kelly:
>>
>>>
>>>> So on what grounds would you argue that () is not a literal.
>>>
>>> This enumerates exactly what literals are in Python:
>>>
>>> https://docs.python.org/3/reference/lexical_analysis.html#literals
>>>
>>> I think it's a rather pedantic point, though. How are nuances of the
>>> grammar at all related to user expectations?
>>>
>>
>> I think that enumaration is too limited. The section starts with:
>>
>>    Literals are notations for constant values of some built-in types.
>>
>> () satisfies that definition, which is confirmed by the byte code
>> produced for it.
> 
> Literals are a type of lexical token. All of the literals shown in
> that section are, indeed, tokens. Now I would point you to the grammar
> specification:
> 
> https://docs.python.org/3/reference/grammar.html
> 
> And specifically the "atom" rule, which defines both list displays and
> list comprehensions (as well as literals) as being atoms.
> Specifically, it parses () as the token '(', followed by an optional
> yield_expr or testlist_comp, followed by the token ')'. In no way is
> that a single token, nor therefore a literal.

I think limiting literals to lexical tokens is too limited. Sure we
can define them like that in the context of the python grammar, but
I don't see why we should limit ourselves to such a definition outside
that context.

I see nothing wrong with regarding -42 as a literal while according
to the python grammar it isn't.

There is nothing wrong with the notion that a literal can be a
compounded value.

But no matter what you want to call it. The dis module shows that
-42 is treated in exactly the same way as 42, which is treated
exactly the same way as () or as (5, 8, 13) which is treated
differently from [] or [5, 8, 13].

Whether you want to call it literals or something else, the fact
remains that (3, 5, 8) is treated like -42 by the CPython interpreter
and [3, 5, 8] is not.

-- 
Antoon.



From ned at nedbatchelder.com  Tue Nov 24 13:54:37 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Tue, 24 Nov 2015 10:54:37 -0800 (PST)
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.26.1448390717.20593.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.473.1447955117.16136.python-list@python.org>
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 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <mailman.26.1448390717.20593.python-list@python.org>
Message-ID: <36243614-aaaf-40df-a6b7-5b669cec02e1@googlegroups.com>

On Tuesday, November 24, 2015 at 1:45:34 PM UTC-5, Antoon Pardon wrote:
> Whether you want to call it literals or something else, the fact
> remains that (3, 5, 8) is treated like -42 by the CPython interpreter
> and [3, 5, 8] is not.

Maybe I've lost the original point in all this minutia about what is a
literal and what is not.  Isn't the key point here that some objects
are mutable (lists), and some are not (tuples, ints)?

--Ned.


From random832 at fastmail.com  Tue Nov 24 14:00:40 2015
From: random832 at fastmail.com (Random832)
Date: Tue, 24 Nov 2015 19:00:40 +0000 (UTC)
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
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 <CAPTjJmpStjC4YRkC2kM_P87ZK5wPoO5Q6vdK8GQh6q6A_psv+A@mail.gmail.com>
Message-ID: <n32c4o$2fq$1@ger.gmane.org>

On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
> Probably the grammar. In other words, it's part of the language's very
> definition.

Then the definition is wrong. I think "literal" is a word whose meaning is
generally agreed on, rather than something each language's spec can invent from
whole cloth for itself. It's not a python term, it's a programming term.

And the documentation doesn't even use it consistently; it calls {} a literal.



From ian.g.kelly at gmail.com  Tue Nov 24 14:15:02 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 12:15:02 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <5654B037.6020107@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
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 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
Message-ID: <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>

On Tue, Nov 24, 2015 at 11:45 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> I think limiting literals to lexical tokens is too limited. Sure we
> can define them like that in the context of the python grammar, but
> I don't see why we should limit ourselves to such a definition outside
> that context.
>
> I see nothing wrong with regarding -42 as a literal while according
> to the python grammar it isn't.
>
> There is nothing wrong with the notion that a literal can be a
> compounded value.

I'm somewhat inclined to agree with this. Taking an example from
another language, if you use Javascript you'll hear all the time about
"object literals" or "object literal notation". If you read the
ECMAScript spec, however, you won't find the phrase "object literal"
in there once. It seems that the common usage of "literal" is not the
same as the way it's used in formal writing of language
specifications.

> But no matter what you want to call it. The dis module shows that
> -42 is treated in exactly the same way as 42, which is treated
> exactly the same way as () or as (5, 8, 13) which is treated
> differently from [] or [5, 8, 13].

This is an implementation detail. The compiler would also be free to
compile -42 into byte code as the negation of the constant 42. That 42
is a literal, on the other hand, is part of the language
specification.


From ian.g.kelly at gmail.com  Tue Nov 24 14:15:48 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 12:15:48 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <n32c4o$2fq$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
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 <n32389$g1f$1@ger.gmane.org>
 <CAPTjJmpStjC4YRkC2kM_P87ZK5wPoO5Q6vdK8GQh6q6A_psv+A@mail.gmail.com>
 <n32c4o$2fq$1@ger.gmane.org>
Message-ID: <CALwzidm2Ue8EVoLa=FHC=L6JdFJrHMWNwGoU3wODEUjga3Kt3A@mail.gmail.com>

On Tue, Nov 24, 2015 at 12:00 PM, Random832 <random832 at fastmail.com> wrote:
> On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
>> Probably the grammar. In other words, it's part of the language's very
>> definition.
>
> Then the definition is wrong. I think "literal" is a word whose meaning is
> generally agreed on, rather than something each language's spec can invent from
> whole cloth for itself. It's not a python term, it's a programming term.

The Python language spec uses the word the same way that other
language specs do. Is it the spec's usage that is wrong, or the common
understanding of it?


From marko at pacujo.net  Tue Nov 24 14:17:10 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Tue, 24 Nov 2015 21:17:10 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <mailman.3.1448377833.20593.python-list@python.org>
 <3589d016-f9ba-4217-83ea-4041ac085230@googlegroups.com>
 <mailman.18.1448385928.20593.python-list@python.org>
 <51dc19ec-9ea0-4b37-bd66-6ebdacc83d87@googlegroups.com>
 <877fl78dvh.fsf@elektro.pacujo.net>
 <5654ad75$0$1583$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <8737vv8ax5.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> On Wed, 25 Nov 2015 05:13 am, Marko Rauhamaa wrote:
>> I would prefer this wording:
>> 
>> Objects whose inner state can change are said to be mutable
>
> I see your point, but "inner state" might not be related to the
> object's externally visible value.

The inner state is indeed inaccessible. We cannot determine immutability
by testing, but we *can* determine mutability (if we're lucky).

> For example, dicts have an inner state which can vary, even when their value
> remains the same:
>
> # using Python 3.3
>
> py> d = {-1: "a", -2: "b"}
> py> e = {-2: "b", -1: "a"}
> py> d == e
> True
> py> print(d, e)
> {-2: 'b', -1: 'a'} {-1: 'a', -2: 'b'}
>
> The two dicts have the same value, but their inner state is slightly
> different, which is why they print in different order.

I'd say an object o is mutable (at least) if it has got a method m such
that:

    before = o.m()
    # any intervening code that does not reassign o
    after = o.m()
    before == after
    => False


Marko


From zachary.ware+pylist at gmail.com  Tue Nov 24 14:41:51 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Tue, 24 Nov 2015 13:41:51 -0600
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
 <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
Message-ID: <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>

On Tue, Nov 24, 2015 at 12:37 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
> still it appears to work only if the main thread is in the foreground
> (as of calling Thread() with deamon=True), I don't get why it behaves
> differently :( maybe it is waiting for other stuff, but no idea how to
> confirm this with strace of other means.. i always see the same
> 'futex(0x7f9a70000c10, FUTEX_WAIT_PRIVATE, 0, NULL'

What's your exact version of Python?  asyncio is still evolving
rapidly, and may behave differently between patch releases (say,
between 3.4.1 and 3.4.3).

I have tried out your reproducer with my fix, and I can't provoke a
hang using Python 3.4.3 on either OSX or Ubuntu Trusty.  Can you give
some more specific directions to reproduce?

-- 
Zach


From glicerinu at gmail.com  Tue Nov 24 15:17:02 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 21:17:02 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
 <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
 <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>
Message-ID: <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>

On Tue, Nov 24, 2015 at 8:41 PM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 12:37 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
>> still it appears to work only if the main thread is in the foreground
>> (as of calling Thread() with deamon=True), I don't get why it behaves
>> differently :( maybe it is waiting for other stuff, but no idea how to
>> confirm this with strace of other means.. i always see the same
>> 'futex(0x7f9a70000c10, FUTEX_WAIT_PRIVATE, 0, NULL'
>
> What's your exact version of Python?  asyncio is still evolving
> rapidly, and may behave differently between patch releases (say,
> between 3.4.1 and 3.4.3).
>
> I have tried out your reproducer with my fix, and I can't provoke a
> hang using Python 3.4.3 on either OSX or Ubuntu Trusty.  Can you give
> some more specific directions to reproduce?
>
> --
> Zach
> --
> https://mail.python.org/mailman/listinfo/python-list


Yep, I'm a bit lost about how fuse implements going into background...
so the only way I have to reproduce this so far is by using fuse :(

# pip3 install fusepy
import asyncio
import threading
import time
import os
import sys
from fuse import FUSE, Operations

def run_loop(loop_container):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    coro = asyncio.start_server(lambda: 1, '0.0.0.0', 8888, loop=loop)
    server = loop.run_until_complete(coro)
    loop_container['loop'] = loop
    loop.run_forever()

if __name__ == '__main__':
    mountpoint = sys.argv[1]
    loop_container = {}
    handler = threading.Thread(target=run_loop, args=(loop_container,))
    handler.start()
    try:
        # with foreground=True works
        FUSE(Operations(), mountpoint, foreground=False)
    finally:
        loop_container['loop'].call_soon_threadsafe(loop_container['loop'].stop)


$ mkdir /tmp/7777
$ python3.5 /tmp/eventtest.py /tmp/7777

# Another terminal
$ ps aux | grep python3.5
glic3    19983  0.5  0.1 215540 10772 ?        Ssl  21:05   0:00
python3.5 me.py /tmp/7777
$ sudo strace -p 19983
Process 19983 attached - interrupt to quit
futex(0x7fff42affca0, FUTEX_WAIT_PRIVATE, 0, NULL) = 0

# Here i fire
$ fusermount -u /tmp/7777

tgkill(19983, 19985, SIGRTMIN)          = 0
futex(0x7fff42affc30, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7f9840afc9d0, FUTEX_WAIT, 19984, NULL


I've just tried with python3.5 and the same behavior. The thing is
that with foreground=True it just works.
thank you for your time!

-- 
Marc


From glicerinu at gmail.com  Tue Nov 24 15:22:49 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Tue, 24 Nov 2015 21:22:49 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
 <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
 <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>
 <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>
Message-ID: <CA+DCN_ttYvBM1_8_62JUtm5Oz0DHJUv_dDvixptvsJ3BauQRZQ@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:17 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 8:41 PM, Zachary Ware
> <zachary.ware+pylist at gmail.com> wrote:
>> On Tue, Nov 24, 2015 at 12:37 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
>>> still it appears to work only if the main thread is in the foreground
>>> (as of calling Thread() with deamon=True), I don't get why it behaves
>>> differently :( maybe it is waiting for other stuff, but no idea how to
>>> confirm this with strace of other means.. i always see the same
>>> 'futex(0x7f9a70000c10, FUTEX_WAIT_PRIVATE, 0, NULL'
>>
>> What's your exact version of Python?  asyncio is still evolving
>> rapidly, and may behave differently between patch releases (say,
>> between 3.4.1 and 3.4.3).
>>
>> I have tried out your reproducer with my fix, and I can't provoke a
>> hang using Python 3.4.3 on either OSX or Ubuntu Trusty.  Can you give
>> some more specific directions to reproduce?
>>
>> --
>> Zach
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>
>
> Yep, I'm a bit lost about how fuse implements going into background...
> so the only way I have to reproduce this so far is by using fuse :(
>
> # pip3 install fusepy
> import asyncio
> import threading
> import time
> import os
> import sys
> from fuse import FUSE, Operations
>
> def run_loop(loop_container):
>     loop = asyncio.new_event_loop()
>     asyncio.set_event_loop(loop)
>     coro = asyncio.start_server(lambda: 1, '0.0.0.0', 8888, loop=loop)
>     server = loop.run_until_complete(coro)
>     loop_container['loop'] = loop
>     loop.run_forever()
>
> if __name__ == '__main__':
>     mountpoint = sys.argv[1]
>     loop_container = {}
>     handler = threading.Thread(target=run_loop, args=(loop_container,))
>     handler.start()
>     try:
>         # with foreground=True works
>         FUSE(Operations(), mountpoint, foreground=False)
>     finally:
>         loop_container['loop'].call_soon_threadsafe(loop_container['loop'].stop)
>
>
> $ mkdir /tmp/7777
> $ python3.5 /tmp/eventtest.py /tmp/7777
>
> # Another terminal
> $ ps aux | grep python3.5
> glic3    19983  0.5  0.1 215540 10772 ?        Ssl  21:05   0:00
> python3.5 me.py /tmp/7777
> $ sudo strace -p 19983
> Process 19983 attached - interrupt to quit
> futex(0x7fff42affca0, FUTEX_WAIT_PRIVATE, 0, NULL) = 0
>
> # Here i fire
> $ fusermount -u /tmp/7777
>
> tgkill(19983, 19985, SIGRTMIN)          = 0
> futex(0x7fff42affc30, FUTEX_WAKE_PRIVATE, 1) = 0
> futex(0x7f9840afc9d0, FUTEX_WAIT, 19984, NULL
>
>
> I've just tried with python3.5 and the same behavior. The thing is
> that with foreground=True it just works.
> thank you for your time!


In case this could be of some use:
strace using foreground=True

$ sudo strace -p 20326
Process 20326 attached - interrupt to quit
futex(0x7fffd9b8e5a0, FUTEX_WAIT_PRIVATE, 0, NULL
# Here umount command
) = 0
tgkill(20326, 20334, SIGRTMIN)          = 0
tgkill(20326, 20335, SIGRTMIN)          = 0
futex(0x7fffd9b8e530, FUTEX_WAKE_PRIVATE, 1) = 0
rt_sigaction(SIGHUP, NULL, {0x7fb60d850540, [], SA_RESTORER,
0x7fb61106ccb0}, 8) = 0
rt_sigaction(SIGINT, NULL, {0x7fb60d850540, [], SA_RESTORER,
0x7fb61106ccb0}, 8) = 0
rt_sigaction(SIGTERM, NULL, {0x7fb60d850540, [], SA_RESTORER,
0x7fb61106ccb0}, 8) = 0
rt_sigaction(SIGPIPE, NULL, {SIG_IGN, [], SA_RESTORER, 0x7fb61106ccb0}, 8) = 0
poll([{fd=5, events=0}], 1, 0)          = 1 ([{fd=5, revents=POLLERR}])
close(5)                                = 0
brk(0x126d000)                          = 0x126d000
rt_sigaction(SIGINT, {0x50b380, [], SA_RESTORER, 0x7fb61106ccb0},
{0x7fb60d850540, [], SA_RESTORER, 0x7fb61106ccb0}, 8) = 0
sendto(8, "\0", 1, 0, NULL, 0)          = 1
futex(0x7fb600001740, FUTEX_WAKE_PRIVATE, 1) = 1
futex(0x9d3204, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x9d3200, {FUTEX_OP_SET,
0, FUTEX_OP_CMP_GT, 1}) = 1
futex(0x9d31c0, FUTEX_WAKE_PRIVATE, 1)  = 1
futex(0x7fb600000c10, FUTEX_WAIT_PRIVATE, 0, NULL) = 0
rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7fb61106ccb0},
{0x50b380, [], SA_RESTORER, 0x7fb61106ccb0}, 8) = 0
epoll_ctl(4, EPOLL_CTL_DEL, 7,
{EPOLLWRBAND|EPOLLMSG|EPOLLERR|0xdea9800, {u32=32694,
u64=23586238107778998}}) = 0
close(7)                                = 0
close(8)                                = 0
close(4)                                = 0
getsockname(6, {sa_family=AF_INET, sin_port=htons(8888),
sin_addr=inet_addr("0.0.0.0")}, [16]) = 0
getpeername(6, 0x7fffd9b8dc70, [16])    = -1 ENOTCONN (Transport
endpoint is not connected)
close(6)                                = 0
madvise(0x7fb600033000, 8192, MADV_DONTNEED) = 0
close(3)                                = 0
exit_group(0)                           = ?
Process 20326 detached



-- 
Marc


From c.buhtz at posteo.jp  Tue Nov 24 15:27:07 2015
From: c.buhtz at posteo.jp (c.buhtz at posteo.jp)
Date: Tue, 24 Nov 2015 21:27:07 +0100
Subject: import logging raise NotImplementedError
Message-ID: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>

I using 'logging' for some month.
But today I have strange problem. When importing it it fails.

Python 3.4.3 (default, Oct 14 2015, 20:33:09)
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import logging  
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2222, in
_find_and_load_unlocked File "<frozen importlib._bootstrap>", line
2164, in _find_spec File "<frozen importlib._bootstrap>", line 1940, in
find_spec File "<frozen importlib._bootstrap>", line 1916, in _get_spec
  File "<frozen importlib._bootstrap>", line 1897, in _legacy_get_spec
  File "<frozen importlib._bootstrap>", line 863, in spec_from_loader
  File "<frozen importlib._bootstrap>", line 904, in
spec_from_file_location File
"/usr/local/lib/python3.4/dist-packages/logging-0.4.9.6-py3.4.egg/logging/__init__.py",
line 618 raise NotImplementedError, 'emit must be implemented '\ ^
SyntaxError: invalid syntax

Any idea about it?

I am not sure if there where an update in the background or something
changed.

The current situation make each "logging" using Python application
unable to run.

The problem happens with Python3 because "logging" is in the default
installation. In Python2 it is not installed. I installed it with
   sudo python2 -m pip install logging -U

This works without problems. Importing in Python2 works, too.
-- 
GnuPGP-Key ID 0751A8EC


From antoon.pardon at rece.vub.ac.be  Tue Nov 24 15:54:43 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 21:54:43 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
Message-ID: <5654CE93.8080900@rece.vub.ac.be>

Op 24-11-15 om 20:15 schreef Ian Kelly:

>> But no matter what you want to call it. The dis module shows that
>> -42 is treated in exactly the same way as 42, which is treated
>> exactly the same way as () or as (5, 8, 13) which is treated
>> differently from [] or [5, 8, 13].
> 
> This is an implementation detail. The compiler would also be free to
> compile -42 into byte code as the negation of the constant 42. That 42
> is a literal, on the other hand, is part of the language
> specification.

I think you are picking nits. Sure the byte code could compile -42 into
a byte code for 42 and a negation. Just as it could compile 42 into byte
code for adding 32, 8 and 2.

The point is, that the reverse isn't true. It couldn't compile [5, 8, 13]
into a LOAD_CONST.

-- 
Antoon Pardon


From cs at zip.com.au  Tue Nov 24 16:06:39 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Wed, 25 Nov 2015 08:06:39 +1100
Subject: Bi-directional sub-process communication
In-Reply-To: <d3a0321e890997eac47f9c9430f7d6bc@ravnalaska.net>
References: <d3a0321e890997eac47f9c9430f7d6bc@ravnalaska.net>
Message-ID: <20151124210639.GA80502@cskk.homeip.net>

On 24Nov2015 06:33, israel <israel at eraalaska.net> wrote:
>On 11/23/2015 20:29, Cameron Simpson wrote:
>>On 24Nov2015 16:25, Cameron Simpson <cs at zip.com.au> wrote:
>>>Completely untested example code:
>>>
>>>class ReturnEvent:
>>>  def __init__(self):
>>>    self.event = Event()
>>
>>With, of course:
>>
>>   def wait(self):
>>     return self.event.wait()
>
>Of course :-) Ah, the Event() object comes from the threading module. 
>That makes sense. This should work perfectly. Thanks so much for 
>taking the time to help me out!

Glad to be of service,
Cameron Simpson <cs at zip.com.au>

All the doors in this ship have nice sunny dispositions. It is their pleasure 
to open for you, and their satisfaction to close with the knowledge of a job 
well done.     - Marvin _The Hitchhiker's Guide to the Galaxy_


From bc at freeuk.com  Tue Nov 24 16:14:12 2015
From: bc at freeuk.com (BartC)
Date: Tue, 24 Nov 2015 21:14:12 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <mailman.33.1448398558.20593.python-list@python.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
Message-ID: <n32jqq$k4j$1@dont-email.me>

On 24/11/2015 20:54, Antoon Pardon wrote:
> Op 24-11-15 om 20:15 schreef Ian Kelly:
>
>>> But no matter what you want to call it. The dis module shows that
>>> -42 is treated in exactly the same way as 42, which is treated
>>> exactly the same way as () or as (5, 8, 13) which is treated
>>> differently from [] or [5, 8, 13].
>>
>> This is an implementation detail. The compiler would also be free to
>> compile -42 into byte code as the negation of the constant 42. That 42
>> is a literal, on the other hand, is part of the language
>> specification.
>
> I think you are picking nits. Sure the byte code could compile -42 into
> a byte code for 42 and a negation. Just as it could compile 42 into byte
> code for adding 32, 8 and 2.
>
> The point is, that the reverse isn't true. It couldn't compile [5, 8, 13]
> into a LOAD_CONST.

I think it can, with a couple of extra instructions:

     LOAD_GLOBAL 0 (list)
     LOAD_CONST  1 ((5, 8, 13))
     CALL_FUNCTION

ie. by converting a tuple to a list, but it can also be done with a 
special byte-code. The effect is a that a constant list can be 
constructed without having to evalate each element at runtime, which I 
assume would be less efficient if the list is big enough (perhaps not 
for just 3 elements).

-- 
Bartc





From antoon.pardon at rece.vub.ac.be  Tue Nov 24 16:25:18 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Tue, 24 Nov 2015 22:25:18 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <n32jqq$k4j$1@dont-email.me>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
Message-ID: <5654D5BE.2090801@rece.vub.ac.be>

Op 24-11-15 om 22:14 schreef BartC:
> On 24/11/2015 20:54, Antoon Pardon wrote:
>> Op 24-11-15 om 20:15 schreef Ian Kelly:
>>
>>>> But no matter what you want to call it. The dis module shows that
>>>> -42 is treated in exactly the same way as 42, which is treated
>>>> exactly the same way as () or as (5, 8, 13) which is treated
>>>> differently from [] or [5, 8, 13].
>>>
>>> This is an implementation detail. The compiler would also be free to
>>> compile -42 into byte code as the negation of the constant 42. That 42
>>> is a literal, on the other hand, is part of the language
>>> specification.
>>
>> I think you are picking nits. Sure the byte code could compile -42 into
>> a byte code for 42 and a negation. Just as it could compile 42 into byte
>> code for adding 32, 8 and 2.
>>
>> The point is, that the reverse isn't true. It couldn't compile [5, 8, 13]
>> into a LOAD_CONST.
> 
> I think it can, with a couple of extra instructions:

Sure it can with a couple of extra instructions. With extra instructions
you can always use constants to build a mutable. The point is that a
tuple can just be loaded as a constant without needing something extra.

-- 
Antoon.


From ian.g.kelly at gmail.com  Tue Nov 24 16:33:17 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 14:33:17 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <5654CE93.8080900@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <5654CE93.8080900@rece.vub.ac.be>
Message-ID: <CALwzidn=ZpDNvQX9e83STODnSw9Dvm64YsPOQGXQ+ZGzznsVww@mail.gmail.com>

On Tue, Nov 24, 2015 at 1:54 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 24-11-15 om 20:15 schreef Ian Kelly:
>
>>> But no matter what you want to call it. The dis module shows that
>>> -42 is treated in exactly the same way as 42, which is treated
>>> exactly the same way as () or as (5, 8, 13) which is treated
>>> differently from [] or [5, 8, 13].
>>
>> This is an implementation detail. The compiler would also be free to
>> compile -42 into byte code as the negation of the constant 42. That 42
>> is a literal, on the other hand, is part of the language
>> specification.
>
> I think you are picking nits.

Yes. This entire subtopic about literals is picking nits. :-)


From kisik2010 at live.ru  Tue Nov 24 16:33:34 2015
From: kisik2010 at live.ru (=?utf-8?B?0JrQuNGB0LjQuiDQnNGD0YDRi9GB0LjQug==?=)
Date: Wed, 25 Nov 2015 00:33:34 +0300
Subject: Reading files from .ar / .deb archives
Message-ID: <DUB407-EAS786B02B886DA8D5A3DD549B5060@phx.gbl>

Hello!
I'm new to Python, so I decided to learn it and write simple apt alternative (apt is somewhat broken for me).
But I can't decide - can I read just one file (/DEBIAN/control) from archive without unpacking it, or do I need to unpack? And what module I can use to handle .ar files? (I read in Wikipedia that .deb is just .ar archive with specific structure)

Sincerely, ??
Sent from my Windows Phone

From pavlos.parissis at gmail.com  Tue Nov 24 16:38:22 2015
From: pavlos.parissis at gmail.com (Pavlos Parissis)
Date: Tue, 24 Nov 2015 22:38:22 +0100
Subject: list slice and generators
Message-ID: <5654D8CE.2020105@gmail.com>

Hi,

Do you see any possible dangerous hidden bug in the below code(using
python2.7 and python3.4)?

My goal is to avoid go through the metrics list twice. But, I don't
know if there will be a problem with doing in place replace of list
elements using 2 generators.

# metrics = ['', '0', '10'....]
metrics = [x.metric(name) for x in self._server_per_proc]
metrics[:] = (converter(x) for x in metrics)
metrics[:] = (x for x in metrics if x is not None)

return calculate(name, metrics)


def calculate(name, metrics):
     if not metrics:
        return None

    if name in METRICS_SUM:
        return sum(metrics)
    elif name in METRICS_AVG:
        return int(sum(metrics)/len(metrics))
    else:
        raise ValueError("Unknown type of calculation for {}".format(name))


def converter(value):
    try:
        return int(float(value))
    except ValueError:
        return value.strip() or None
    except TypeError:
        return None


Cheers,
Pavlos

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From ian.g.kelly at gmail.com  Tue Nov 24 16:53:17 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Tue, 24 Nov 2015 14:53:17 -0700
Subject: Bi-directional sub-process communication
In-Reply-To: <20151124052512.GA51713@cskk.homeip.net>
References: <84B23819-6214-4BDA-959D-85CD46431212@ravnalaska.net>
 <20151124052512.GA51713@cskk.homeip.net>
Message-ID: <CALwzidm6Ynqs31+CguAZ7d39tFgVe-QRRFfgGRRm0NQ1B=qbNA@mail.gmail.com>

On Mon, Nov 23, 2015 at 10:25 PM, Cameron Simpson <cs at zip.com.au> wrote:
> Then #3. I would have a common function/method for submitting a request to
> go to the subprocess, and have that method return an Event on which to wait.
> Then caller then just waits for the Event and collects the data. Obviously,
> the method does not just return the Event, but an Event and something to
> receive the return data. I've got a class called a Result for this kind of
> thing; make a small class containing an Event and which will have a .result
> attribute for the return information; the submitting method allocates one of
> these and returns it. The response handler gets the instance (by looking it
> up from the tag), sets the .result attribute and fires the Event. Your
> caller wakes up from waiting on the Event and consults the .result
> attribute.

Your Result sounds suspiciously like a Future. ;-)


From rosuav at gmail.com  Tue Nov 24 17:00:46 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 09:00:46 +1100
Subject: import logging raise NotImplementedError
In-Reply-To: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>
References: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>
Message-ID: <CAPTjJmqVkJg2_8+5idVPhwGXtSy6A8xGtE8=r7Grq8mEDSmWag@mail.gmail.com>

On Wed, Nov 25, 2015 at 7:27 AM,  <c.buhtz at posteo.jp> wrote:
> The problem happens with Python3 because "logging" is in the default
> installation. In Python2 it is not installed. I installed it with
>    sudo python2 -m pip install logging -U
>
> This works without problems. Importing in Python2 works, too.

You appear to have installed it into your Python 3.4's package
directory, so I suspect you didn't just use the command given. But
don't bother installing it in Py2 either - the docs say it's "New in
version 2.3", so unless you're supporting Python 2.2, you shouldn't
need to worry about this.

ChrisA


From cs at zip.com.au  Tue Nov 24 17:07:22 2015
From: cs at zip.com.au (Cameron Simpson)
Date: Wed, 25 Nov 2015 09:07:22 +1100
Subject: Bi-directional sub-process communication
In-Reply-To: <CALwzidm6Ynqs31+CguAZ7d39tFgVe-QRRFfgGRRm0NQ1B=qbNA@mail.gmail.com>
References: <CALwzidm6Ynqs31+CguAZ7d39tFgVe-QRRFfgGRRm0NQ1B=qbNA@mail.gmail.com>
Message-ID: <20151124220722.GA38663@cskk.homeip.net>

On 24Nov2015 14:53, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>On Mon, Nov 23, 2015 at 10:25 PM, Cameron Simpson <cs at zip.com.au> wrote:
>> Then #3. I would have a common function/method for submitting a request to
>> go to the subprocess, and have that method return an Event on which to wait.
>> Then caller then just waits for the Event and collects the data. Obviously,
>> the method does not just return the Event, but an Event and something to
>> receive the return data. I've got a class called a Result for this kind of
>> thing; make a small class containing an Event and which will have a .result
>> attribute for the return information; the submitting method allocates one of
>> these and returns it. The response handler gets the instance (by looking it
>> up from the tag), sets the .result attribute and fires the Event. Your
>> caller wakes up from waiting on the Event and consults the .result
>> attribute.
>
>Your Result sounds suspiciously like a Future. ;-)

Yeah. I already had this stuff when the futures module was released, with some 
additional stuff futures didn't have (eg my dispatch queue is a priority queue, 
which is handy for some kinds of workflows; default dispatch is FIFO).

My commonest use case/instance is a LateFunction, returned from my Later class.  
Use:

  L = Later()
  LF = L.defer(cllable, *a, *kw)
  ...
  result = LF()

When you call a LateFunction you get the function result, blocking if it has 
not yet been run. It also raises if the deferred function raised. It has 
additional methods, but that is the core use: make it look like a function.

You can do other easy things like:

  L.after(LFs, callable, *a, **kw)

to have a function dispatched after the completion of other LateFunctions or:

  with L.ready():
    ... suite ...

to block until the Later has a slot, then run the suite.

My Result and LateFunctions are subclasses of an Asynchron base class, which 
lets you wait for the result to arrive and has the common methods (wait, etc).  
The Result class supports this:

  R = Result()

  # caller, blocks until value received
  value = R.result

  # worker: deliver result
  R.result = func(blah)

This makes thread cooperation far far more friendly.

Cheers,
Cameron Simpson <cs at zip.com.au>

Ride with a llama and you never ride alone.
- Jeff Earls, DoD #0530, <jearls at tekig6.pen.tek.com>


From rosuav at gmail.com  Tue Nov 24 17:09:27 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 09:09:27 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <n32c4o$2fq$1@ger.gmane.org>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <n32389$g1f$1@ger.gmane.org>
 <CAPTjJmpStjC4YRkC2kM_P87ZK5wPoO5Q6vdK8GQh6q6A_psv+A@mail.gmail.com>
 <n32c4o$2fq$1@ger.gmane.org>
Message-ID: <CAPTjJmrqCG-hqFzNWCRgwfY2LvCbWmUsti9RwoKCuhS3z+LoXA@mail.gmail.com>

On Wed, Nov 25, 2015 at 6:00 AM, Random832 <random832 at fastmail.com> wrote:
> On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
>> Probably the grammar. In other words, it's part of the language's very
>> definition.
>
> Then the definition is wrong. I think "literal" is a word whose meaning is
> generally agreed on, rather than something each language's spec can invent from
> whole cloth for itself. It's not a python term, it's a programming term.
>
> And the documentation doesn't even use it consistently; it calls {} a literal.

Can you link to that, please? Maybe there's something that can be
improved. (Or maybe not.)

ChrisA


From steve at pearwood.info  Tue Nov 24 19:34:45 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 11:34:45 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <564dbe6b$0$1610$c3e8da3$5496439d@news.astraweb.com>
 <n2ki4t$aqj$1@dont-email.me>
 <564df258$0$1604$c3e8da3$5496439d@news.astraweb.com>
 <n2l0s3$5l6$1@dont-email.me>
 <mailman.473.1447955117.16136.python-list@python.org>
 <n2l3ne$hbp$1@dont-email.me>
 <mailman.480.1447960748.16136.python-list@python.org>
 <n2leck$urt$1@dont-email.me>
 <mailman.495.1447973754.16136.python-list@python.org>
 <n2lobe$7gs$1@dont-email.me>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <n32389$g1f$1@ger.gmane.org>
 <CAPTjJmpStjC4YRkC2kM_P87ZK5wPoO5Q6vdK8GQh6q6A_psv+A@mail.gmail.com>
 <mailman.27.1448391661.20593.python-list@python.org>
Message-ID: <56550227$0$1585$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 06:00 am, Random832 wrote:

> On 2015-11-24, Chris Angelico <rosuav at gmail.com> wrote:
>> Probably the grammar. In other words, it's part of the language's very
>> definition.
> 
> Then the definition is wrong. I think "literal" is a word whose meaning is
> generally agreed on, rather than something each language's spec can invent
> from whole cloth for itself. It's not a python term, it's a programming
> term.

Well, I don't know about that. According to you, and Ruby, this is a
literal:

[x+1, y+2*x, func(arg), MyClass(a, b)]

http://ruby-doc.org/core-2.1.1/doc/syntax/literals_rdoc.html#label-Arrays

which seems like an abuse of the term to me. How can it be a *literal* when
it contains non-literal expressions which aren't known until runtime?

Although I note that the actual examples of Array literals and Hash literals
in the Ruby docs punt on the issue by only showing expressions that could
be replaced by constants by a peephole optimizer.


Lua refers to *string literals* but *table constructors*:

http://www.lua.org/manual/5.1/manual.html

Apart from strings, the above manual avoids the use of "literal".



> And the documentation doesn't even use it consistently; it calls {} a
> literal.

Citation required.


-- 
Steven



From steve at pearwood.info  Tue Nov 24 19:36:01 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 11:36:01 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
Message-ID: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 08:25 am, Antoon Pardon wrote:

> The point is that a
> tuple can just be loaded as a constant without needing something extra.


How would one load this tuple as a constant?

(myfile.read(), "%.5f" % sin(x or y))


The point is that *in general*, tuple so-called "literals" (what the docs
call displays) cannot be loaded as constants. If, and only if, the tuple
contains nothing but immutable constants e.g.

(1, 2.0, None, "spam")

then a sufficiently smart compiler may be able to treat that specific tuple
as a constant/literal. But that's a special case, and cannot be generalised
to all tuple displays.

All tuple so-called "literals" e.g. (), (1, 2), (x, y, z) etc. are
fundamentally expressions that *may* have to be built at runtime. Hence the
word "literal" is inappropriate.



-- 
Steven



From steve at pearwood.info  Tue Nov 24 19:39:54 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 11:39:54 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
Message-ID: <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 01:18 am, Ned Batchelder wrote:

> In English, "value" means something like, what is this equal to? 
> There isn't another good word to use in place of "value" here.

There are many different meanings for the English noun "value" (Websters
1913 dictionary includes ten), but I think that the only one that is
relevant is:

"Any particular quantitative determination".

although since we're not just talking about numbers even that needs to be
modified to allow qualitative as well as quantitative determination. E.g.
the value of a particular str object is the string "foobarbaz".


> 2) In Python, "value" means, what object does a name refer to, or what
> object did an evaluation produce.

I don't think that is correct.

The Docs clearly say that "value" is an attribute or quality of objects, not
a synonym for "object":

Quote: "Every object has an identity, a type and a value."

https://docs.python.org/2/reference/datamodel.html#objects-values-and-types

If the docs are a bit inconsistent in ensuring that "value" means something
that objects *have* rather than something that objects *are*, that may be
something to fix.



> The confusion over mutable default arguments arises because the
> defaulted argument always gets the same referent, but it might not
> always be the same evalue.


I'm not sure what value [ha, see what I did there?!] there is in inventing
two new words for things that we already have standard terms for.

"Referent" is just a funny way of saying "object", and "evalue" is just a
misspelling of "value".




-- 
Steven



From lac at openend.se  Tue Nov 24 19:55:51 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 25 Nov 2015 01:55:51 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <201511250055.tAP0tpfO005889@fido.openend.se>

In a message of Wed, 25 Nov 2015 11:39:54 +1100, "Steven D'Aprano" writes:
>I'm not sure what value [ha, see what I did there?!] there is in inventing
>two new words for things that we already have standard terms for.

Done correctly, you can get clarity.

>"Referent" is just a funny way of saying "object", and "evalue" is just a
>misspelling of "value".

If I had a time machine, I would go back to early days of Python and
ban the use of the term 'assignment' and 'value' both.  I would insist
that the term 'binding' be used instead, though if you want to use the
verb refer, to be synonymous with bind, well, I think that would work.
(If not, next trip with the time machine, I ban that one as well.)
Then you make it perfectly clear that what are bound are _objects_
not values (or evalues).  The object has an evalue, but it is the
object that is bound.

It is crystal clear than people on this list mean very different
things when they use the term 'value', and every one of them thinks
that Python agrees with them.  Cutting this knot may require a new
word.

Laura



From rosuav at gmail.com  Tue Nov 24 19:56:45 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 11:56:45 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <8601c9af-a7d9-4642-ba1c-8edd1e4c3390@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <CAPTjJmrhHMqcYvHcaQU_Z8Rzo63rH5F8QrNC5O7g4ufanwOKeQ@mail.gmail.com>

On Wed, Nov 25, 2015 at 11:36 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> If, and only if, the tuple
> contains nothing but immutable constants e.g.
>
> (1, 2.0, None, "spam")
>
> then a sufficiently smart compiler may be able to treat that specific tuple
> as a constant/literal. But that's a special case, and cannot be generalised
> to all tuple displays.

In which case it's simply an example of constant-folding. It's the
same as (1+2j) being called up with LOAD_CONST, despite being an
expression. Recent CPythons are even willing to change what data type
something is, to make it a constant:

>>> dis.dis(lambda x: x in ["a","b","c","d","e"])
  1           0 LOAD_FAST                0 (x)
              3 LOAD_CONST               6 (('a', 'b', 'c', 'd', 'e'))
              6 COMPARE_OP               6 (in)
              9 RETURN_VALUE
>>> dis.dis(lambda x: x in {"a","b","c","d","e"})
  1           0 LOAD_FAST                0 (x)
              3 LOAD_CONST               6 (frozenset({'d', 'c', 'a',
'e', 'b'}))
              6 COMPARE_OP               6 (in)
              9 RETURN_VALUE

Lists and sets are definitely not constants. Tuples and frozensets
aren't literals, but they can be constant. This is the optimizer
talking, though, not language semantics.

ChrisA


From g.rodola at gmail.com  Tue Nov 24 20:50:40 2015
From: g.rodola at gmail.com (Giampaolo Rodola')
Date: Wed, 25 Nov 2015 02:50:40 +0100
Subject: ANN: released psutil 3.3.0 with OpenBSD support
Message-ID: <CAFYqXL-R8Smk2htuqgkNjzfsJqf-gUBKEi+fvG7QwQauRa4diA@mail.gmail.com>

Full story here:
http://grodola.blogspot.com/2015/11/openbsd-support-for-psutil.html

-- 
Giampaolo - http://grodola.blogspot.com


From ben+python at benfinney.id.au  Tue Nov 24 21:17:35 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 25 Nov 2015 13:17:35 +1100
Subject: A name refers to an object, an object has a value,
 equality compares values (was: What is a function parameter =[] for?)
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
Message-ID: <85h9kabz5s.fsf_-_@benfinney.id.au>

Laura Creighton <lac at openend.se> writes:

> If I had a time machine, I would go back to early days of Python and
> ban the use of the term 'assignment' and 'value' both. I would insist
> that the term 'binding' be used instead, though if you want to use the
> verb refer, to be synonymous with bind, well, I think that would work.

+1

> (If not, next trip with the time machine, I ban that one as well.)

I've never been able to remember where the keys are kept; I'm sure they
keep being moved by previous drivers.

> It is crystal clear than people on this list mean very different
> things when they use the term 'value', and every one of them thinks
> that Python agrees with them. Cutting this knot may require a new
> word.

Indeed, in the past I used the term ?value? as synonymous (in Python
context) with the term ?object?. I have become convinced through this
discussion that I should no longer use the terms that way.

Instead, an object *has* a value at a point in time; if the object's
value can change, we say the object is mutable.

The syntax for literals describe a value, but the object once created
may change its value.

Typically, ?is? compares object identity; ?==? compares object value.

The concepts are distinct, so I apologise for misleadingly conflating
them in my terminology.

-- 
 \             ?Skepticism is the highest duty and blind faith the one |
  `\               unpardonable sin.? ?Thomas Henry Huxley, _Essays on |
_o__)                                   Controversial Questions_, 1889 |
Ben Finney



From scott at zml.ca  Tue Nov 24 22:45:37 2015
From: scott at zml.ca (Scott Montreuil)
Date: Wed, 25 Nov 2015 03:45:37 +0000
Subject: if else python
Message-ID: <E2C6B9999C5C1F46A15A3FC49B58764D933A82E8@EX-DB2.zoomer.zml.ca>

Hi,

I have an if statement which seems to run both commands and I cannot figure out why. (just learning so I may be missing something obvious) Any ideas?

while True:
        global latit,longt,jlatit,jlongt,mlongt,mlatit
        response = urllib.urlopen(url)
        data = json.loads(response.read())
        latit = data['Data'][0]['Latitude']
        longt = data['Data'][0]['Longitude']
        jlatit = data['Data'][1]['Latitude']
        jlongt = data['Data'][1]['Longitude']
        mlatit = data['Data'][2]['Latitude']
        mlongt = data['Data'][2]['Longitude']
        for i in user1locat:
                if float(i[2]) <= float(latit) <= float(i[3]) and float(i[4]) >= float(longt) >= float(i[5]):
                        newlocation = int(i[1])
                       screen.addstr(7, 40, "%s at %s" %(user1, i[0]))
                        motor1thread = threading.Thread(target=motor1)
                        motor1thread.start()
                        screen.refresh()
                else:
                        screen.addstr(5, 40, "%s is at an unknown location %f %f\n" % (user1, latit, longt))
                        newlocation = 200
                        motor1thread = threading.Thread(target=motor1)
                        motor1thread.start()
                        screen.refresh()
        time.sleep(10)


From a_kot2 at yahoo.com  Tue Nov 24 23:22:54 2015
From: a_kot2 at yahoo.com (ARONA KANAGARATHNA)
Date: Wed, 25 Nov 2015 04:22:54 +0000 (UTC)
Subject: Istalling python
References: <1283946663.9514492.1448425374289.JavaMail.yahoo.ref@mail.yahoo.com>
Message-ID: <1283946663.9514492.1448425374289.JavaMail.yahoo@mail.yahoo.com>

I tried to install this software python 3.4.3 to my pc which run windows Xp 32. i could installed but it doesnot run.it gives this message "python35-32/python.exe isnot a valid win32 app.Please help me to get solved this problem
Thanks
Aruna

From rosuav at gmail.com  Wed Nov 25 01:20:48 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 17:20:48 +1100
Subject: Istalling python
In-Reply-To: <1283946663.9514492.1448425374289.JavaMail.yahoo@mail.yahoo.com>
References: <1283946663.9514492.1448425374289.JavaMail.yahoo.ref@mail.yahoo.com>
 <1283946663.9514492.1448425374289.JavaMail.yahoo@mail.yahoo.com>
Message-ID: <CAPTjJmo2SpB+gqf5xw_mqb-YyHN2B+z7gpUr6bdx5XYZutjiKw@mail.gmail.com>

On Wed, Nov 25, 2015 at 3:22 PM, ARONA KANAGARATHNA via Python-list
<python-list at python.org> wrote:
> I tried to install this software python 3.4.3 to my pc which run windows Xp 32. i could installed but it doesnot run.it gives this message "python35-32/python.exe isnot a valid win32 app.Please help me to get solved this problem

It looks like you actually installed Python 3.5, not 3.4. If you get
3.4 installed successfully, it should work correctly. Better still,
upgrade to Windows 7, 8, or 10, or make the jump to a free operating
system, and start using something that's actually supported; XP is
going to become increasingly problematic as time goes on.

ChrisA


From marko at pacujo.net  Wed Nov 25 01:44:29 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 08:44:29 +0200
Subject: A name refers to an object, an object has a value,
 equality compares values
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.45.1448417879.20593.python-list@python.org>
Message-ID: <87egfe7f3m.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> Indeed, in the past I used the term ?value? as synonymous (in Python
> context) with the term ?object?. I have become convinced through this
> discussion that I should no longer use the terms that way.
>
> [...]
>
> The concepts are distinct, so I apologise for misleadingly conflating
> them in my terminology.

I don't think the meaning of the word "value" can be restricted in that
way. Let's try to "refactor" the examples I had found in the wild:

  "How to get the value of a variable given its name in a string"
  => How to get the object a variable is bound to given the name of the
     variable in a string

  "The value of some objects can change. Objects whose value can change
  are said to be mutable"
  [no change]

  "I'm taking the return value of one function and using it as the
  argument of another function"
  => I'm taking the return object of one function and using it as the
     argument of another function

  "Don't get confused ? name on the left, value on the right"
  => Don't get confused ? name on the left, object on the right

  "We can print the current value of the dictionary in the usual way"
  [no change]

  "A return statement ends the execution of the function call and
  "returns" the result, i.e. the value of the expression following the
  return keyword, to the caller"
  => A return statement ends the execution of the function call and
     "returns" the result, i.e. the resulting object of the expression
     following the return keyword, to the caller

  "When we ask python what the value of x > 5 is, we get False"
  => When we ask python what the resulting object of x > 5 is, we get
     False

  "To display the value of a variable, you can use a print statement"
  => To display the value of the object a variable is bound to, you can
     use a print statement

  "Get a value of a specified key"
  => Get an image object of a specified key

In a word, it's a lost cause.

It is actually somewhat comical how Python documentation tries, but
fails, to maintain terminological orthodoxy:

  A mapping object maps hashable values to arbitrary objects. [...]

  A dictionary?s keys are almost arbitrary values. Values that are not
  hashable, that is, values containing lists, dictionaries or other
  mutable types (that are compared by value rather than by object
  identity) may not be used as keys.

  [...]

  Dictionaries can be created by placing a comma-separated list of
  key: value pairs within braces

  [...]

  The first object of each item becomes a key in the new dictionary, and
  the second object the corresponding value. If a key occurs more than
  once, the last value for that key becomes the corresponding value in
  the new dictionary.

  [...]

  d[key] = value
    Set d[key] to value.

  [...]

  values()
    Return a new view of the dictionary?s values.

  <URL: https://docs.python.org/3/library/stdtypes.html?highlig
  ht=value#mapping-types-dict>


Marko


From ben+python at benfinney.id.au  Wed Nov 25 01:48:55 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Wed, 25 Nov 2015 17:48:55 +1100
Subject: Reading files from .ar / .deb archives
References: <DUB407-EAS786B02B886DA8D5A3DD549B5060@phx.gbl>
Message-ID: <85d1uybmlk.fsf@benfinney.id.au>

????? ??????? <kisik2010 at live.ru> writes:

> Hello!
> I'm new to Python, so I decided to learn it

Congratulations! Python is a fine language to learn, and this is the
place to discuss general Python topics.

You may also want to join the ?tutor? forum
<URL:https://mail.python.org/mailman/listinfo/tutor>, which is
specifically focussed on collaborative mentoring of Python newcomers.

> and write simple apt alternative (apt is somewhat broken for me).
> But I can't decide - can I read just one file (/DEBIAN/control) from
> archive without unpacking it, or do I need to unpack? And what module
> I can use to handle .ar files? (I read in Wikipedia that .deb is just
> .ar archive with specific structure)

You're right. The ?ar? archive format was IIUC chosen by the early
Debian project because it is very simple.

Unfortunately it is not widely supported; there is no standard library
support in Python for ?ar? archives.

You can use the third-party ?python-debian? library for reading Debian
archive files <URL:https://pypi.python.org/pypi/python-debian/>.

-- 
 \     ?I know when I'm going to die, because my birth certificate has |
  `\                               an expiration date.? ?Steven Wright |
_o__)                                                                  |
Ben Finney



From framstag at rus.uni-stuttgart.de  Wed Nov 25 02:02:06 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 25 Nov 2015 07:02:06 +0000 (UTC)
Subject: readline and TAB-completion?
Message-ID: <n33mde$bgg$1@news2.informatik.uni-stuttgart.de>

I need an input function with GNU readline support. So far I have:

    import readline
    readline.parse_and_bind("tab: complete")

    file = raw_input('File to send: ')


Cursor keys are working, but TAB-completion works only in the current
directory. Example:


File to send: [TAB][TAB]
argv.py              error.py             md5b64.py            x.py
Python_Cookbook.pdf  bookmarks            fexit.py             murksigkeiten
_.py                 compile.py           https.py             wcp

File to send: /tmp/[TAB][TAB]
argv.py              error.py             md5b64.py            x.py
Python_Cookbook.pdf  bookmarks            fexit.py             murksigkeiten
_.py                 compile.py           https.py             wcp


Is there a way to make TAB-completion work for other directories, too?

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 03:14:48 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 09:14:48 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <56556DF8.1080407@rece.vub.ac.be>

Op 20-11-15 om 01:33 schreef Steven D'Aprano:
> On Fri, 20 Nov 2015 07:57 am, Marko Rauhamaa wrote:
>
>> Laura Creighton <lac at openend.se>:
>>
>>> My experience says that the people who are confused want lists to
>>> behave like tuples. period. i.e. they don't want lists to be mutable.
>> I think it's simpler than that. When you have:
>>
>>    def f(x=[]):
>>        y = []
>>
>> the first [] is evaluated when "def" is executed, while the latter [] is
>> evaluated whenever "f" is executed. It's easy to be confused.
> It shouldn't be. The function declaration 
>
>     def f(x=[]):
>
> is executed only once. The function body, conveniently indented to make it
> stand out:
>
>         y = []
>
> is executed every time you call the function. 

What exactly is your point? People's confusions don't disappear
because you as an expert have a good understanding of what is
going on and so are no longer confused.

Some aspects in the langauage are easily grasped and other
aspects tend to create confusion. I see nothing wrong with
people trying to point out what the cause of this confusion
could be. You arguing that people shouldn't be confused is
not helping.

-- 
Antoon.



From rosuav at gmail.com  Wed Nov 25 03:27:47 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 19:27:47 +1100
Subject: A name refers to an object, an object has a value, equality
 compares values
In-Reply-To: <87egfe7f3m.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.45.1448417879.20593.python-list@python.org>
 <87egfe7f3m.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmr3ZhD9oS__dLngNb9PCb4rrGYUK33jG02dQMCJ+G+Zzg@mail.gmail.com>

On Wed, Nov 25, 2015 at 5:44 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> I don't think the meaning of the word "value" can be restricted in that
> way. Let's try to "refactor" the examples I had found in the wild:
>
>   "How to get the value of a variable given its name in a string"
>   => How to get the object a variable is bound to given the name of the
>      variable in a string
>
>   "The value of some objects can change. Objects whose value can change
>   are said to be mutable"
>   [no change]

Agree with these.

>   "I'm taking the return value of one function and using it as the
>   argument of another function"
>   => I'm taking the return object of one function and using it as the
>      argument of another function
>
>   "Don't get confused ? name on the left, value on the right"
>   => Don't get confused ? name on the left, object on the right
>
>   "A return statement ends the execution of the function call and
>   "returns" the result, i.e. the value of the expression following the
>   return keyword, to the caller"
>   => A return statement ends the execution of the function call and
>      "returns" the result, i.e. the resulting object of the expression
>      following the return keyword, to the caller
>
>   "When we ask python what the value of x > 5 is, we get False"
>   => When we ask python what the resulting object of x > 5 is, we get
>      False

These are all talking about the value of an expression. Expressions
have values, just as objects do; in Python, evaluation of an
expression results in some object whose value is the value of the
expression. In many cases, the definition of an expression's value has
nothing to do with object identity, only value - for instance, when
you call methods on strings such as lower(), center(), or format(),
they're required to return a string object with a particular value,
but there's no rule about that object's identity. On the CPython that
I tried:

$ python3
Python 3.4.2 (default, Oct  8 2014, 10:45:20)
[GCC 4.9.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> s = "hello world"
>>> s.lower() is s
False
>>> s.center(len(s)) is s
True
>>> s.format() is s
True

A compliant Python would be allowed to return either True or False for
each of these; but if you change the 'is' checks to '==', they have to
all be True, because the given operations don't change the string's
*value* at all. Same with integer arithmetic, string concatenation,
and so on.

>   "To display the value of a variable, you can use a print statement"
>   => To display the value of the object a variable is bound to, you can
>      use a print statement

This one was probably talking to a new programmer. It's often not
worth going into extreme detail early on; being slightly sloppy with
terminology isn't a problem when what you're really saying is just
"use print to find out what your program is doing".

>   "Get a value of a specified key"
>   => Get an image object of a specified key

Another one that's looking at the value of an expression. In this
case, though, the value is defined based on object identity as well as
value, so I suppose you could word this as:

"Get the object referenced by a specified key"

if you wanted to be pedantic. But dictionaries are defined as mapping
keys to values, and the value associated with a key happens to be
represented by some object.

> In a word, it's a lost cause.

Doesn't need to be.

> It is actually somewhat comical how Python documentation tries, but
> fails, to maintain terminological orthodoxy:
>
>   A mapping object maps hashable values to arbitrary objects. [...]
>
>   A dictionary?s keys are almost arbitrary values. Values that are not
>   hashable, that is, values containing lists, dictionaries or other
>   mutable types (that are compared by value rather than by object
>   identity) may not be used as keys.

No, this is strictly correct. A dictionary's keys are defined by
values, not objects. The dict retains references to the objects used,
but it's equality, not identity, that defines the match.

>>> class S(str): pass
...
>>> k1 = S("hello")
>>> k2 = S("hello")
>>> k1 is k2
False
>>> k1 == k2
True
>>> d = {k1: 42}
>>> d[k2]
42

The *value* of the setter key is what the dictionary cares about,
although it does retain the identity of the object:

>>> next(iter(d)) is k1
True

>   Dictionaries can be created by placing a comma-separated list of
>   key: value pairs within braces
>
>   [...]
>
>   The first object of each item becomes a key in the new dictionary, and
>   the second object the corresponding value. If a key occurs more than
>   once, the last value for that key becomes the corresponding value in
>   the new dictionary.
>
>   [...]
>
>   d[key] = value
>     Set d[key] to value.
>
>   [...]
>
>   values()
>     Return a new view of the dictionary?s values.
>
>   <URL: https://docs.python.org/3/library/stdtypes.html?highlig
>   ht=value#mapping-types-dict>

These are all talking about the other sense of "value" - the way
expressions yield values. If you were to build a binary tree in
Python, you'd have a similar concept of the nodes' "values", which
would again be represented by Python objects; but to the tree, they're
values. It's equivocation on the word "value", but I don't know of a
better word for it (I've sometimes used "payload", but that has its
own issues).

ChrisA


From rosuav at gmail.com  Wed Nov 25 03:32:29 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 19:32:29 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <56556DF8.1080407@rece.vub.ac.be>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
Message-ID: <CAPTjJmrMyKnSm_36x9bk4BmGEwddCxsq-i+_eGvkQL_dO7J2dw@mail.gmail.com>

On Wed, Nov 25, 2015 at 7:14 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> What exactly is your point? People's confusions don't disappear
> because you as an expert have a good understanding of what is
> going on and so are no longer confused.
>
> Some aspects in the langauage are easily grasped and other
> aspects tend to create confusion. I see nothing wrong with
> people trying to point out what the cause of this confusion
> could be. You arguing that people shouldn't be confused is
> not helping.

"Oh come on. It's basic arithmetic. You should be able to add 7 and
7... the result's 14!"

"But it's so confusing. Why can't it be 16? It'd be more convenient
for me if it were 16."

"This is just how arithmetic works."

"But it's still confusing!"

At some point, you have to simply accept that this is how the system
works.. or use a different system. (Octal maybe.) If you are
perpetually confused by Python, you need to either learn how Python
works, or use something else.

ChrisA


From c.buhtz at posteo.jp  Wed Nov 25 03:40:18 2015
From: c.buhtz at posteo.jp (c.buhtz at posteo.jp)
Date: Wed, 25 Nov 2015 09:40:18 +0100
Subject: import logging raise NotImplementedError
In-Reply-To: <CAPTjJmqVkJg2_8+5idVPhwGXtSy6A8xGtE8=r7Grq8mEDSmWag@mail.gmail.com>
References: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>
 <CAPTjJmqVkJg2_8+5idVPhwGXtSy6A8xGtE8=r7Grq8mEDSmWag@mail.gmail.com>
Message-ID: <3p5FzJ4R4Yz5vNN@dovecot03.posteo.de>

On 2015-11-25 09:00 Chris Angelico <rosuav at gmail.com> wrote:
> You appear to have installed it into your Python 3.4's package

No really me. I found out who.

I installed "ebscopy" from its GitHub repository with
"sudo pip3 ./setup.py install"
And this (tried to) install(ed) "logging" from PyPi. Don't know why.

I just removed the egg-file in the dist-utils directory. After that
everything works fine.
-- 
GnuPGP-Key ID 0751A8EC


From marko at pacujo.net  Wed Nov 25 03:43:34 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 10:43:34 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
Message-ID: <87lh9mo4eh.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> At some point, you have to simply accept that this is how the system
> works.. or use a different system. (Octal maybe.) If you are
> perpetually confused by Python, you need to either learn how Python
> works, or use something else.

You are mixing two things: protesting and being confused. Protesting
about a fundamental tenet is of no use, but talking about confusion
might help.

One psychological problem I'm seeing in many answers here is that people
seem to want to defend the honor of Python. It's very religion-like. New
potential converts are welcomed with open arms but when they start to
ask awkward questions, they are treated as suppressive persons.


Marko


From rosuav at gmail.com  Wed Nov 25 03:51:48 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Wed, 25 Nov 2015 19:51:48 +1100
Subject: import logging raise NotImplementedError
In-Reply-To: <3p5FzJ4R4Yz5vNN@dovecot03.posteo.de>
References: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>
 <CAPTjJmqVkJg2_8+5idVPhwGXtSy6A8xGtE8=r7Grq8mEDSmWag@mail.gmail.com>
 <3p5FzJ4R4Yz5vNN@dovecot03.posteo.de>
Message-ID: <CAPTjJmoV5ukM0jk5j7Qwf1GWYQs2OdH2A97FkvE3A_a4db0n2A@mail.gmail.com>

On Wed, Nov 25, 2015 at 7:40 PM,  <c.buhtz at posteo.jp> wrote:
> On 2015-11-25 09:00 Chris Angelico <rosuav at gmail.com> wrote:
>> You appear to have installed it into your Python 3.4's package
>
> No really me. I found out who.
>
> I installed "ebscopy" from its GitHub repository with
> "sudo pip3 ./setup.py install"
> And this (tried to) install(ed) "logging" from PyPi. Don't know why.
>
> I just removed the egg-file in the dist-utils directory. After that
> everything works fine.

Ah! That would do it, yes. (Incidentally, 'pip install ebscopy' would
be how I'd do it.)

I think this is something that would merit reporting upstream. Neither
datetime nor logging is needed in any even half-way recent Python;
removing them would prevent your issue, and I doubt it'll cause
problems on any supported version of Python.

ChrisA


From c.buhtz at posteo.jp  Wed Nov 25 04:00:33 2015
From: c.buhtz at posteo.jp (c.buhtz at posteo.jp)
Date: Wed, 25 Nov 2015 10:00:33 +0100
Subject: import logging raise NotImplementedError
In-Reply-To: <CAPTjJmoV5ukM0jk5j7Qwf1GWYQs2OdH2A97FkvE3A_a4db0n2A@mail.gmail.com>
References: <3p4xjG0FzSz5vN9@dovecot03.posteo.de>
 <CAPTjJmqVkJg2_8+5idVPhwGXtSy6A8xGtE8=r7Grq8mEDSmWag@mail.gmail.com>
 <3p5FzJ4R4Yz5vNN@dovecot03.posteo.de>
 <CAPTjJmoV5ukM0jk5j7Qwf1GWYQs2OdH2A97FkvE3A_a4db0n2A@mail.gmail.com>
Message-ID: <3p5GQg36vXz5vNM@dovecot03.posteo.de>

On 2015-11-25 19:51 Chris Angelico <rosuav at gmail.com> wrote:
> Ah! That would do it, yes. (Incidentally, 'pip install ebscopy' would
> be how I'd do it.)

Yes, I did first. But I had some problems with 'ebscopy' so I wanted to
be sure to get the freshes version of it available. ;)
-- 
GnuPGP-Key ID 0751A8EC


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 04:13:26 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 10:13:26 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmrMyKnSm_36x9bk4BmGEwddCxsq-i+_eGvkQL_dO7J2dw@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <CAPTjJmrMyKnSm_36x9bk4BmGEwddCxsq-i+_eGvkQL_dO7J2dw@mail.gmail.com>
Message-ID: <56557BB6.70101@rece.vub.ac.be>

Op 25-11-15 om 09:32 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 7:14 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> What exactly is your point? People's confusions don't disappear
>> because you as an expert have a good understanding of what is
>> going on and so are no longer confused.
>>
>> Some aspects in the langauage are easily grasped and other
>> aspects tend to create confusion. I see nothing wrong with
>> people trying to point out what the cause of this confusion
>> could be. You arguing that people shouldn't be confused is
>> not helping.
> "Oh come on. It's basic arithmetic. You should be able to add 7 and
> 7... the result's 14!"
>
> "But it's so confusing. Why can't it be 16? It'd be more convenient
> for me if it were 16."
>
> "This is just how arithmetic works."
>
> "But it's still confusing!"
>
> At some point, you have to simply accept that this is how the system
> works.. or use a different system. (Octal maybe.) If you are
> perpetually confused by Python, you need to either learn how Python
> works, or use something else.

Those are not the only choices. The third option is that those at
the drawing board of python come to the conclusion that some aspect
of python is needlessly confusing and change the design.

I also find your comparison disingenous. The responses I see often
enough are not simply: this is how python works. They are often
enough something like: How can you find this confusing, you shouldn't.

If the regulars would answer more something like: Yes it can be confusing,
you are not the only one, but let me explain what is going on. and the
other would keep complaining about it being confusing, you would have
a point.

Instead the regulars all too often go on a tangent on how it shouldn't
be confusing or something similar and then they are surprised that
the exchange that follows isn't very fruitful.

-- 
Antoon Pardon



From lac at openend.se  Wed Nov 25 04:22:38 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 25 Nov 2015 10:22:38 +0100
Subject: Istalling python
In-Reply-To: <1283946663.9514492.1448425374289.JavaMail.yahoo@mail.yahoo.com>
References: <1283946663.9514492.1448425374289.JavaMail.yahoo.ref@mail.yahoo.com>
 <1283946663.9514492.1448425374289.JavaMail.yahoo@mail.yahoo.com>
Message-ID: <201511250922.tAP9McEo014435@fido.openend.se>

In a message of Wed, 25 Nov 2015 04:22:54 +0000, ARONA KANAGARATHNA via Python-
list writes:
>I tried to install this software python 3.4.3 to my pc which run windows Xp 32. i could installed but it doesnot run.it gives this message "python35-32/python.exe isnot a valid win32 app.Please help me to get solved this problem
>Thanks
>Aruna

The 'python35-32' part means that what you were trying to do was
install python3.5 not 3.4.3

And that is what did not work.  The reason that it did not work is
that 3.5 does not run on windows xp.  3.4 is the latest version you
can use.  So, you can either change your operating system, and
then get 3.5, or you can find 3.4.3 over here:
https://www.python.org/downloads/release/python-343/
(downloads on the bottom of the page).

Laura


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 04:36:45 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 10:36:45 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <201511250055.tAP0tpfO005889@fido.openend.se>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
Message-ID: <5655812D.6030203@rece.vub.ac.be>

Op 25-11-15 om 01:55 schreef Laura Creighton:
> In a message of Wed, 25 Nov 2015 11:39:54 +1100, "Steven D'Aprano" writes:
>> I'm not sure what value [ha, see what I did there?!] there is in inventing
>> two new words for things that we already have standard terms for.
> Done correctly, you can get clarity.
>
>> "Referent" is just a funny way of saying "object", and "evalue" is just a
>> misspelling of "value".
> If I had a time machine, I would go back to early days of Python and
> ban the use of the term 'assignment' and 'value' both.  I would insist
> that the term 'binding' be used instead, though if you want to use the
> verb refer, to be synonymous with bind, well, I think that would work.
> (If not, next trip with the time machine, I ban that one as well.)
> Then you make it perfectly clear that what are bound are _objects_
> not values (or evalues).  The object has an evalue, but it is the
> object that is bound.

Not far enough back. Since there are older languages with the same
assignment semantics as python, you should at least go so far.
Otherwise you would get the argument why one shouldn't use the
word assignment in python, while other languages use it for the
same kind of thing.

-- 
Antoon.



From __peter__ at web.de  Wed Nov 25 04:44:05 2015
From: __peter__ at web.de (Peter Otten)
Date: Wed, 25 Nov 2015 10:44:05 +0100
Subject: readline and TAB-completion?
References: <n33mde$bgg$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n33vt5$tii$1@ger.gmane.org>

Ulli Horlacher wrote:

> I need an input function with GNU readline support. So far I have:
> 
>     import readline
>     readline.parse_and_bind("tab: complete")
> 
>     file = raw_input('File to send: ')
> 
> 
> Cursor keys are working, but TAB-completion works only in the current
> directory. Example:
> 
> 
> File to send: [TAB][TAB]
> argv.py              error.py             md5b64.py            x.py

[...]

> Is there a way to make TAB-completion work for other directories, too?

Remove "/" from the set of delimiters:

readline.set_completer_delims(
    "".join(c for c in readline.get_completer_delims() if c != "/"))

> murksigkeiten

I wonder what's in there ;)



From antoon.pardon at rece.vub.ac.be  Wed Nov 25 04:56:27 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 10:56:27 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56546985.8060704@rece.vub.ac.be>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <565585CB.7060709@rece.vub.ac.be>

Op 25-11-15 om 01:36 schreef Steven D'Aprano:
> On Wed, 25 Nov 2015 08:25 am, Antoon Pardon wrote:
>
>> The point is that a
>> tuple can just be loaded as a constant without needing something extra.
>
> How would one load this tuple as a constant?
>
> (myfile.read(), "%.5f" % sin(x or y))

Picking nits again. That respons was done in a context fo what I called
literals. Do you expect me to summarize the context in each response?

> The point is that *in general*, tuple so-called "literals" (what the docs
> call displays) cannot be loaded as constants. If, and only if, the tuple
> contains nothing but immutable constants e.g.
>
> (1, 2.0, None, "spam")
>
> then a sufficiently smart compiler may be able to treat that specific tuple
> as a constant/literal. But that's a special case, and cannot be generalised
> to all tuple displays.
>
> All tuple so-called "literals" e.g. (), (1, 2), (x, y, z) etc. are
> fundamentally expressions that *may* have to be built at runtime. Hence the
> word "literal" is inappropriate.

Literals are constants. So (x, y, z) is not a literal. This is what wikipedia
says: 

    In computer science, a literal is a notation for representing a fixed
    value in source code.

Since (x, y, z) is not a fixed value, it is not a literal.

-- 
Antoon.



From __peter__ at web.de  Wed Nov 25 05:07:08 2015
From: __peter__ at web.de (Peter Otten)
Date: Wed, 25 Nov 2015 11:07:08 +0100
Subject: list slice and generators
References: <5654D8CE.2020105@gmail.com>
Message-ID: <n3418c$k41$1@ger.gmane.org>

Pavlos Parissis wrote:

> Hi,
> 
> Do you see any possible dangerous hidden bug in the below code(using
> python2.7 and python3.4)?
> 
> My goal is to avoid go through the metrics list twice. But, I don't
> know if there will be a problem with doing in place replace of list
> elements using 2 generators.
> 
> # metrics = ['', '0', '10'....]
> metrics = [x.metric(name) for x in self._server_per_proc]
> metrics[:] = (converter(x) for x in metrics)
> metrics[:] = (x for x in metrics if x is not None)

Both generators are executed immediately, and the right side is always 
evaluated before the the slice assignment. Try

metrics = (x.metric(name) for x in self._server_per_proc)
metrics = (converter(x) for x in metrics)
metrics = [x for x in metrics if x is not None]

or

metrics = (converter(x.metric(name)) for x in self._server_per_proc)
metrics = [x for x in metrics if x is not None]

to get down to one intermediate list. Avoiding the last one is a bit tricky:

metrics = (converter(x.metric(name)) for x in self._server_per_proc)
metrics = (x for x in metrics if x is not None)
try:
    # if there is at least one item the generator is not empty
    first = next(metrics)
except StopIteration:
    metrics = ()
else:
    # put the first item back in
    metrics = itertools.chain([first], metrics)
    assert metrics

> return calculate(name, metrics)
> 
> 
> def calculate(name, metrics):
>      if not metrics:
>         return None
> 
>     if name in METRICS_SUM:
>         return sum(metrics)
>     elif name in METRICS_AVG:
          # writing a function that calculates the average without
          # materialising the list left as an exercise ;)
          metrics = list(metrics) 
>         return int(sum(metrics)/len(metrics))
>     else:
>         raise ValueError("Unknown type of calculation for
>         {}".format(name))
> 
> 
> def converter(value):
>     try:
>         return int(float(value))
>     except ValueError:
>         return value.strip() or None
>     except TypeError:
>         return None

Disclaimer: all code untested.



From ammammata at tiscalinet.it  Wed Nov 25 05:14:16 2015
From: ammammata at tiscalinet.it (Ammammata)
Date: Wed, 25 Nov 2015 10:14:16 +0000 (UTC)
Subject: installing 3.5
Message-ID: <XnsA55D7254213C3ammammatatiscalineti@46.4.82.189>

hello ng

well, it's about 10 minutes that's stuck at about 40%, installing C Runtime 
Update (KB2999226) on windows 7 64-bit

is it a known issue (I must end the process manually and do something else 
first) or I just have to wait?

-- 
/-\ /\/\ /\/\ /-\ /\/\ /\/\ /-\ T /-\
-=- -=- -=- -=- -=- -=- -=- -=- - -=-
>>>>>  http://www.bb2002.it :)  <<<<<
........... [ al lavoro ] ...........


From gengyangcai at gmail.com  Wed Nov 25 05:26:51 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Wed, 25 Nov 2015 02:26:51 -0800 (PST)
Subject: Returning a result from 3 items in a list
In-Reply-To: <1900b12c-eb55-4fc5-a45f-b134bf8d36db@googlegroups.com>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <n31qv3$4en$1@dont-email.me>
 <mailman.119.1448375356.2291.python-list@python.org>
 <1900b12c-eb55-4fc5-a45f-b134bf8d36db@googlegroups.com>
Message-ID: <b110a0f7-557a-4da7-ba9b-54624fb1b7bc@googlegroups.com>

Programming is indeed tough ... I wish I had picked up this skill much earlier in life.

But true, I will try to research my questions more in depth before posting here. 

My goal eventually is to build a successful YCombinator based web-based startup. 




On Wednesday, November 25, 2015 at 12:59:36 AM UTC+8, Ned Batchelder wrote:
> On Tuesday, November 24, 2015 at 9:29:30 AM UTC-5, Mark Lawrence wrote:
> > On 24/11/2015 14:07, Denis McMahon wrote:
> > > On Tue, 24 Nov 2015 02:04:56 -0800, Cai Gengyang wrote:
> > >
> > >> Here's a dictionary with 3 values :
> > >>
> > >> results = {
> > >>    "gengyang": 14,
> > >>    "ensheng": 13, "jordan": 12
> > >> }
> > >>
> > >> How do I define a function that takes the last of the 3 items in that
> > >> list and returns Jordan's results i.e. (12) ?
> > >
> > > You open a web browser and google for "python dictionary"
> > >
> > 
> > Ooh steady on old chap, surely you should have fitted the bib, done the 
> > spoon feeding and then changed the nappy?  That appears to me the 
> > preferred way of doing things nowadays on c.l.py, rather than bluntly 
> > telling people not to be so bloody lazy.
> 
> Mark and Denis, if you are having a hard time with newcomers to this list,
> perhaps you need to find another list to read?
> 
> Yes, Cai Gengyang could do more research before asking questions.  But
> your response does nothing to improve the situation.  It's just snark
> and bile, and does not exemplify the Python community's culture.
> 
> > My fellow Pythonistas, ask not what our language can do for you, ask
> > what you can do for our language.
> 
> What you can do for our language is put a better foot forward.
> 
> --Ned.



From ammammata at tiscalinet.it  Wed Nov 25 05:27:20 2015
From: ammammata at tiscalinet.it (Ammammata)
Date: Wed, 25 Nov 2015 10:27:20 +0000 (UTC)
Subject: installing 3.5
References: <XnsA55D7254213C3ammammatatiscalineti@46.4.82.189>
Message-ID: <XnsA55D748AB9534ammammatatiscalineti@46.4.82.189>

Il giorno Wed 25 Nov 2015 11:14:16a, *Ammammata* inviava su 
comp.lang.python il messaggio 
news:XnsA55D7254213C3ammammatatiscalineti at 46.4.82.189. Vediamo cosa 
scrisse:

> or I just have to wait?
> 

this one
It took ages to install, time to change my HDD

-- 
/-\ /\/\ /\/\ /-\ /\/\ /\/\ /-\ T /-\
-=- -=- -=- -=- -=- -=- -=- -=- - -=-
>>>>>  http://www.bb2002.it :)  <<<<<
........... [ al lavoro ] ...........


From steve at pearwood.info  Wed Nov 25 05:52:24 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 21:52:24 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
Message-ID: <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 07:14 pm, Antoon Pardon wrote:

> Op 20-11-15 om 01:33 schreef Steven D'Aprano:
>> On Fri, 20 Nov 2015 07:57 am, Marko Rauhamaa wrote:
>>
>>> Laura Creighton <lac at openend.se>:
>>>
>>>> My experience says that the people who are confused want lists to
>>>> behave like tuples. period. i.e. they don't want lists to be mutable.
>>> I think it's simpler than that. When you have:
>>>
>>>    def f(x=[]):
>>>        y = []
>>>
>>> the first [] is evaluated when "def" is executed, while the latter [] is
>>> evaluated whenever "f" is executed. It's easy to be confused.
>> It shouldn't be. The function declaration
>>
>>     def f(x=[]):
>>
>> is executed only once. The function body, conveniently indented to make
>> it stand out:
>>
>>         y = []
>>
>> is executed every time you call the function.
> 
> What exactly is your point? 

That there is a simple analogy between the distinction between code
inside/outside a for-loop, and code inside/outside a function. If you can
understand why this loops forever, instead of just twice, then you can
understand why function defaults work the way they do:

L = [1, 2]
for i in L:
    L.append(i)
    print(L)


There is nothing "bizarre" or complicated or difficult to understand
happening here. It might not be what you want to happen. It might not be
what you expect to happen. But if you can't understand why it happens even
after multiple explanations, then your learning skills are severely
lacking.



> People's confusions don't disappear 
> because you as an expert have a good understanding of what is
> going on and so are no longer confused.

I'm an expert? Awesome!

No. But people's confusion would disappear if they would:

- think about the process
- try to follow the steps of what is happening
- pay attention to the explanations given
- and ask for clarification instead of arguing.

I have come to the conclusion that there is nobody as stupid as an
intelligent person who refuses to learn.

I really don't know how more clear we can possibly be. If you take a list,
initialised as the empty list ONCE, and then modify it repeatedly, the list
doesn't magically become empty just because you want it to be empty.

I completely understand beginners making this mistake:

# Simulate tossing a coin until it is heads.
count = 1
coin = random.choice(['heads', 'tails'])
while coin != 'heads':
    count += 1

"Why does the loop run forever?"


The coin doesn't magically toss itself, no matter how intuitively obvious it
is that it should. (And I'm not making this example up -- I've seen three
or four beginners make equivalent errors. It seems to be a very common
conceptual mistake.)

These beginners, at least, don't argue back that it is "bizarre" and stupid
and crazy that you have to choose a new value for the coin variable each
time through the loop. They soon learn that code outside the loop only runs
once, if you want it to run each time through the loop, you should put it
inside the body of the loop.

Just like functions. If you want code to run each time you call the
function, PUT IT INSIDE THE FUNCTION BODY.


> Some aspects in the langauage are easily grasped and other
> aspects tend to create confusion. 

You're right. Some aspects of the language are inherently confusing and hard
to reason about. Threads are an example of that. The more powerful, and
tricky, aspects of regular expressions. The weird stuff that happens during
interpreter shutdown if you have __del__ methods in your objects. __del__
methods in general. There are many things which are hard to reason about,
and therefore confusing.

*This is not one of them.*

This is not hard to reason about. The rules are no different from what
happens in simple, ordinary code:

L = []  # Initialise the list *once*.
def func():
    L.append(1)
    return L

If I call func() three times, what value does it return? If you can get
that, you can get this:

def func(L=[]):  # Initialise the list *once*.
    L.append(1)
    return L

Confusing? Absolutely not. Or rather, if anyone cannot understand the
behaviour of either function *after having it explained multiple times*,
then programming is the wrong area for them. They should take up something
more suited to their intellectual limitations, like dish washing, ditch
digging, or politics.

But is it predictable or intuitive? No, I agree, this behaviour is not
intuitive, if you are coming from a background without equivalent rules. I
will completely grant you that most people without Python experience would
not correctly predict the behaviour of mutable defaults.

I was caught out on that too, as I already admitted. Even though I already
knew all the facts I needed to predict the behaviour correctly, I didn't
put 2+2 together and get 4. That's *my bad*, not the language's fault.

How much harder must it be for those who don't know the essential facts? I
don't expect anyone to intuit the behaviour of Python defaults. That would
be unreasonable. There's no shame in guessing wrong from a position of
ignorance.

Me, on the other hand... I should have known better. I did know better.

But there's a big difference between those who guess wrong from a position
of ignorance, and then make an honest attempt to understand the behaviour
and why it actually does make sense and is even sometimes useful (even if
they don't like it), and those people who insist that it is nonsensical,
magical and "bizarre".


 

-- 
Steven



From steve at pearwood.info  Wed Nov 25 05:58:09 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Wed, 25 Nov 2015 21:58:09 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <87lh9mo4eh.fsf@elektro.pacujo.net>
Message-ID: <56559443$0$1611$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 07:43 pm, Marko Rauhamaa wrote:

> One psychological problem I'm seeing in many answers here is that people
> seem to want to defend the honor of Python. 

No, your other honour!


(It's an Oglaf reference, and *definitely* not safe for work. I'm not even
going to link to it.)



-- 
Steven



From antoon.pardon at rece.vub.ac.be  Wed Nov 25 06:04:03 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 12:04:03 +0100
Subject: Is there an meaning of '[[]]' in a list?
In-Reply-To: <n2uke1$8qm$1@ger.gmane.org>
References: <750e1071-395b-4e9b-ad64-05faa174a5bf@googlegroups.com>
 <mailman.454.1447933236.16136.python-list@python.org>
 <V9s4y.489754$6i2.102301@fx35.am4> <n2uke1$8qm$1@ger.gmane.org>
Message-ID: <565595A3.2050003@rece.vub.ac.be>

Op 23-11-15 om 09:57 schreef Peter Otten:
> Quivis wrote:
>
>> On Thu, 19 Nov 2015 12:40:17 +0100, Peter Otten wrote:
>>
>>> those questions that are a little harder
>> And just how is he going to determine what is hard?
> Note that I said "a little harder", not "hard".
>
> Write down your next ten or so questions, then work through the tutorial or 
> another introductory text, then use a search engine, then post the one or 
> two questions that are still unanswered.

The problem is of course that he may already be doing that. We have just
no idea about which questions he solved for himself because those are
not mentioned here.

But I do agree that he probably should try harder, he doesn't seem to
come with the result of an experiment he tried where the result surprised
him.

-- 
Antoon.



From PointedEars at web.de  Wed Nov 25 06:10:09 2015
From: PointedEars at web.de (Thomas 'PointedEars' Lahn)
Date: Wed, 25 Nov 2015 11:10:09 +0000
Subject: if else python
References: <mailman.51.1448431821.20593.python-list@python.org>
Message-ID: <1555359.vKlKcyBEKv@PointedEars.de>

Scott Montreuil wrote:

> I have an if statement which seems to run both commands and I cannot
> figure out why. (just learning so I may be missing something obvious) Any
> ideas?

Use a Python IDE and debugger.  I recommend PyDev, but YMMV.

> while True:
>         global latit,longt,jlatit,jlongt,mlongt,mlatit

Why globals?  Why so many?

>         response = urllib.urlopen(url)
>         data = json.loads(response.read())
>         latit = data['Data'][0]['Latitude']
>         longt = data['Data'][0]['Longitude']

DRY.

        [latit, longt] = [data['Data'][0][key]
                          for key in ['Latitude', 'Longitude']]

There may be even more efficient ways.  Certainly the value of data['Data'] 
can be stored in a variable.

>         jlatit = data['Data'][1]['Latitude']
>         jlongt = data['Data'][1]['Longitude']
>         mlatit = data['Data'][2]['Latitude']
>         mlongt = data['Data'][2]['Longitude']

Shouts out for applying DRY.

[added line continuation escape]

>         for i in user1locat:
>                 if float(i[2]) <= float(latit) <= float(i[3]) and \
>                 float(i[4]) >= float(longt) >= float(i[5]):
>                         newlocation = int(i[1])
>                        screen.addstr(7, 40, "%s at %s" %(user1, i[0]))

["{0} at {1}".format(user1, i[0]) is recommended instead:

<https://docs.python.org/3/library/stdtypes.html#old-string-formatting>]

The indentation of the last quoted line is ? as posted ? one space to the 
left of that of the previous line.  That is a syntax error in Python as the 
?if? statement is 8 columns to the left instead.  Perhaps you have mixed 
tabs and spaces and that got lost while posting; in any case, this is not 
the original code, so all bets are off.

Also, 8 spaces per indentation level is too much; it certainly is too much 
to be posted to Usenet where there is a customary limit at the 80th column.
An indentation of 4 spaces per level is recommended for Python code.  If the 
code still extends beyond the 80th column, you should use a line 
continuation escape sequence if that is syntactically necessary (it is not 
in my suggestion above).

<https://www.python.org/dev/peps/pep-0008/#indentation>


-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.


From breamoreboy at yahoo.co.uk  Wed Nov 25 06:22:23 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 25 Nov 2015 11:22:23 +0000
Subject: Returning a result from 3 items in a list
In-Reply-To: <b110a0f7-557a-4da7-ba9b-54624fb1b7bc@googlegroups.com>
References: <133829df-f57f-442f-9dbf-b22b22f656ae@googlegroups.com>
 <n31qv3$4en$1@dont-email.me>
 <mailman.119.1448375356.2291.python-list@python.org>
 <1900b12c-eb55-4fc5-a45f-b134bf8d36db@googlegroups.com>
 <b110a0f7-557a-4da7-ba9b-54624fb1b7bc@googlegroups.com>
Message-ID: <n345lj$6qn$1@ger.gmane.org>

On 25/11/2015 10:26, Cai Gengyang wrote:
> But true, I will try to research my questions more in depth before posting here.
>

Please also research how to intersperse your answers or bottom post.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From harvest at should.be.invalid  Wed Nov 25 06:39:44 2015
From: harvest at should.be.invalid (Jussi Piitulainen)
Date: Wed, 25 Nov 2015 13:39:44 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
Message-ID: <lf5a8q2xq7z.fsf@ling.helsinki.fi>

Antoon Pardon writes:

> Op 25-11-15 om 01:55 schreef Laura Creighton:

>> If I had a time machine, I would go back to early days of Python and
>> ban the use of the term 'assignment' and 'value' both.  I would
>> insist that the term 'binding' be used instead, though if you want to
>> use the verb refer, to be synonymous with bind, well, I think that
>> would work.  (If not, next trip with the time machine, I ban that one
>> as well.)  Then you make it perfectly clear that what are bound are
>> _objects_ not values (or evalues).  The object has an evalue, but it
>> is the object that is bound.
>
> Not far enough back. Since there are older languages with the same
> assignment semantics as python, you should at least go so far.

Back to 1958 or so when Lisp was LISP and the association of names with
whatever they named was represented as "association lists" (singly
linked lists of key-keyed pairs), or possibly as "property lists"
(singly linked lists with alternative elements being the key and the
keyed). Other arrangements are known. Such a list would have the role
that namespaces have in Python. One could replace the named thing. Then
the name would be associated with something else when that same list
still served as the namespace.

This node (point b) in reminiscenses by John McCarthy himself refers to
the "pseudo-functions" rplaca and rplacd that can replace components of
these data structures (the "a" and "d" refer to the "address part" and
the "decrement part" of a register).
<http://www-formal.stanford.edu/jmc/history/lisp/node4.html>

In point d, McCarthy refers to variables as variables; I'm sure this
would go back to Church and 1940's at least, so I expect they used this
word already back then. But the ability to store new content to the data
structure that associates variables with stuff must be newer. I think it
was new with LISP.

I don't know if assignment was originally called assignment, or whether
the association of names with stuff was originally called binding, but
this terminology is old enough that I've known binding and assignment of
variables by these names for as long as I can remember, with more or
less the semantics that Python now uses. "Rebinding" I've not known
elsewhere.

> Otherwise you would get the argument why one shouldn't use the
> word assignment in python, while other languages use it for the
> same kind of thing.

I think the argument is just that: One shouldn't use otherwise standard
terminology in connection with Python. (With the possible exception of
the Python language reference.) Because people might be confused. (Other
people's confusion doesn't matter. And does the terminology ban even
help?) Also, C is different! (Only C matters. Because no reasons.)

That became snarky in the end. The trouble is that my mental model and
terminology serve me really well when I work in Python.


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 07:25:23 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 13:25:23 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5655A8B3.6000103@rece.vub.ac.be>

Op 25-11-15 om 11:52 schreef Steven D'Aprano:
> On Wed, 25 Nov 2015 07:14 pm, Antoon Pardon wrote:
>
>> Op 20-11-15 om 01:33 schreef Steven D'Aprano:
>>> On Fri, 20 Nov 2015 07:57 am, Marko Rauhamaa wrote:
>>>
>>>> Laura Creighton <lac at openend.se>:
>>>>
>>>>> My experience says that the people who are confused want lists to
>>>>> behave like tuples. period. i.e. they don't want lists to be mutable.
>>>> I think it's simpler than that. When you have:
>>>>
>>>>    def f(x=[]):
>>>>        y = []
>>>>
>>>> the first [] is evaluated when "def" is executed, while the latter [] is
>>>> evaluated whenever "f" is executed. It's easy to be confused.
>>> It shouldn't be. The function declaration
>>>
>>>     def f(x=[]):
>>>
>>> is executed only once. The function body, conveniently indented to make
>>> it stand out:
>>>
>>>         y = []
>>>
>>> is executed every time you call the function.
>> What exactly is your point? 
> That there is a simple analogy between the distinction between code
> inside/outside a for-loop, and code inside/outside a function. If you can
> understand why this loops forever, instead of just twice, then you can
> understand why function defaults work the way they do:
>
> L = [1, 2]
> for i in L:
>     L.append(i)
>     print(L)
>
>
> There is nothing "bizarre" or complicated or difficult to understand
> happening here. It might not be what you want to happen. It might not be
> what you expect to happen. But if you can't understand why it happens even
> after multiple explanations, then your learning skills are severely
> lacking.

You shouldn't equate that what you understand with what is not bizarre
complicated or difficult.

I think there are reasons to find the above behaviour bizarre. I personnaly
don't find it bizarre, but that is because I'm familiar with what is going
on. But if someone expects the compilor to take a snapshot of L and iterate
over that I am not going to say he shouldn't have expected that.

And IMO each time you proclaim something nothing bizarre or complicated
or difficult you are not helping.

>> People's confusions don't disappear 
>> because you as an expert have a good understanding of what is
>> going on and so are no longer confused.
> I'm an expert? Awesome!
>
> No. But people's confusion would disappear if they would:
>
> - think about the process
> - try to follow the steps of what is happening
> - pay attention to the explanations given
> - and ask for clarification instead of arguing.

People would be more inclined to do so, if there wasn't someone
claiming there was nothing bizarre or complicated or difficult
going on. Telling the above is implying those steps are not
needed because it is obvious what is happening. And if you
don't want people arguing, don't start yourself. Because my
impression of what is most likely to happen when someone says
something like: That is bizarre, is that the regulars here
are the ones that start arguing about it not being bizarre
and then they are annoyed that the other is arguing too.

> I have come to the conclusion that there is nobody as stupid as an
> intelligent person who refuses to learn.

Sure but that works just as much for the regulars here, who despite
that some subjects keep confusing people new to the language, keep
repeating that there is nothing bizarre, complicated or difficult
going on.

>> Some aspects in the langauage are easily grasped and other
>> aspects tend to create confusion. 
> You're right. Some aspects of the language are inherently confusing and hard
> to reason about. Threads are an example of that. The more powerful, and
> tricky, aspects of regular expressions. The weird stuff that happens during
> interpreter shutdown if you have __del__ methods in your objects. __del__
> methods in general. There are many things which are hard to reason about,
> and therefore confusing.
>
> *This is not one of them.*

Please stop using your personal evaluation as if it is some kind of
objective measure. The number of people that seem to get confused by
this, contradicts your claim.

> But is it predictable or intuitive? No, I agree, this behaviour is not
> intuitive, if you are coming from a background without equivalent rules. I
> will completely grant you that most people without Python experience would
> not correctly predict the behaviour of mutable defaults.
>
> I was caught out on that too, as I already admitted. Even though I already
> knew all the facts I needed to predict the behaviour correctly, I didn't
> put 2+2 together and get 4. That's *my bad*, not the language's fault.

Why not? People are not perfect rational thinking machines. And expecting
them to act like ones in order to get the language out of the wind, is
a rather weak argument IMO.

> How much harder must it be for those who don't know the essential facts? I
> don't expect anyone to intuit the behaviour of Python defaults. That would
> be unreasonable. There's no shame in guessing wrong from a position of
> ignorance.
>
> Me, on the other hand... I should have known better. I did know better.
>
> But there's a big difference between those who guess wrong from a position
> of ignorance, and then make an honest attempt to understand the behaviour
> and why it actually does make sense and is even sometimes useful (even if
> they don't like it), and those people who insist that it is nonsensical,
> magical and "bizarre".

There is an equally big difference between trying to explain what is going
on and insisting that what is going on is not bizarre.

-- 
Antoon.



From bc at freeuk.com  Wed Nov 25 07:35:32 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 12:35:32 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.56.1448440353.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
Message-ID: <n349qb$qj4$1@dont-email.me>

On 25/11/2015 08:32, Chris Angelico wrote:
> On Wed, Nov 25, 2015 at 7:14 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> What exactly is your point? People's confusions don't disappear
>> because you as an expert have a good understanding of what is
>> going on and so are no longer confused.
>>
>> Some aspects in the langauage are easily grasped and other
>> aspects tend to create confusion. I see nothing wrong with
>> people trying to point out what the cause of this confusion
>> could be. You arguing that people shouldn't be confused is
>> not helping.
>
> "Oh come on. It's basic arithmetic. You should be able to add 7 and
> 7... the result's 14!"
>
> "But it's so confusing. Why can't it be 16? It'd be more convenient
> for me if it were 16."
>
> "This is just how arithmetic works."
>
> "But it's still confusing!"
>
> At some point, you have to simply accept that this is how the system
> works.. or use a different system. (Octal maybe.) If you are
> perpetually confused by Python, you need to either learn how Python
> works, or use something else.

What is the purpose of the language, to make things easier for people or 
what? And who is it for?

In other forums I've frequently recommended Python as an easy to learn 
language with a rapid development cycle. That was before I knew it had 
nearly as many quirks and gotchas as C!

That was in preference to other choices which I found difficult and also 
elitist because of the advanced knowledge of CS and mathematics that it 
seemed you were expected to know. (Eg Lisp, which has at least 4 
different ways of comparing for equality. Python only has two that I 
know of. A simple language would have only one, although my own has 
recently graduated from one to two; it's no longer simple!)

One gotcha at least is well known. Where, in a language of the least 
surprises, you might write:

  d1 = date (25,12,2010)
  d2 = d1
  d2.year += 1

You would expect d1 and d2 to represent a period one year apart. In 
Python, they would both be the later date.

OK, so both names are bound to the same object-value. So then you try this:

a = 10
b = a
b += 1

'+=' is an 'in-place add', so you might expect different semantics from 
'b = b+1'. But no, a isn't changed (disappointingly!).

Then, from the point of view of a beginner, you have two distinct ways 
of representing a list of objects: a tuple and a list. Exactly why there 
have to be two is never really made clear beyond the inadequate 
explanation that one is immutable and the other mutable.

OK, but now I have to continuously think about whether this 
multiple-set-of-objects is going to be a tuple or a list, or something 
else entirely (my date example above I think needs to be a class in 
Python, so that's a third way of doing things. Plus there is something 
called a 'set' that I haven't played with yet).

 > or use something else.

Python isn't as bad as some languages, but it's well on the way. But is 
there anything simpler around that is also well-supported?

-- 
Bartc


From framstag at rus.uni-stuttgart.de  Wed Nov 25 07:44:00 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Wed, 25 Nov 2015 12:44:00 +0000 (UTC)
Subject: readline and TAB-completion?
References: <n33mde$bgg$1@news2.informatik.uni-stuttgart.de>
 <mailman.63.1448444665.20593.python-list@python.org>
Message-ID: <n34aeg$h37$1@news2.informatik.uni-stuttgart.de>

Peter Otten <__peter__ at web.de> wrote:

> > Is there a way to make TAB-completion work for other directories, too?
> 
> Remove "/" from the set of delimiters:
> 
> readline.set_completer_delims(
>     "".join(c for c in readline.get_completer_delims() if c != "/"))

Great!


> > murksigkeiten
> 
> I wonder what's in there ;)
 
Fexed to you :-)

 
-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From marko at pacujo.net  Wed Nov 25 07:48:21 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 14:48:21 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi>
Message-ID: <87egfent2i.fsf@elektro.pacujo.net>

Jussi Piitulainen <harvest at should.be.invalid>:

> In point d, McCarthy refers to variables as variables; I'm sure this
> would go back to Church and 1940's at least, so I expect they used
> this word already back then. But the ability to store new content to
> the data structure that associates variables with stuff must be newer.
> I think it was new with LISP.

As far as the words "variable" and "binding" go, they are present in
lambda calculus (1929 and on):

   Lambda calculus (also written as ?-calculus) is a formal system in
   mathematical logic for expressing computation based on function
   abstraction and application using variable binding and substitution.
   First formulated by Alonzo Church [...]

   [...]

   The abstraction operator, ?, is said to bind its variable wherever it
   occurs in the body of the abstraction. Variables that fall within the
   scope of an abstraction are said to be bound. All other variables are
   called free.

   <URL: https://en.wikipedia.org/wiki/Lambda_calculus>

In lambda calculus, variables are formal markers that are used during
substitution during reduction (ie, evaluation).

If we were to apply the thinking to Python, we could have:

   def f(x):
       return (x + 3) * x

   def g(x):
       return x * 2 - math.sqrt(x)

Now the Python expression

   f(g(7))

could be reduced as follows:

   f(g(7))
   =>
   (g(7) + 3) * g(7)
   =>
   ((7 * 2 - math.sqrt(7)) + 3) * (7 * 2 - math.sqrt(7))
   =>
   (7 * 2 - 2.6457513110645907) + 3 * (7 * 2 - 2.6457513110645907)
   =>
   [etc]
   
That is, binding/substitution is syntactic/formal. Or, to say it in
another way, lambda calculus is a kind of macro processing language like
cpp or m4.

> I don't know if assignment was originally called assignment, or whether
> the association of names with stuff was originally called binding, but
> this terminology is old enough that I've known binding and assignment of
> variables by these names for as long as I can remember, with more or
> less the semantics that Python now uses. "Rebinding" I've not known
> elsewhere.

I think "binding" is too fancy a word to be used with conventional
programming languages like Python. If your programming language has an
assignment statement, "binding" is even nonsensical. Consider:

   def f(x):
       x += 1
       return 2 * x

Now we would have this reduction:

   f(7)
   =>
   7 += 1; return 2 * 7

because "x" would be bound to "7" everywhere in the function body.


Marko


From marko at pacujo.net  Wed Nov 25 08:06:04 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 15:06:04 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me>
Message-ID: <878u5mns8z.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> That was in preference to other choices which I found difficult and
> also elitist because of the advanced knowledge of CS and mathematics
> that it seemed you were expected to know.

Python is not a toy. It is a tool for advanced programmers.

Mathematics has barely any touching point, but yes, solid CS fluency is
required to be a productive software developer regardless of the
programming language.

Is a plumber an elitist, when he prefers to use tools I wouldn't know
how to operate?

> One gotcha at least is well known. Where, in a language of the least
> surprises, you might write:
>
>  d1 = date (25,12,2010)
>  d2 = d1
>  d2.year += 1
>
> You would expect d1 and d2 to represent a period one year apart. In
> Python, they would both be the later date.

No elitism or expertise would help you "expect" any outcome. I wouldn't
even expect d2 to have a field called "year". That's why you read the
specification.

> Then, from the point of view of a beginner, you have two distinct ways
> of representing a list of objects: a tuple and a list. Exactly why
> there have to be two is never really made clear beyond the inadequate
> explanation that one is immutable and the other mutable.

>From a functional point of view, there don't have to be two separate
concepts. The immutability of tuples is also just a design choice.

However, tuples are a way to represent records, groupings of related
values, where the semantics of each value is determined by its position
in the tuple. The members in a tuple are typically of different data
types.

Lists are collections of values. Typically, each member of list is of
the same type.

Tuples are handy because they allow you to treat multiple values as a
single value. Also, they are syntactically analogous to tuples in
mathematics so chances are you have encountered them in elementary
school. Finally, they are similar to function arguments, allowing you to
return multiple values the same way you pass multiple values to the
function.

> Python isn't as bad as some languages, but it's well on the way. But
> is there anything simpler around that is also well-supported?

My "simpler" is different from your "simpler". Even C# has a lot of
advanced concepts, as maybe even Fortran does nowadays.

My own recommendation would be Scheme, but it is even more "elitist"
than Python.


Marko


From bc at freeuk.com  Wed Nov 25 08:20:31 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 13:20:31 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n34cem$4l5$1@dont-email.me>

On 25/11/2015 10:52, Steven D'Aprano wrote:
> On Wed, 25 Nov 2015 07:14 pm, Antoon Pardon wrote:

>> What exactly is your point?
>
> That there is a simple analogy between the distinction between code
> inside/outside a for-loop, and code inside/outside a function. If you can
> understand why this loops forever, instead of just twice, then you can
> understand why function defaults work the way they do:
>
> L = [1, 2]
> for i in L:
>      L.append(i)
>      print(L)
>
>
> There is nothing "bizarre" or complicated or difficult to understand
> happening here.

What do you think most people would expect to happen here? I know, 
because you gave a spoiler, that it loops forever, otherwise I wouldn't 
be sure /without trying it/ (but I tried it anyway).

Here's the same code in a somewhat different language:

L := (1,2)
for i in L do
|   L append:= i
|   println L
od

And this is the output:

(1,2,1)
(1,2,1,2)

Which output (infinite series of [1,2,1,2,1,....] or the above) is more 
sensible, and which do you think people might prefer?

The point is that the behaviour of the loop is by no means obvious, so 
neither is the behaviour of the function defaults.

> It might not be what you want to happen. It might not be
> what you expect to happen. But if you can't understand why it happens even
> after multiple explanations, then your learning skills are severely
> lacking.

Accept that some things /are/ a source of confusion. When, in writing 
documentation, I find something hard to explain something, then I try 
and make it simpler in the program. But not enough of that goes on: it 
seems to be more lucrative to write thicker user manuals, and provide 
longer training courses, than to make software simpler.

> I really don't know how more clear we can possibly be. If you take a list,
> initialised as the empty list ONCE, and then modify it repeatedly, the list
> doesn't magically become empty just because you want it to be empty.

Sure. The problem is that it might not be obvious it's initialised once.

> I completely understand beginners making this mistake:
>
> # Simulate tossing a coin until it is heads.
> count = 1
> coin = random.choice(['heads', 'tails'])
> while coin != 'heads':
>      count += 1
>
> "Why does the loop run forever?"
>
> The coin doesn't magically toss itself, no matter how intuitively obvious it
> is that it should.

The concept of variables doesn't take long to learn in an 'ordinary' 
language.

But one problem with Python is that it gives the impression that almost 
anything is possible. Your example can be made to work with a slight tweak:

  count = 1
  coin = lambda: random.choice(['heads', 'tails'])
  while coin() != 'heads':
       count += 1

In some languages, there would never be such a possibility because they 
don't have the extraordinary flexibility and dynamism of Python. But 
once you get the idea that the language can almost do magic, then it 
doesn't seem so far-fetched that you original example could work!

> Just like functions. If you want code to run each time you call the
> function, PUT IT INSIDE THE FUNCTION BODY.

Many languages don't have the concept of code running outside a function 
body. And especially they don't have the truly bizarre one that a 
function definition is itself a piece of code that is executed. Or maybe 
not executed, if it's inside a conditional statement! And therefore does 
not exist. This is an extra hurdle with learning or even using this 
language.

-- 
bartc


From rosuav at gmail.com  Wed Nov 25 08:24:32 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 00:24:32 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <5655A8B3.6000103@rece.vub.ac.be>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <5655A8B3.6000103@rece.vub.ac.be>
Message-ID: <CAPTjJmq8+jERjPrcnWrDu7A4OMUigF=Vv=SwokQA6Q0Wb85kjQ@mail.gmail.com>

On Wed, Nov 25, 2015 at 11:25 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
>> But there's a big difference between those who guess wrong from a position
>> of ignorance, and then make an honest attempt to understand the behaviour
>> and why it actually does make sense and is even sometimes useful (even if
>> they don't like it), and those people who insist that it is nonsensical,
>> magical and "bizarre".
>
> There is an equally big difference between trying to explain what is going
> on and insisting that what is going on is not bizarre.

There is also a big difference between finding that something doesn't
match your expectations and declaring that it is "bizarre", which
implies that it makes no sense *to anyone*. What we've been pointing
out to you is that Python's way *does* make sense - just a different
sense from the one you're expecting.

There are many design decisions in programming languages. I've used
languages that have myriad keywords, multiple levels of keywords (SQL
is a shocking mess in that area), or no keywords at all (in REXX, you
can legally write "if if then then; else else", and it interprets
three of those as structure-defining and three as identifiers). I've
used languages where everything's a statement, even basic arithmetic.
Some languages make you declare your local variables, while others
have you declare your globals instead. These are all viable choices,
and they all make sense. The languages are internally coherent. I
would not call any of them "bizarre", with the possible exception of
DeScribe Macro Language, and even that's not too hard to get your head
around. (I wouldn't want to use it for any sort of general
programming, though. Its sole value is manipulating the DeScribe Word
Processor, and if you were to use it for something else, you'd have to
expand the language lexicon. There's no system of extensibility.)

Expanding on one of those examples, here are three ways that you can
distinguish between local/nonlocal/global variables/names/etc:

/* C++: Declare everything at a specific scope. */
int global_variable = 1;

struct outer_scope
{
    int instance_variable;
    void inner_scope()
    {
        int local_variable = 3;
    }
};

/* PHP: Declare your globals, otherwise they're local. */
$global_variable = 1;
function outer_function()
{
    global $global_variable;
    $local_variable = 2;
    /* I don't trust PHP's nested functions. */
}

# Python: Declare any globals you want to rebind.
global_name = 1
def outer_function():
    nonlocal_name = 2
    def inner_function():
        global global_name
        local_name = 3

There are variations on these, too (like ECMAScript's "declare and
it's function local, else it's an attribute of the global object").
Anyway. Point is, each of these systems is internally consistent, and
in each one, you can explain in a single sentence what the rule is.
Not one of these is bizarre, but I do completely understand that
anyone who has experience with just one of them _would_ find either of
the others confusing at first. "Wait, why do you need to declare this
as global, but not that?" "You're not assigning to that one, so you
don't need to declare it."

If you want to call Python's system "bizarre", you have to show more
than just that your expectations weren't matched by the language. You
have to show that Python lacks internal sense or consistency. You
have, so far, not shown anything of the kind, ergo we are continuing
to insist that Python is NOT bizarre.

ChrisA


From rosuav at gmail.com  Wed Nov 25 08:35:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 00:35:38 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n349qb$qj4$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me>
Message-ID: <CAPTjJmrtksaTvU180ERbK0TgYagqsK4R_j=yk0hcNAmoRsqiOQ@mail.gmail.com>

On Wed, Nov 25, 2015 at 11:35 PM, BartC <bc at freeuk.com> wrote:
> One gotcha at least is well known. Where, in a language of the least
> surprises, you might write:
>
>  d1 = date (25,12,2010)
>  d2 = d1
>  d2.year += 1
>
> You would expect d1 and d2 to represent a period one year apart. In Python,
> they would both be the later date.

I'm not sure why this is "a language of least surprises". It's just a
language of *different* surprises. I'll give you an example of exactly
that: PHP has semantics similar to what you're describing.

$ php
<?php
$a = array("foo", "bar");
$b = $a;
$b[1] = "baz";
print_r($a);
^D
Array
(
    [0] => foo
    [1] => bar
)

I'm not exactly sure of the definition of PHP's assignment, as it's
been a while since I looked it up; but it seems to be something like
what you're describing. This seems well and good, until you start
contemplating gigantic arrays and what happens when you pass them from
one function to another. What're your performance expectations? With
Python, I know that "a = b" happens in constant time, and I also know
that the performance of "a[1]=2" is not going to be affected by any
other names that might be bound to the same object. PHP's references
make this even more messy:

$ php
<?php
$a = array("foo", "bar");
$b = &$a[1];
$b = $a;
$b[1] = "baz";
print_r($a);
^D
Array
(
    [0] => foo
    [1] => baz
)

So... since I'd previously set $b to be a reference, now assigning to
it does something different. And what, exactly? Is $a[1] the exact
same array as $a? Has any copying happened? When I change $b[1], is
that the same as changing $a[1], or is it actually changing $a[1][1],
and is that even any different?

This isn't a magical solution to all surprises, except perhaps in that
you've built a language yourself, so it conforms perfectly to *your*
expectations. You can never make something that fits everyone's
expectations, so you'll always have surprises somewhere. It's just a
question of where, and how easily they can be explained when someone
runs into them.

ChrisA


From bc at freeuk.com  Wed Nov 25 08:37:59 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 13:37:59 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <878u5mns8z.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
Message-ID: <n34dfe$8n5$1@dont-email.me>

On 25/11/2015 13:06, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:

>> Then, from the point of view of a beginner, you have two distinct ways
>> of representing a list of objects: a tuple and a list. Exactly why
>> there have to be two is never really made clear beyond the inadequate
>> explanation that one is immutable and the other mutable.

> However, tuples are a way to represent records, groupings of related
> values, where the semantics of each value is determined by its position
> in the tuple. The members in a tuple are typically of different data
> types.

Using tuples in the same way that other languages implement records is 
going to be difficult if you can't change the values of the fields!

> My "simpler" is different from your "simpler". Even C# has a lot of
> advanced concepts, as maybe even Fortran does nowadays.
>
> My own recommendation would be Scheme, but it is even more "elitist"
> than Python.

OK, Lisp. (I can't actually tell the difference.)

-- 
Bartc


From rosuav at gmail.com  Wed Nov 25 08:44:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 00:44:38 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <878u5mns8z.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmoyGi04Dnxxp1AFytLkWQg=D4ccXqE6OwfJJMgp7fg1YA@mail.gmail.com>

On Thu, Nov 26, 2015 at 12:06 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> However, tuples are a way to represent records, groupings of related
> values, where the semantics of each value is determined by its position
> in the tuple. The members in a tuple are typically of different data
> types.
>
> Lists are collections of values. Typically, each member of list is of
> the same type.

This is a distinction I generally make. Putting it another way: a list
has the same meaning regardless of how many items are on it (for
instance, a shopping list is still a shopping list whether it has five
or fifty items on it), where a tuple is a package where each element
has a specific meaning (such as Cartesian coordinates; the difference
between the position (2,3) and the position (2,3,4) is not just that
there's "more position" in the second one - it's a drastically
different beast, living in three dimensions instead of two).

Nothing in the language enforces this, but the mutability of lists
does tend to align well with things that can grow and shrink, and the
immutability of tuples makes them more like strings or complex numbers
(in fact, a complex number is basically a tuple of two floats).

ChrisA


From rosuav at gmail.com  Wed Nov 25 08:50:59 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 00:50:59 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <87egfent2i.fsf@elektro.pacujo.net>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi>
 <87egfent2i.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqpO1_yOS7T0hCAwz2JcLBY_PYbB_p-FoYpuJ15hmj7pg@mail.gmail.com>

On Wed, Nov 25, 2015 at 11:48 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> I think "binding" is too fancy a word to be used with conventional
> programming languages like Python. If your programming language has an
> assignment statement, "binding" is even nonsensical. Consider:
>
>    def f(x):
>        x += 1
>        return 2 * x
>
> Now we would have this reduction:
>
>    f(7)
>    =>
>    7 += 1; return 2 * 7
>
> because "x" would be bound to "7" everywhere in the function body.

This is exactly the sort of problem that inevitably happens when you
try to extend mathematics into programming. Most branches of
mathematics are simply looking at pure, eternal statements of truth;
if once you discover (or decide) that x is equal to 7, you can
perfectly substitute one for the other in any context. There is no
chronology - x has always been equal to 7, you just didn't know it
until now. It's possible to write code this way, and there are
benefits to it, but as soon as you have an assignment operator, you're
introducing a whole aspect of chronological truth that math lacks, so
some concepts ARE going to need to be modified.

However, that doesn't stop us from making use of terminology, where
it's helpful. We know from grade school that adding two numbers
together and dividing by 2 gives us the average, or the midpoint
between them. Programming languages introduce the notion of adding two
strings together, and also throw the curve-ball at us that sometimes
the average isn't the same as the perfect mathematical average (due to
rounding or other issues). But we'll still call that operation adding,
and we'll still have avg() functions that do what we broadly expect.

ChrisA


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 08:51:23 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 14:51:23 +0100
Subject: What does a list comprehension do (was: Late-binding of function
 defaults (was Re: What is a function parameter =[] for?))
In-Reply-To: <877fldnm9z.fsf@handshake.de>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
Message-ID: <5655BCDB.4020905@rece.vub.ac.be>

Op 20-11-15 om 08:49 schreef dieter:
> In addition, the last few days have had two discussions in this list
> demonstrating the conceptial difficulties of late binding -- one of them:
>
>       Why does "[lambda x: i * x for i in range(4)]" gives
>       a list of essentially the same functions?

Can you (or someone else) explain what a list comprehension is equivallent of.
Especially in python3.

Take this simple list comprhesion:

[x * x for x in range(10)]

what would this be equivallent of? Something like:

def lch1():
  ls = []
  for x in range(10):
    ls.append(x * x)
  return ls

Or more something like:

def lch2():
  def expr(x):
    return x * x

  ls = []
  for x in range(10):
    ls.append(expr(x))
  return ls

For this example it doesn't make a difference but for the example above
it would become important.

def lch3():
  ls = []
  for i in range(4):
    ls.append(lambda x: i * x)
  return ls

versus

def lch4():
  def expr(i):
    return lambda x: i * x

  ls = []
  for i in range(4)
    ls.append(expr(i))
  return ls

Now from the result we get I expect list comprehensions to work more
like lch1 and lch3 rather than lch2 and lch4. But I can understand
people who think of the expression as a function of the variable that
is iterated over.

Am I missing something? Would it be worthwile considering changing
this behaviour?

-- 
Antoon.



From marko at pacujo.net  Wed Nov 25 08:53:01 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 15:53:01 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me>
Message-ID: <874mganq2q.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> Using tuples in the same way that other languages implement records is
> going to be difficult if you can't change the values of the fields!

Guido could decide tomorrow that tuples are mutable. The decision is
more or less arbitrary, and has to do with dictionary keys, I bet (not a
particularly good reason).

Anyway, Python has two ways to represent records: classes and tuples.
Tuples are nice because they are concise and ad hoc. Often you start
with a scalar value, then turn it into a tuple. After a while your handy
tuple turns out a bit cumbersome to use so you convert it into an actual
class.


Marko


From marko at pacujo.net  Wed Nov 25 09:08:26 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 16:08:26 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi> <87egfent2i.fsf@elektro.pacujo.net>
 <mailman.72.1448459462.20593.python-list@python.org>
Message-ID: <87ziy2masl.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Wed, Nov 25, 2015 at 11:48 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> I think "binding" is too fancy a word to be used with conventional
>> programming languages like Python. If your programming language has
>> an assignment statement, "binding" is even nonsensical. Consider:
>>
>>    def f(x):
>>        x += 1
>>        return 2 * x
>>
>> Now we would have this reduction:
>>
>>    f(7)
>>    =>
>>    7 += 1; return 2 * 7
>>
>> because "x" would be bound to "7" everywhere in the function body.
>
> This is exactly the sort of problem that inevitably happens when you
> try to extend mathematics into programming. Most branches of
> mathematics are simply looking at pure, eternal statements of truth;
> if once you discover (or decide) that x is equal to 7, you can
> perfectly substitute one for the other in any context. There is no
> chronology - x has always been equal to 7, you just didn't know it
> until now. It's possible to write code this way, and there are
> benefits to it, but as soon as you have an assignment operator, you're
> introducing a whole aspect of chronological truth that math lacks, so
> some concepts ARE going to need to be modified.
>
> However, that doesn't stop us from making use of terminology, where
> it's helpful.

I think that's the point. Binding is a concept of a formal (textual)
substitution algorithm, which Python's assignment is not.

   Variable-binding mechanisms occur in different contexts in
   mathematics, logic and computer science. In all cases, however, they
   are purely syntactic properties of expressions and variables in them.

   <URL: https://en.wikipedia.org/wiki/Free_variables_and_bound_variable
   s#Formal_explanation>


Marko


From glicerinu at gmail.com  Wed Nov 25 09:10:31 2015
From: glicerinu at gmail.com (Marc Aymerich)
Date: Wed, 25 Nov 2015 15:10:31 +0100
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
 <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
 <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>
 <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>
Message-ID: <CA+DCN_vojbps5F_7+r4-ijdYPjhCqMQyBRGK_ijRic1dFa_Rsg@mail.gmail.com>

On Tue, Nov 24, 2015 at 9:17 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
> On Tue, Nov 24, 2015 at 8:41 PM, Zachary Ware
> <zachary.ware+pylist at gmail.com> wrote:
>> On Tue, Nov 24, 2015 at 12:37 PM, Marc Aymerich <glicerinu at gmail.com> wrote:
>>> still it appears to work only if the main thread is in the foreground
>>> (as of calling Thread() with deamon=True), I don't get why it behaves
>>> differently :( maybe it is waiting for other stuff, but no idea how to
>>> confirm this with strace of other means.. i always see the same
>>> 'futex(0x7f9a70000c10, FUTEX_WAIT_PRIVATE, 0, NULL'
>>
>> What's your exact version of Python?  asyncio is still evolving
>> rapidly, and may behave differently between patch releases (say,
>> between 3.4.1 and 3.4.3).
>>
>> I have tried out your reproducer with my fix, and I can't provoke a
>> hang using Python 3.4.3 on either OSX or Ubuntu Trusty.  Can you give
>> some more specific directions to reproduce?
>>
>> --
>> Zach
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>
>
> Yep, I'm a bit lost about how fuse implements going into background...
> so the only way I have to reproduce this so far is by using fuse :(


problem solved !
Just found out that threads should be started by fuse.init() in order
to run when fuse is backgrounded.


-- 
Marc


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 09:17:43 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 15:17:43 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <CAPTjJmq8+jERjPrcnWrDu7A4OMUigF=Vv=SwokQA6Q0Wb85kjQ@mail.gmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <5655A8B3.6000103@rece.vub.ac.be>
 <CAPTjJmq8+jERjPrcnWrDu7A4OMUigF=Vv=SwokQA6Q0Wb85kjQ@mail.gmail.com>
Message-ID: <5655C307.7020003@rece.vub.ac.be>

Op 25-11-15 om 14:24 schreef Chris Angelico:
> On Wed, Nov 25, 2015 at 11:25 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>>> But there's a big difference between those who guess wrong from a position
>>> of ignorance, and then make an honest attempt to understand the behaviour
>>> and why it actually does make sense and is even sometimes useful (even if
>>> they don't like it), and those people who insist that it is nonsensical,
>>> magical and "bizarre".
>> There is an equally big difference between trying to explain what is going
>> on and insisting that what is going on is not bizarre.
> There is also a big difference between finding that something doesn't
> match your expectations and declaring that it is "bizarre", which
> implies that it makes no sense *to anyone*. What we've been pointing
> out to you is that Python's way *does* make sense - just a different
> sense from the one you're expecting.

I find the above a very defensive attitude. People are mostly not
very accurate in how they put things into words. People tend to
say that something was delicious instead of saying that they
found it delicious. So when someone declares as aspect of python
to be bizarre I interpret that as an indication of what impression
that aspect made on that person instead of some declaration of fact.
So stop feeling attacked because someone found something bizarre.

You also seem to think that bizarre contradicts making sense. It
is entirly possible to understand what is going on and still find
it bizarre that the designers allowed for certain kinds or result.

> If you want to call Python's system "bizarre", you have to show more
> than just that your expectations weren't matched by the language. You
> have to show that Python lacks internal sense or consistency. You
> have, so far, not shown anything of the kind, ergo we are continuing
> to insist that Python is NOT bizarre.

No I don't have to show any such thing. There are things with an internal
sense of consistency that can be found utterly bizarre. I also find it
telling that you go from me talking about someone thinking that what is
going on in a specific aspect of python being bizarre, to regarding 
such a person as calling Python's system "bizarre", as if judging one
aspect is like judging the whole system. 

-- 
Antoon.




From bc at freeuk.com  Wed Nov 25 09:34:12 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 14:34:12 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <874mganq2q.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
Message-ID: <n34gor$kq8$1@dont-email.me>

On 25/11/2015 13:53, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:
>
>> Using tuples in the same way that other languages implement records is
>> going to be difficult if you can't change the values of the fields!
>
> Guido could decide tomorrow that tuples are mutable.

(Could that be done without breaking existing code? And what then would 
be the difference between them and lists?)

> Anyway, Python has two ways to represent records: classes and tuples.
> Tuples are nice because they are concise and ad hoc. Often you start
> with a scalar value, then turn it into a tuple. After a while your handy
> tuple turns out a bit cumbersome to use so you convert it into an actual
> class.

This is how records are handled in another language which I believe is 
simpler than Python: http://pastebin.com/vhsJML8U

This also implements my example from earlier in the thread. Now compare 
with Python's approach.

OK, that also needs two concepts, a list, and a record. But the 
distinction is now completely obvious. Records are also mutable. It 
would also be clear why you can't append to a record.

Now try explaining again to me how you would use tuples for the same 
thing...

-- 
Bartc


From harvest at should.be.invalid  Wed Nov 25 10:13:38 2015
From: harvest at should.be.invalid (Jussi Piitulainen)
Date: Wed, 25 Nov 2015 17:13:38 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi> <87egfent2i.fsf@elektro.pacujo.net>
Message-ID: <lf54mgaxgbh.fsf@ling.helsinki.fi>

Marko Rauhamaa writes:

> Jussi Piitulainen writes:
>
>> In point d, McCarthy refers to variables as variables; I'm sure this
>> would go back to Church and 1940's at least, so I expect they used
>> this word already back then. But the ability to store new content to
>> the data structure that associates variables with stuff must be
>> newer.  I think it was new with LISP.
>
> As far as the words "variable" and "binding" go, they are present in
> lambda calculus (1929 and on):

So it's more than ten years earlier than I thought. Old enough, anyway.
Strictly speaking, that a Wikipedia article uses the words "variable"
and "binding" to discuss lambda calculi today is not a proof that Church
used those words in his time. I'm inclined to believe he did. (Our CS
department had a copy of Church's book. It smelled funny.)

A point is that McCarthy knew about lambda calculus. That's where the
name "lambda" for the binding operator comes from, together with
"variable" and "binding" and the correct scoping rules that other people
worked out quite a bit later.

>> I don't know if assignment was originally called assignment, or
>> whether the association of names with stuff was originally called
>> binding, but this terminology is old enough that I've known binding
>> and assignment of variables by these names for as long as I can
>> remember, with more or less the semantics that Python now
>> uses. "Rebinding" I've not known elsewhere.
>
> I think "binding" is too fancy a word to be used with conventional
> programming languages like Python. If your programming language has an
> assignment statement, "binding" is even nonsensical.

The term has more than fifty years of history in languages that have not
only an assignment statement but also mutable things. It's needed to
speak of where and when in a program the occurrences of an identifier
have what meaning. A statement like x = 31 does not affect every x even
in a Python program, only those that are bound in the same namespace.

In Scheme, a variable is bound to a location where its value is stored.
A variable reference evaluates to that stored value. In Python, one
chooses to say that a mumble is bound to an object, but then there is a
namespace that also serves as a store where one can put a new object,
like one can put a new object in a Python dictionary, and then the
mumble becomes bound to that object instead.

These are different ways to talk about the same thing. (The Scheme way
in a sense "explains" mutable store in terms of mathematical functions
where the Python way takes it for granted, I think). No nonsense.

> Consider:
>
>    def f(x):
>        x += 1
>        return 2 * x
>
> Now we would have this reduction:
>
>    f(7)
>    =>
>    7 += 1; return 2 * 7
>
> because "x" would be bound to "7" everywhere in the function body.

You know, people have developed further ways to talk about these things
precisely because substitution semantics is inadequate for what they
wanted to talk about. See references in that Wikipedia article
(Felleisen might be to the point. The field is called denotational
semantics.)

The description, in the language reference (or is it the library
reference), of how Python function calls are evaluated can be seen as an
example. First the actual arguments and possibly some defaults are put
in fresh locations, then the formal parameters are bound to these in an
order that is a bit complicated because of keyword parameters and such,
but nevertheless *bound* *then*. Not substituted to the program text -
who would even think that? And then the evaluation of the occurrences of
the parameters in the code of the function goes through *these* bindings
rather than any other bindings that might be in effect elsewhere in the
program, including any pending calls of the same function.


From ned at nedbatchelder.com  Wed Nov 25 10:13:41 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Wed, 25 Nov 2015 07:13:41 -0800 (PST)
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n34cem$4l5$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
Message-ID: <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>

On Wednesday, November 25, 2015 at 8:20:59 AM UTC-5, BartC wrote:
> Accept that some things /are/ a source of confusion. When, in writing 
> documentation, I find something hard to explain something, then I try 
> and make it simpler in the program. But not enough of that goes on: it 
> seems to be more lucrative to write thicker user manuals, and provide 
> longer training courses, than to make software simpler.

You seem to be insinuating that someone has made Python unusually complex
for personal gain?  I'm not sure what to do with that: it's an absurd
claim.  

> > "Why does the loop run forever?"
> >
> > The coin doesn't magically toss itself, no matter how intuitively obvious it
> > is that it should.
> 
> The concept of variables doesn't take long to learn in an 'ordinary' 
> language.

There is a natural tension between making a language simple enough that
it has no surprises or difficult parts; and making a language rich
enough that it can be used for building serious systems.

If you have another language to propose as a better beginner's learning
language, please propose it.  I think it serves beginners better to
teach them with a language that they can then go on to use for building
real things.  Is there a real language (an "ordinary" language) that
you think is better than Python for that?  Empirical evidence in the
world says, "not really."

I know you have languages of your own, and that you like the way they
work better.  We have no way of evaluating their power or simplicity,
since they are not available to us.

I agree with you: there are things about Python that surprise people.
That's because it's a programming language, and very very little about
programming languages is obvious.  The best we can hope for is "familiar,"
and even then, familiar to who?  High school algebra students will at
first be baffled by "x = x + 1", an equation which is clearly
unsatisfiable.

So yes, there are parts of Python that are hard, and surprising. There
are subtleties that require study and careful thought.  We believe that
on the balance, Python is better than many of the alternatives. You
are welcome to disagree, but don't be surprised if you encounter
vigorous counter-arguments in a Python mailing list!

There isn't much we can do about the structure of the language, certainly
not the parts that have been discussed in this thread.  The best we can
do is try to explain it better.

--Ned.


From zachary.ware+pylist at gmail.com  Wed Nov 25 10:58:20 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 25 Nov 2015 09:58:20 -0600
Subject: Futex hang when running event loop on a separated thread
In-Reply-To: <CA+DCN_vojbps5F_7+r4-ijdYPjhCqMQyBRGK_ijRic1dFa_Rsg@mail.gmail.com>
References: <CA+DCN_s77howCh5ptdGwtsF9Z3-r0nRhu-q2t43jdXKTdqSMGw@mail.gmail.com>
 <CA+DCN_vp8nFS-gOrQMYYefhVt2W0oAP+rFcKQbQ7K+hOHwvuuQ@mail.gmail.com>
 <CAKJDb-MY9W518kKhFf8vbZAfFad=uGXefDePf1KLpUJV9H3Rpg@mail.gmail.com>
 <CA+DCN_uC2k=rJxmtfEideAhGj1=2XVq8VHGU=OUkB9yHxV7bPw@mail.gmail.com>
 <CAKJDb-N5WD_cN2k0kd_aXXyj_2Bsjxye8Q34_3awtw7bGPRx5w@mail.gmail.com>
 <CA+DCN_uNHNHrBOSmd0JE58Ltt6HzrDWU_DhW_1N3dFMAVNpVOQ@mail.gmail.com>
 <CA+DCN_vojbps5F_7+r4-ijdYPjhCqMQyBRGK_ijRic1dFa_Rsg@mail.gmail.com>
Message-ID: <CAKJDb-OXwKR6gBxsgRFpKq4bNqYNJgC68z6a-JCu4F52_ACKXw@mail.gmail.com>

On Wed, Nov 25, 2015 at 8:10 AM, Marc Aymerich <glicerinu at gmail.com> wrote:
> problem solved !
> Just found out that threads should be started by fuse.init() in order
> to run when fuse is backgrounded.

Glad you found it; I would not have, not being a pyfuse user :)

-- 
Zach


From lac at openend.se  Wed Nov 25 10:59:31 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 25 Nov 2015 16:59:31 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
Message-ID: <201511251559.tAPFxVm6020346@fido.openend.se>

In a message of Wed, 25 Nov 2015 07:13:41 -0800, Ned Batchelder writes:
>That's because it's a programming language, and very very little about
>programming languages is obvious.  The best we can hope for is "familiar,"
>and even then, familiar to who?  High school algebra students will at
>first be baffled by "x = x + 1", an equation which is clearly
>unsatisfiable.

The great sticking point for the children I am teaching is
'*' means multiplication.  You can really see that some people 
have to make extensive mental modifications in order to handle
the concept that mathematical truths are expressed in linguistic
and orthographic conventions, and that one can swap out a particular
convention 'x means multiply' and swap in another one '* means
multiply' while leaving the underlying truth unchanged.

Laura


From xapwing at gmail.com  Wed Nov 25 11:12:58 2015
From: xapwing at gmail.com (Arie van Wingerden)
Date: Wed, 25 Nov 2015 17:12:58 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
Message-ID: <CADkALSH-KsUwahaA6EB=DCiqeO-fB8giQodb=VJvZWpUxh+HCQ@mail.gmail.com>

>and even then, familiar to who?  High school algebra students will at
>first be baffled by "x = x + 1", an equation which is clearly
>unsatisfiable.
Some languages are "better" in that specific case in my opinion (mind te
double quotes :-)
   - Ada and Pascal use := instead of = which is simpler to grasp for n00bs
(I think)
   - Erlang uses pattern matching. So when left hand side does NOT right
hand side, yuou get an exception.
         Each variable can be only assigned once and only once.
         That is the most purely mathematical approach (I think)
   - Haskell


2015-11-25 16:13 GMT+01:00 Ned Batchelder <ned at nedbatchelder.com>:

> On Wednesday, November 25, 2015 at 8:20:59 AM UTC-5, BartC wrote:
> > Accept that some things /are/ a source of confusion. When, in writing
> > documentation, I find something hard to explain something, then I try
> > and make it simpler in the program. But not enough of that goes on: it
> > seems to be more lucrative to write thicker user manuals, and provide
> > longer training courses, than to make software simpler.
>
> You seem to be insinuating that someone has made Python unusually complex
> for personal gain?  I'm not sure what to do with that: it's an absurd
> claim.
>
> > > "Why does the loop run forever?"
> > >
> > > The coin doesn't magically toss itself, no matter how intuitively
> obvious it
> > > is that it should.
> >
> > The concept of variables doesn't take long to learn in an 'ordinary'
> > language.
>
> There is a natural tension between making a language simple enough that
> it has no surprises or difficult parts; and making a language rich
> enough that it can be used for building serious systems.
>
> If you have another language to propose as a better beginner's learning
> language, please propose it.  I think it serves beginners better to
> teach them with a language that they can then go on to use for building
> real things.  Is there a real language (an "ordinary" language) that
> you think is better than Python for that?  Empirical evidence in the
> world says, "not really."
>
> I know you have languages of your own, and that you like the way they
> work better.  We have no way of evaluating their power or simplicity,
> since they are not available to us.
>
> I agree with you: there are things about Python that surprise people.
> That's because it's a programming language, and very very little about
> programming languages is obvious.  The best we can hope for is "familiar,"
> and even then, familiar to who?  High school algebra students will at
> first be baffled by "x = x + 1", an equation which is clearly
> unsatisfiable.
>
> So yes, there are parts of Python that are hard, and surprising. There
> are subtleties that require study and careful thought.  We believe that
> on the balance, Python is better than many of the alternatives. You
> are welcome to disagree, but don't be surprised if you encounter
> vigorous counter-arguments in a Python mailing list!
>
> There isn't much we can do about the structure of the language, certainly
> not the parts that have been discussed in this thread.  The best we can
> do is try to explain it better.
>
> --Ned.
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From rosuav at gmail.com  Wed Nov 25 11:29:41 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 03:29:41 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
Message-ID: <CAPTjJmr+cK62E5VebY1poaE5axdVawmMbQ+TxM5LxN2m=DXHyQ@mail.gmail.com>

On Thu, Nov 26, 2015 at 2:13 AM, Ned Batchelder <ned at nedbatchelder.com> wrote:
> I agree with you: there are things about Python that surprise people.
> That's because it's a programming language, and very very little about
> programming languages is obvious.  The best we can hope for is "familiar,"
> and even then, familiar to who?  High school algebra students will at
> first be baffled by "x = x + 1", an equation which is clearly
> unsatisfiable.

And then *lots* of people are confused by "x += 1" being almost, but
not entirely, identical to the above. Actually, if there were one
change I could make to Python, it would be to redefine the augmented
assignment operators to be semantically identical to their expanded
forms; there might be some optimizations, but absolutely no difference
in effect. (Which would mean, among other things, that it would be a
very bad way to append to a list, instead of being an alias for
.extend.)

ChrisA


From marko at pacujo.net  Wed Nov 25 11:44:42 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 18:44:42 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi> <87egfent2i.fsf@elektro.pacujo.net>
 <lf54mgaxgbh.fsf@ling.helsinki.fi>
Message-ID: <877fl66nb9.fsf@elektro.pacujo.net>

Jussi Piitulainen <harvest at should.be.invalid>:

> Marko Rauhamaa writes:
>> As far as the words "variable" and "binding" go, they are present in
>> lambda calculus (1929 and on):
>
> So it's more than ten years earlier than I thought. Old enough,
> anyway. Strictly speaking, that a Wikipedia article uses the words
> "variable" and "binding" to discuss lambda calculi today is not a
> proof that Church used those words in his time. I'm inclined to
> believe he did. (Our CS department had a copy of Church's book. It
> smelled funny.)

I haven't even smelled the originals, but the formalization of variable
substitution was *the* big selling point for lambda calculus.
Previously, combinatory logic solved the age-old problem with variables
by eliminating them altogether:

   Combinatory logic is a notation to eliminate the need for quantified
   variables in mathematical logic.

   <URL: https://en.wikipedia.org/wiki/Combinatory_logic>

>> Now we would have this reduction:
>>
>>    f(7)
>>    =>
>>    7 += 1; return 2 * 7
>>
>> because "x" would be bound to "7" everywhere in the function body.
>
> You know, people have developed further ways to talk about these things
> precisely because substitution semantics is inadequate for what they
> wanted to talk about.

"Assignment" is what everybody uses and understands.

> Not substituted to the program text - who would even think that?

Actually, if Scheme didn't possess set! et al, we would be talking about
true binding. For example, the function

   (define (sum numbers)
     (let loop ((total 0) (remaining numbers))
       (if (null? remaining)
           total
           (loop (+ total (car remaining)) (cdr remaining)))))

can be described and effectively implemented using true, syntactic
binding. To execute such code, you start with an expression, say,
(sum '(1 2 3 4 5)) and keep on rewriting the expression until you can't
rewrite it anymore.

The availability of set! forces the implementation to generate a memory
slot for each binding, turning the binding semantics into an assignment
semantics.


Marko


From bc at freeuk.com  Wed Nov 25 12:18:44 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 17:18:44 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
Message-ID: <n34qdc$sbp$1@dont-email.me>

On 25/11/2015 15:13, Ned Batchelder wrote:
> On Wednesday, November 25, 2015 at 8:20:59 AM UTC-5, BartC wrote:
>> Accept that some things /are/ a source of confusion. When, in writing
>> documentation, I find something hard to explain something, then I try
>> and make it simpler in the program. But not enough of that goes on: it
>> seems to be more lucrative to write thicker user manuals, and provide
>> longer training courses, than to make software simpler.
>
> You seem to be insinuating that someone has made Python unusually complex
> for personal gain?  I'm not sure what to do with that: it's an absurd
> claim.

Actually I was thinking of certain Microsoft products. But I think my 
point stands: the design of software could be influenced more by the 
documentation. In the case of languages, that's perhaps harder because 
languages tend to evolve, and they usually have to be backwards compatible.

>>> "Why does the loop run forever?"
>>>
>>> The coin doesn't magically toss itself, no matter how intuitively obvious it
>>> is that it should.
>>
>> The concept of variables doesn't take long to learn in an 'ordinary'
>> language.

> There is a natural tension between making a language simple enough that
> it has no surprises or difficult parts; and making a language rich
> enough that it can be used for building serious systems.

Well, with Python I get the impression it's gone too far. Too many 
things are dynamic for the sake of it, and people are perhaps tempted to 
make too much use of that.

Although I do find Python's design interesting, from a language design 
and implementation point of view. It looks deceptively simple...

 > I know you have languages of your own, and that you like the way they
 > work better.  We have no way of evaluating their power or simplicity,
 > since they are not available to us.

My language, while simpler, has its own problems. And I don't want to 
get into support (I've done that in the past with other languages).

So at present, I'd probably still recommend Python, although there is 
also the similar Ruby and the smaller language Lua. There a few others 
but I haven't tried them.

 > We have no way of evaluating their power or simplicity,
 > since they are not available to us.

I'll see if I can rustle up a comparison so that Python users can see 
what they're missing!

-- 
Bartc


From steve at pearwood.info  Wed Nov 25 12:40:09 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 04:40:09 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <CAPTjJmomomPO6ujJjZtkSXM6Eeqo8_c7i-bpad24C2zveVU0kg@mail.gmail.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
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 <5654864E.2070906@rece.vub.ac.be>
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 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
Message-ID: <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>

On Wed, 25 Nov 2015 08:56 pm, Antoon Pardon wrote:

> Since (x, y, z) is not a fixed value, it is not a literal.

Right. And therefore, (x, y, z) syntax is not syntax for a literal. Hence
why the Python docs call it a tuple display instead of a tuple literal --
no matter what x, y, z are. Even if they themselves are literals, that's
just a special case that *some* compiler versions may be able to handle.

You call this "picking nits", but if so, they are nits that are twice the
size of an an elephant and painted bright yellow. Your language arguing
about "tuple literals" seems to be based on the idea that it is usually a
constant and that cases like (x+1, y+2) is some unusual, rare corner
case -- what you call "nits". Its not. The most general case is that a
tuple display is an expression which, after evaluation, constructs a tuple.
Those few cases where the compiler can optimize it into a constant are the
nits, not the majority of cases when it can't.

In fact, it's easy to find cases even now where the compiler is
insufficiently smart to recognise all the possible optimizations available.
There's no tuple simpler than the empty tuple, but Python 3.3 at least
fails to optimize that case:

py> dis(compile("()", '', 'eval'))
  1           0 BUILD_TUPLE              0
              3 RETURN_VALUE


The bottom line is, *in general*, the terms "tuple literal", "list
literal", "dict literal" etc. are inappropriate and incorrect, which is why
the docs correctly distinguish them from actual literals by calling
them "displays".



-- 
Steven



From ian.g.kelly at gmail.com  Wed Nov 25 12:44:35 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 10:44:35 -0700
Subject: list slice and generators
In-Reply-To: <n3418c$k41$1@ger.gmane.org>
References: <5654D8CE.2020105@gmail.com> <n3418c$k41$1@ger.gmane.org>
Message-ID: <CALwzidmnKPAY+X7tGxPreBXk2JiFnzVAJQ0q-erkcaR7MRtnvw@mail.gmail.com>

On Wed, Nov 25, 2015 at 3:07 AM, Peter Otten <__peter__ at web.de> wrote:
> to get down to one intermediate list. Avoiding the last one is a bit tricky:
>
> metrics = (converter(x.metric(name)) for x in self._server_per_proc)
> metrics = (x for x in metrics if x is not None)
> try:
>     # if there is at least one item the generator is not empty
>     first = next(metrics)
> except StopIteration:
>     metrics = ()
> else:
>     # put the first item back in
>     metrics = itertools.chain([first], metrics)
>     assert metrics

metrics is always going to be an itertools.chain object at this
assert, so how could the assertion ever fail?

>>     elif name in METRICS_AVG:
>           # writing a function that calculates the average without
>           # materialising the list left as an exercise ;)

        metrics = itertools.tee(metrics)
        return int(sum(metrics[0]) / len(metrics[1]))


From ian.g.kelly at gmail.com  Wed Nov 25 12:45:54 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 10:45:54 -0700
Subject: list slice and generators
In-Reply-To: <CALwzidmnKPAY+X7tGxPreBXk2JiFnzVAJQ0q-erkcaR7MRtnvw@mail.gmail.com>
References: <5654D8CE.2020105@gmail.com> <n3418c$k41$1@ger.gmane.org>
 <CALwzidmnKPAY+X7tGxPreBXk2JiFnzVAJQ0q-erkcaR7MRtnvw@mail.gmail.com>
Message-ID: <CALwzidnFXZEVt4OS2v59WHM_Pn=RbE4B6cDt1HMR5_KstUuzKA@mail.gmail.com>

On Wed, Nov 25, 2015 at 10:44 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Wed, Nov 25, 2015 at 3:07 AM, Peter Otten <__peter__ at web.de> wrote:
>>>     elif name in METRICS_AVG:
>>           # writing a function that calculates the average without
>>           # materialising the list left as an exercise ;)
>
>         metrics = itertools.tee(metrics)
>         return int(sum(metrics[0]) / len(metrics[1]))

Actually, don't do that. It does effectively materialize the list,
just not as a list.


From ian.g.kelly at gmail.com  Wed Nov 25 13:03:51 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 11:03:51 -0700
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n34qdc$sbp$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
Message-ID: <CALwzid=rqn1ANCuzaPqxpuDzaVTWw+eEeMJJbYiqcDn2K_DuLg@mail.gmail.com>

On Wed, Nov 25, 2015 at 10:18 AM, BartC <bc at freeuk.com> wrote:
>> We have no way of evaluating their power or simplicity,
>> since they are not available to us.
>
> I'll see if I can rustle up a comparison so that Python users can see what
> they're missing!

Unless you're going to make the actual languages available for public
use, what's the point?


From steve at pearwood.info  Wed Nov 25 13:09:13 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 05:09:13 +1100
Subject: Multiplication [was Re: Late-binding of function defaults]
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
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 <mailman.77.1448467192.20593.python-list@python.org>
Message-ID: <5655f94b$0$1583$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 02:59 am, Laura Creighton wrote:

> The great sticking point for the children I am teaching is
> '*' means multiplication.  You can really see that some people
> have to make extensive mental modifications in order to handle
> the concept that mathematical truths are expressed in linguistic
> and orthographic conventions, and that one can swap out a particular
> convention 'x means multiply' and swap in another one '* means
> multiply' while leaving the underlying truth unchanged.

Wow. What age children are you talking about?

I wasn't introduced to programming in any real depth until uni, after
graduating secondary school. I had lots of problems understanding bits of
it, and so did many of my fellow students, but * for multiplication wasn't
one of them.

But by this time, we had already learned in secondary school that you can
use any of the following to write multiplication:

x ? y
x ? y
x y

just as you can write division as:

x / y
x ? y

Adding * to the list of ways to write multiplication wasn't hard.

And I don't remember anyone having conceptual difficulty learning that xy is
a short-cut for x?y in maths class.


-- 
Steven



From __peter__ at web.de  Wed Nov 25 13:22:39 2015
From: __peter__ at web.de (Peter Otten)
Date: Wed, 25 Nov 2015 19:22:39 +0100
Subject: list slice and generators
References: <5654D8CE.2020105@gmail.com> <n3418c$k41$1@ger.gmane.org>
 <CALwzidmnKPAY+X7tGxPreBXk2JiFnzVAJQ0q-erkcaR7MRtnvw@mail.gmail.com>
Message-ID: <n34u9f$cd1$1@ger.gmane.org>

Ian Kelly wrote:

>>assert metrics
> 
> metrics is always going to be an itertools.chain object at this
> assert, so how could the assertion ever fail?

Should an assertion ever fail? 

>From your reaction I conclude that it was puzzling and a comment like

# always true in a boolean context

would have been the better choice. 


The problem I was half-heartedly addressing is that

>>>      if not metrics:
>>>         return None

"works" for empty lists but not for "empty" iterators. If it were my code 
I'd probably allow the average calculation to raise an exception and the sum 
to return 0, but there's always a limit to changing other people's code.




From __peter__ at web.de  Wed Nov 25 13:26:57 2015
From: __peter__ at web.de (Peter Otten)
Date: Wed, 25 Nov 2015 19:26:57 +0100
Subject: list slice and generators
References: <5654D8CE.2020105@gmail.com> <n3418c$k41$1@ger.gmane.org>
 <CALwzidmnKPAY+X7tGxPreBXk2JiFnzVAJQ0q-erkcaR7MRtnvw@mail.gmail.com>
 <CALwzidnFXZEVt4OS2v59WHM_Pn=RbE4B6cDt1HMR5_KstUuzKA@mail.gmail.com>
Message-ID: <n34uhh$gho$1@ger.gmane.org>

Ian Kelly wrote:

> On Wed, Nov 25, 2015 at 10:44 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>> On Wed, Nov 25, 2015 at 3:07 AM, Peter Otten <__peter__ at web.de> wrote:
>>>>     elif name in METRICS_AVG:
>>>           # writing a function that calculates the average without
>>>           # materialising the list left as an exercise ;)
>>
>>         metrics = itertools.tee(metrics)
>>         return int(sum(metrics[0]) / len(metrics[1]))
> 
> Actually, don't do that. It does effectively materialize the list,
> just not as a list.

Not just that, it will also complain

>>> a, b = itertools.tee([1,2,3])
>>> sum(a), len(b)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: object of type 'itertools._tee' has no len()




From antoon.pardon at rece.vub.ac.be  Wed Nov 25 13:27:56 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 19:27:56 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5655FDAC.4070305@rece.vub.ac.be>

Op 25-11-15 om 18:40 schreef Steven D'Aprano:
> On Wed, 25 Nov 2015 08:56 pm, Antoon Pardon wrote:
> 
>> Since (x, y, z) is not a fixed value, it is not a literal.
> 
> Right. And therefore, (x, y, z) syntax is not syntax for a literal. Hence
> why the Python docs call it a tuple display instead of a tuple literal --
> no matter what x, y, z are. Even if they themselves are literals, that's
> just a special case that *some* compiler versions may be able to handle.
> 
> You call this "picking nits", but if so, they are nits that are twice the
> size of an an elephant and painted bright yellow. Your language arguing
> about "tuple literals" seems to be based on the idea that it is usually a
> constant and that cases like (x+1, y+2) is some unusual, rare corner
> case -- what you call "nits".

I don't know what you are talking about. The first thing I have argued
is that () is a literal. Then I have expaned that to that something
like (3, 5, 8) is a literal. I never argued that tuple expressions
in general are literals. And one way I supported my point was with the
following quote from the python language reference.

  Literals are notations for constant values of some built-in types.

And I think that the things I argued were literals, were in fact
constant values of some built-in type.

> Its not. The most general case is that a
> tuple display is an expression which, after evaluation, constructs a tuple.
> Those few cases where the compiler can optimize it into a constant are the
> nits, not the majority of cases when it can't.

The nits, depend on what someone tries to argue. Since I didn't try
to argue that tuple displays in general are literals but argued
for very specific tuple values to be literals, you starting
about tuple displays is going of on a tangent that has little
to do with what I was arguing.

-- 
Antoon


From harvest at should.be.invalid  Wed Nov 25 13:30:07 2015
From: harvest at should.be.invalid (Jussi Piitulainen)
Date: Wed, 25 Nov 2015 20:30:07 +0200
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <mailman.429.1447884751.16136.python-list@python.org>
 <n2j0k4$up4$1@dont-email.me>
 <CAPTjJmq7gsDDo10aQnb1VuM9boSBsncL9sgvz6+w+pcVeHsDCA@mail.gmail.com>
 <56544BAB.9020709@rece.vub.ac.be>
 <CAPTjJmrRzvDx1xqe3DxRCNgfQn4x5R8Z_0UCyqbonLYsNY42NA@mail.gmail.com>
 <mailman.110.1448369310.2291.python-list@python.org>
 <874mgbpnb5.fsf@elektro.pacujo.net>
 <486929d1-4caa-403c-89e6-c45d7b447f98@googlegroups.com>
 <5655035c$0$1609$c3e8da3$5496439d@news.astraweb.com>
 <201511250055.tAP0tpfO005889@fido.openend.se>
 <mailman.62.1448444207.20593.python-list@python.org>
 <lf5a8q2xq7z.fsf@ling.helsinki.fi> <87egfent2i.fsf@elektro.pacujo.net>
 <lf54mgaxgbh.fsf@ling.helsinki.fi> <877fl66nb9.fsf@elektro.pacujo.net>
Message-ID: <lf5wpt6vsnk.fsf@ling.helsinki.fi>

Marko Rauhamaa writes:
> Jussi Piitulainen writes:
>
>> You know, people have developed further ways to talk about these
>> things precisely because substitution semantics is inadequate for
>> what they wanted to talk about.
>
> "Assignment" is what everybody uses and understands.

You can tell that to those who insist otherwise, and to those who
understand it differently, and to those who are just confused.
All are around in this thread.

But yes, I would find it easier if variables could be called variables,
assignment could be called assignment, and binding could be called
binding even in Python (variations of the last one somewhat work; the
former two are problematic in the way that any mention of regular
expressions is, whether you've noticed it or not).

>> Not substituted to the program text - who would even think that?
>
> Actually, if Scheme didn't possess set! et al, we would be talking
> about true binding. For example, the function
>
>    (define (sum numbers)
>      (let loop ((total 0) (remaining numbers))
>        (if (null? remaining)
>            total
>            (loop (+ total (car remaining)) (cdr remaining)))))
>
> can be described and effectively implemented using true, syntactic
> binding. To execute such code, you start with an expression, say,
> (sum '(1 2 3 4 5)) and keep on rewriting the expression until you can't
> rewrite it anymore.

Interesting. Can you just keep reducing / expanding the expression
without reference to an environment? I see how it's easy to talk about
assignment because one can talk about something else, but I'm not yet
quite sure how you intend to handle recursion.

==> (let loop ((total 0) (remaining '(1 2 3 4 5)))
       (if (null? remaining)
           total
           (loop (+ total (car remaining)) (cdr remaining))))

Now what? Rewrite using a call-by-value fixed-point operator and keep
insisting that you just saw a squirrel? Or rewrite with respect to an
environment where loop is bound to a lambda expression that is closed in
that same environment and this is somehow true substitution and you just
saw a squirrel? Link to a Wikipedia page that tells what call-by-value
and call-by-reference are and remind me that one should really talk
about passing a reference by value?

That last one is as irrelevant as squirrels, by the way.

> The availability of set! forces the implementation to generate a
> memory slot for each binding, turning the binding semantics into an
> assignment semantics.

Thank you.

I'm probably out now.


From lac at openend.se  Wed Nov 25 13:45:10 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 25 Nov 2015 19:45:10 +0100
Subject: Multiplication [was Re: Late-binding of function defaults]
In-Reply-To: <5655f94b$0$1583$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <mailman.77.1448467192.20593.python-list@python.org>
 <5655f94b$0$1583$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <201511251845.tAPIjAde022935@fido.openend.se>

In a message of Thu, 26 Nov 2015 05:09:13 +1100, "Steven D'Aprano" writes:
>On Thu, 26 Nov 2015 02:59 am, Laura Creighton wrote:
>
>> The great sticking point for the children I am teaching is
>> '*' means multiplication.  You can really see that some people
>> have to make extensive mental modifications in order to handle
>> the concept that mathematical truths are expressed in linguistic
>> and orthographic conventions, and that one can swap out a particular
>> convention 'x means multiply' and swap in another one '* means
>> multiply' while leaving the underlying truth unchanged.
>
>Wow. What age children are you talking about?

12 and 13 and 14 year olds. Smart 12, 13 and 14 year olds.

They want to build web servers and host pictures of their pets.
and use the gimp to do image manipulation like crazy. They are
as interested in art as much as, or perhaps even more so than
in programming -- they just need to learn enough programming to
get to make the art and serve it up.

Designing your own Magic The Gathering cards, which has manipulated
pictures of your friends on them, and then using them to play games 
with said friends has been the craze since September.

It's not that the idea of we will use '*' is hard, but if you have
never thought about the difference between THE TRUTH and the notation
used to express the truth before, then well, you may need some time
to get used to the idea.

Laura




From bc at freeuk.com  Wed Nov 25 13:48:44 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 18:48:44 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.82.1448474673.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.82.1448474673.20593.python-list@python.org>
Message-ID: <n34vm4$jq8$1@dont-email.me>

On 25/11/2015 18:03, Ian Kelly wrote:
> On Wed, Nov 25, 2015 at 10:18 AM, BartC <bc at freeuk.com> wrote:
>>> We have no way of evaluating their power or simplicity,
>>> since they are not available to us.
>>
>> I'll see if I can rustle up a comparison so that Python users can see what
>> they're missing!
>
> Unless you're going to make the actual languages available for public
> use, what's the point?

For ideas? Sometimes it's interesting to know about other approaches to 
a feature or new ones that can be useful.

Then someone else can implement them! I'd be sharing my language design 
ideas not my amateurish implementations.

(Which aren't easy to distribute anyway because they are implemented in 
themselves.)

-- 
Bartc






From emile at fenx.com  Wed Nov 25 13:51:12 2015
From: emile at fenx.com (Emile van Sebille)
Date: Wed, 25 Nov 2015 10:51:12 -0800
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <5655A8B3.6000103@rece.vub.ac.be>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <5655A8B3.6000103@rece.vub.ac.be>
Message-ID: <n34vv1$7dk$1@ger.gmane.org>

On 11/25/2015 4:25 AM, Antoon Pardon wrote:

> I think there are reasons to find the above behaviour bizarre. I personnaly
> don't find it bizarre, but that is because I'm familiar with what is going
> on.

Which I suspect is necessary.

 >but if someone expects the compilor to take a snapshot of L and iterate
> over that I am not going to say he shouldn't have expected that.

That's something I've learned to figure out about any new language I 
pick up -- if parameters are passed by value or by reference, and 
secondly how to invoke a function appropriately for my specific use case.

Unfortunately, there are issues determining if python is in either camp, 
which certainly leads to confusion. see 
http://www.python-course.eu/passing_arguments.php or google "python pass 
by value or reference" for more examples.

Emile



From emile at fenx.com  Wed Nov 25 13:56:43 2015
From: emile at fenx.com (Emile van Sebille)
Date: Wed, 25 Nov 2015 10:56:43 -0800
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n34cem$4l5$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
Message-ID: <n3509b$d0n$1@ger.gmane.org>

On 11/25/2015 5:20 AM, BartC wrote:

> it seems to be more lucrative to write thicker user manuals, and provide
> longer training courses, than to make software simpler.

If that were true, certainly by now the sufficiently thick manual would 
provide crystal clear explanations.  :)

I-don't-think-obfustication-is-the-point-ly y'rs,

Emile




From ben+python at benfinney.id.au  Wed Nov 25 14:55:24 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 26 Nov 2015 06:55:24 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <CAPTjJmoyGi04Dnxxp1AFytLkWQg=D4ccXqE6OwfJJMgp7fg1YA@mail.gmail.com>
Message-ID: <858u5lc0r7.fsf@benfinney.id.au>

Chris Angelico <rosuav at gmail.com> writes:

> This is a distinction I generally make. Putting it another way: a list
> has the same meaning regardless of how many items are on it (for
> instance, a shopping list is still a shopping list whether it has five
> or fifty items on it), where a tuple is a package where each element
> has a specific meaning [?]

Yes. The disctinction is even clearer, I find, by saying that the
*meaning of the position* in the sequence is significant for a tuple,
not significant for a list.

That is, the ?2? in ?cartesian_point = (2, 3)? means something different
than in ?cartesian_point = (3, 2)?.

Whereas the ?2? in ?test_scores = [2, 3]? means exactly the same as in
?test_scores = [3, 2]?.

If each position in the sequence gives the value there a different
menaning, use a tuple; if not, use a list.

> Nothing in the language enforces this, but the mutability of lists
> does tend to align well with things that can grow and shrink, and the
> immutability of tuples makes them more like strings or complex numbers
> (in fact, a complex number is basically a tuple of two floats).

Not only the growing and shrinking, but the re-ordering of items in a
list should not change the meaning of its items.

If you can ?sort? the sequence and the items still mean exactly what
they did before, then a tuple is the wrong type to use, semantically.

-- 
 \       ?Crime is contagious? if the government becomes a lawbreaker, |
  `\          it breeds contempt for the law.? ?Justice Louis Brandeis |
_o__)                                                                  |
Ben Finney



From ben+python at benfinney.id.au  Wed Nov 25 14:57:17 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 26 Nov 2015 06:57:17 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <201511251559.tAPFxVm6020346@fido.openend.se>
Message-ID: <854mg9c0o2.fsf@benfinney.id.au>

Laura Creighton <lac at openend.se> writes:

> The great sticking point for the children I am teaching is '*' means
> multiplication. [?] that one can swap out a particular convention 'x
> means multiply' and swap in another one '* means multiply' while
> leaving the underlying truth unchanged.

Perhaps it would be easier if you point out that ?x? doesn't mean
multiply either, and they've *already* been substituting that symbol
instead of the correct ??? for multiply.

-- 
 \     ?Our task must be to free ourselves from our prison by widening |
  `\    our circle of compassion to embrace all humanity and the whole |
_o__)                       of nature in its beauty.? ?Albert Einstein |
Ben Finney



From Cecil at decebal.nl  Wed Nov 25 15:23:05 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Wed, 25 Nov 2015 21:23:05 +0100
Subject: Help needed with compiling python
Message-ID: <877fl596c6.fsf@Equus.decebal.nl>

I wanted to install python myself. I started with 2.7.10. If that
works I also will install 3.5.0.

I did:
    ./configure --prefix=/usr
    make
    make altinstall

I have:
    /usr/bin/python2.7

But when I execute this, I get:
    Could not find platform dependent libraries <exec_prefix>
    Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
    Python 2.7.10 (default, Nov 25 2015, 20:58:29) 
    [GCC 4.8.5] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    Traceback (most recent call last):
      File "/etc/pythonstart", line 7, in <module>
        import readline
    ImportError: No module named readline

What do I need to do to get it working?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From francisfunari at hotmail.com  Wed Nov 25 15:34:01 2015
From: francisfunari at hotmail.com (francis funari)
Date: Wed, 25 Nov 2015 20:34:01 +0000
Subject: Python on windows 10 
Message-ID: <CY1PR13MB0809508315283B56278491A7AA050@CY1PR13MB0809.namprd13.prod.outlook.com>

I have tried installing Python 3 on windows 10 it install OK but I do not get Idle. When I type Idle in the interpreter nothing happen can you send me a link to latest release of Python 3 with Idle that will run on windows 10 64 bit
                                                                                                              Thankyou Francis Funari

Sent from Mail<http://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From ian.g.kelly at gmail.com  Wed Nov 25 15:39:44 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 13:39:44 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <5655FDAC.4070305@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <5655FDAC.4070305@rece.vub.ac.be>
Message-ID: <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>

On Wed, Nov 25, 2015 at 11:27 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> I don't know what you are talking about. The first thing I have argued
> is that () is a literal. Then I have expaned that to that something
> like (3, 5, 8) is a literal. I never argued that tuple expressions
> in general are literals. And one way I supported my point was with the
> following quote from the python language reference.
>
>   Literals are notations for constant values of some built-in types.
>
> And I think that the things I argued were literals, were in fact
> constant values of some built-in type.

I believe that sentence from the docs is using "some" to mean "not
all", whereas you are apparently using it to mean "any".

frozenset([1,2,3]) constructs a constant value of a built-in type.
Would you consider that a literal?

How about tuple(1, 2+3, abs(-19))? Still a constant value of a built-in type.

I think the most important word in the definition you quoted is
actually "notation". It says it right there: literals are not
"constant values", but notations for *expressing* constant values.

The tuple display notation expresses values that may be constant but
need not be. Therefore it's not a literal notation.


From ryanshuell at gmail.com  Wed Nov 25 15:42:00 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 25 Nov 2015 12:42:00 -0800 (PST)
Subject: Screen scraper to get all 'a title' elements
Message-ID: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>

Hello experts.  I'm looking at this url:
https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names

I'm trying to figure out how to list all 'a title' elements.  For instance, I see the following:
<a title="Accident, Maryland" href="/wiki/Accident,_Maryland">Accident</a>
<a class="new" title="Ala-Lemu (page does not exist)" href="/w/index.php?title=Ala-Lemu&action=edit&redlink=1">Ala-Lemu</a>
<a title="Alert, Nunavut" href="/wiki/Alert,_Nunavut">Alert</a>
<a title="Apocalypse Peaks" href="/wiki/Apocalypse_Peaks">Apocalypse Peaks</a>

So, I tried putting a script together to get 'title'.  Here's my attempt.

import requests
import sys
from bs4 import BeautifulSoup

url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"     
source_code = requests.get(url) 
plain_text = source_code.text
soup = BeautifulSoup(plain_text)
for link in soup.findAll('title'):
    print(link)

All that does is get the title of the page.  I tried to get the links from that url, with this script.

import urllib2
import re

#connect to a URL
website = urllib2.urlopen('https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names')

#read html code
html = website.read()

#use re.findall to get all the links
links = re.findall('"((http|ftp)s?://.*?)"', html)

print links

That doesn't work wither.  Basically, I'd like to see this.

Accident
Ala-Lemu
Alert
Apocalypse Peaks
Athol
?
Barbecue
B?stad
Bastardstown
Batman
Bathmen (Battem), Netherlands
...
Worms
Yell
Zigzag
Zzyzx

How can I do that?
Thanks all!!




From pavlos.parissis at gmail.com  Wed Nov 25 15:43:20 2015
From: pavlos.parissis at gmail.com (Pavlos Parissis)
Date: Wed, 25 Nov 2015 21:43:20 +0100
Subject: list slice and generators
In-Reply-To: <n3418c$k41$1@ger.gmane.org>
References: <5654D8CE.2020105@gmail.com> <n3418c$k41$1@ger.gmane.org>
Message-ID: <56561D68.9080901@gmail.com>

On 25/11/2015 11:07 ??, Peter Otten wrote:
> Pavlos Parissis wrote:
> 
>> Hi,
>>
>> Do you see any possible dangerous hidden bug in the below code(using
>> python2.7 and python3.4)?
>>
>> My goal is to avoid go through the metrics list twice. But, I don't
>> know if there will be a problem with doing in place replace of list
>> elements using 2 generators.
>>
>> # metrics = ['', '0', '10'....]
>> metrics = [x.metric(name) for x in self._server_per_proc]
>> metrics[:] = (converter(x) for x in metrics)
>> metrics[:] = (x for x in metrics if x is not None)
> 
> Both generators are executed immediately, and the right side is always 
> evaluated before the the slice assignment. Try
> 

This is what I was vaguely remembering, thanks for the confirmation.

> metrics = (x.metric(name) for x in self._server_per_proc)
> metrics = (converter(x) for x in metrics)
> metrics = [x for x in metrics if x is not None]
> 

I see you prefer to bind the result of the evaluation to the same
variable. I learned (the hard way) that it could lead to problems where::

In [1]: a = [1, 2, 3]

In [2]: b = a

In [3]: a == b, a is b
Out[3]: (True, True)

In [4]: a = (x for x in a if x >1)

In [5]: a == b, a is b
Out[5]: (False, False)

In [6]: a
Out[6]: <generator object <genexpr> at 0x7f7f8b7400d8>

In [7]: list(a)
Out[7]: [2, 3]

In [8]: a = [1, 2, 3]

In [9]: b = a

In [10]: a == b, a is b
Out[10]: (True, True)

In [11]: a = [x for x in a if x >1]

In [12]: a == b, a is b
Out[12]: (False, False)

In [13]: a
Out[13]: [2, 3]

In [14]: b
Out[14]: [1, 2, 3]

Thus, I always use slice assignment, even when above case isn't applied.

> or
> 
> metrics = (converter(x.metric(name)) for x in self._server_per_proc)
> metrics = [x for x in metrics if x is not None]
> 

I should do the above.

> to get down to one intermediate list. Avoiding the last one is a bit tricky:
> 
> metrics = (converter(x.metric(name)) for x in self._server_per_proc)
> metrics = (x for x in metrics if x is not None)
> try:
>     # if there is at least one item the generator is not empty
>     first = next(metrics)
> except StopIteration:
>     metrics = ()
> else:
>     # put the first item back in
>     metrics = itertools.chain([first], metrics)
>     assert metrics
> 

Tricky, indeed

Thanks for your time and effort to answer my question, it is very
much appreciated.

Cheers,
Pavlos

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From zachary.ware+pylist at gmail.com  Wed Nov 25 15:49:16 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 25 Nov 2015 14:49:16 -0600
Subject: Help needed with compiling python
In-Reply-To: <877fl596c6.fsf@Equus.decebal.nl>
References: <877fl596c6.fsf@Equus.decebal.nl>
Message-ID: <CAKJDb-NyiQtpPQDg+2=Fch8cqvFx24QVox3+1ksTzqA5qAUBfg@mail.gmail.com>

On Wed, Nov 25, 2015 at 2:23 PM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> I wanted to install python myself. I started with 2.7.10. If that
> works I also will install 3.5.0.
>
> I did:
>     ./configure --prefix=/usr
>     make
>     make altinstall
>
> I have:
>     /usr/bin/python2.7
>
> But when I execute this, I get:
>     Could not find platform dependent libraries <exec_prefix>
>     Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
>     Python 2.7.10 (default, Nov 25 2015, 20:58:29)
>     [GCC 4.8.5] on linux2
>     Type "help", "copyright", "credits" or "license" for more information.
>     Traceback (most recent call last):
>       File "/etc/pythonstart", line 7, in <module>
>         import readline
>     ImportError: No module named readline
>
> What do I need to do to get it working?

First off, I strongly suggest not using --prefix=/usr.  Stick with
--prefix=/usr/local (the default) to avoid overwriting the system
Python, which may differ from a source build (and, in fact,
overwriting your system Python may be what's causing some of your
problems; those first two lines are worrying).

Secondly, there are several optional modules that are not compiled
unless particular libraries are found to link against, including
readline.  You'll need the readline development package (probably
readline-dev or readline-devel, depending on your distribution).  You
can quickly pull in the dependencies for all optional modules by doing
something like the following for an apt-based system: `apt-get
build-dep python3`.

Hope this helps,
-- 
Zach


From breamoreboy at yahoo.co.uk  Wed Nov 25 15:50:38 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Wed, 25 Nov 2015 20:50:38 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n34qdc$sbp$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
Message-ID: <n356v2$thh$1@ger.gmane.org>

On 25/11/2015 17:18, BartC wrote:
> On 25/11/2015 15:13, Ned Batchelder wrote:
>> On Wednesday, November 25, 2015 at 8:20:59 AM UTC-5, BartC wrote:
>>> Accept that some things /are/ a source of confusion. When, in writing
>>> documentation, I find something hard to explain something, then I try
>>> and make it simpler in the program. But not enough of that goes on: it
>>> seems to be more lucrative to write thicker user manuals, and provide
>>> longer training courses, than to make software simpler.
>>
>> You seem to be insinuating that someone has made Python unusually complex
>> for personal gain?  I'm not sure what to do with that: it's an absurd
>> claim.
>
> Actually I was thinking of certain Microsoft products. But I think my
> point stands: the design of software could be influenced more by the
> documentation. In the case of languages, that's perhaps harder because
> languages tend to evolve, and they usually have to be backwards compatible.
>
>>>> "Why does the loop run forever?"
>>>>
>>>> The coin doesn't magically toss itself, no matter how intuitively
>>>> obvious it
>>>> is that it should.
>>>
>>> The concept of variables doesn't take long to learn in an 'ordinary'
>>> language.
>
>> There is a natural tension between making a language simple enough that
>> it has no surprises or difficult parts; and making a language rich
>> enough that it can be used for building serious systems.
>
> Well, with Python I get the impression it's gone too far. Too many
> things are dynamic for the sake of it, and people are perhaps tempted to
> make too much use of that.
>
> Although I do find Python's design interesting, from a language design
> and implementation point of view. It looks deceptively simple...
>
>  > I know you have languages of your own, and that you like the way they
>  > work better.  We have no way of evaluating their power or simplicity,
>  > since they are not available to us.
>
> My language, while simpler, has its own problems. And I don't want to
> get into support (I've done that in the past with other languages).
>
> So at present, I'd probably still recommend Python, although there is
> also the similar Ruby and the smaller language Lua. There a few others
> but I haven't tried them.
>
>  > We have no way of evaluating their power or simplicity,
>  > since they are not available to us.
>
> I'll see if I can rustle up a comparison so that Python users can see
> what they're missing!
>

Can you please let us know what you're taking, what it costs and where 
we can get it, as we would also like to live in cloud cuckoo land, 
provided that The Price Is Right?.

Although credit where credit is due, you are one of the most successful 
trolls to con this list in years.  I must offer my congratulations.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From clalancette at gmail.com  Wed Nov 25 15:52:25 2015
From: clalancette at gmail.com (Chris Lalancette)
Date: Wed, 25 Nov 2015 15:52:25 -0500
Subject: Looking for ideas to improve library API
Message-ID: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>

Hello,
     I'm currently developing a library called pyiso (
https://github.com/clalancette/pyiso), used for manipulating ISO disk
images.  I'm pretty far along with it, but there is one part of the API
that I really don't like.
    Typical usage of the library is something like:

import pyiso

p = pyiso.PyIso() // create the object
f = open('/path/to/original.iso', 'r')
p.open(f)  // parse all of the metadata from the input ISO
fp = open('/path/to/file/to/add/to/iso', 'r')
p.add_fp(fp)  // add a new file to the ISO
out = open('/path/to/modified.iso', 'w')
p.write(out)  // write out the modified ISO to another file
out.close()
fp.close()
f.close()

This currently works OK.  The problem ends up being the file descriptor
lifetimes.  I want the user to be able to do multiple operations to the
ISO, and I also don't want to read the entire ISO (and new files) into
memory.  That means that internal to the library, I take a reference to the
file object that the user passes in during open() and add_fp().  This is
fine, unless the user decides to close the file object before calling the
write method, at which point the write complains of I/O to a closed file.
This is especially problematic when it comes to using context managers,
since the user needs to leave the context open until they call write().
      I've thought of a couple ways to deal with this:

1.  Make a copy of the file object internal to the library, using os.dup()
to copy the file descriptor.  This is kind of nasty, especially since I
want to support other kinds of file objects (think StringIO).
2.  Just document the fact that the user needs to leave the file objects
open until they are done.  This is simple, but not super user-friendly.

I'm looking for any ideas of how to do this better, or something I missed.
Any input is appreciated!

Thanks,
Chris Lalancette


From python at mrabarnett.plus.com  Wed Nov 25 15:55:56 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Wed, 25 Nov 2015 20:55:56 +0000
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
Message-ID: <5656205C.1030804@mrabarnett.plus.com>

On 2015-11-25 20:42, ryguy7272 wrote:
> Hello experts.  I'm looking at this url:
> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
>
> I'm trying to figure out how to list all 'a title' elements.  For instance, I see the following:
> <a title="Accident, Maryland" href="/wiki/Accident,_Maryland">Accident</a>
> <a class="new" title="Ala-Lemu (page does not exist)" href="/w/index.php?title=Ala-Lemu&action=edit&redlink=1">Ala-Lemu</a>
> <a title="Alert, Nunavut" href="/wiki/Alert,_Nunavut">Alert</a>
> <a title="Apocalypse Peaks" href="/wiki/Apocalypse_Peaks">Apocalypse Peaks</a>
>
> So, I tried putting a script together to get 'title'.  Here's my attempt.
>
> import requests
> import sys
> from bs4 import BeautifulSoup
>
> url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
> source_code = requests.get(url)
> plain_text = source_code.text
> soup = BeautifulSoup(plain_text)
> for link in soup.findAll('title'):
>      print(link)
>
> All that does is get the title of the page.  I tried to get the links from that url, with this script.
>
A 'title' element has the form "<title ...>". What you should be looking 
for are 'a' elements, those of the form "<a ...>".

> import urllib2
> import re
>
> #connect to a URL
> website = urllib2.urlopen('https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names')
>
> #read html code
> html = website.read()
>
> #use re.findall to get all the links
> links = re.findall('"((http|ftp)s?://.*?)"', html)
>
> print links
>
> That doesn't work wither.  Basically, I'd like to see this.
>
> Accident
> Ala-Lemu
> Alert
> Apocalypse Peaks
> Athol
> ?
> Barbecue
> B?stad
> Bastardstown
> Batman
> Bathmen (Battem), Netherlands
> ...
> Worms
> Yell
> Zigzag
> Zzyzx
>
> How can I do that?
> Thanks all!!
>
>



From marko at pacujo.net  Wed Nov 25 16:00:55 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 23:00:55 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <201511251559.tAPFxVm6020346@fido.openend.se>
 <mailman.91.1448481614.20593.python-list@python.org>
Message-ID: <877fl56bg8.fsf@elektro.pacujo.net>

Ben Finney <ben+python at benfinney.id.au>:

> Perhaps it would be easier if you point out that ?x? doesn't mean
> multiply either, and they've *already* been substituting that symbol
> instead of the correct ??? for multiply.

In my childhood, we always used '?' for the multiplication sign until
senior high school, when the vector product was introduced.

I seem to recall ??? was used in cartesian products already in junior
high.


Marko


From marko at pacujo.net  Wed Nov 25 16:04:55 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Wed, 25 Nov 2015 23:04:55 +0200
Subject: Multiplication [was Re: Late-binding of function defaults]
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <mailman.77.1448467192.20593.python-list@python.org>
 <5655f94b$0$1583$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <8737vt6b9k.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> But by this time, we had already learned in secondary school that you can
> use any of the following to write multiplication:
>
> x ? y

Not where I lived. (Those x's would have been a nightmare for the
teacher who had to mark people's test answers.)

> x ? y

Yes. After all, it would never get mixed up with the decimal comma.

> x y

Not to multiply numbers with each other.

> just as you can write division as:
>
> x / y

Not where I lived.

> x ? y

Not that one, either.

               x
We only had:  ---
               y


Marko


From antoon.pardon at rece.vub.ac.be  Wed Nov 25 16:05:30 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Wed, 25 Nov 2015 22:05:30 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <5655FDAC.4070305@rece.vub.ac.be>
 <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>
Message-ID: <5656229A.2000309@rece.vub.ac.be>

Op 25-11-15 om 21:39 schreef Ian Kelly:
> On Wed, Nov 25, 2015 at 11:27 AM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> I don't know what you are talking about. The first thing I have argued
>> is that () is a literal. Then I have expaned that to that something
>> like (3, 5, 8) is a literal. I never argued that tuple expressions
>> in general are literals. And one way I supported my point was with the
>> following quote from the python language reference.
>>
>>   Literals are notations for constant values of some built-in types.
>>
>> And I think that the things I argued were literals, were in fact
>> constant values of some built-in type.
> 
> I believe that sentence from the docs is using "some" to mean "not
> all", whereas you are apparently using it to mean "any".
> 
> frozenset([1,2,3]) constructs a constant value of a built-in type.
> Would you consider that a literal?

I am inclined to say yes, because a sufficient intelligent compilor
can compute the value and store it do be retrieved and bound to a
target when needed.

> How about tuple(1, 2+3, abs(-19))? Still a constant value of a built-in type.

Same reasoning.

> I think the most important word in the definition you quoted is
> actually "notation". It says it right there: literals are not
> "constant values", but notations for *expressing* constant values.

And how does that make a difference?

> The tuple display notation expresses values that may be constant but
> need not be. Therefore it's not a literal notation.

Not in general no. It doesn't imply that not any tuple display notation
is a literal notation.

Expression may be constant but need not be, that is no reason to claim
that anything that is an expression can't be a literal.

-- 
Antoon.


From Cecil at decebal.nl  Wed Nov 25 16:52:23 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Wed, 25 Nov 2015 22:52:23 +0100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
Message-ID: <8737vt927c.fsf@Equus.decebal.nl>

On Wednesday 25 Nov 2015 21:49 CET, Zachary Ware wrote:

> On Wed, Nov 25, 2015 at 2:23 PM, Cecil Westerhof <Cecil at decebal.nl> wrote:
>> I wanted to install python myself. I started with 2.7.10. If that
>> works I also will install 3.5.0.
>>
>> I did:
>> ./configure --prefix=/usr
>> make
>> make altinstall
>>
>> I have:
>> /usr/bin/python2.7
>>
>> But when I execute this, I get: Could not find platform dependent
>> libraries <exec_prefix> Consider setting $PYTHONHOME to
>> <prefix>[:<exec_prefix>] Python 2.7.10 (default, Nov 25 2015,
>> 20:58:29) [GCC 4.8.5] on linux2 Type "help", "copyright", "credits"
>> or "license" for more information. Traceback (most recent call
>> last): File "/etc/pythonstart", line 7, in <module> import readline
>> ImportError: No module named readline
>>
>> What do I need to do to get it working?
>
> First off, I strongly suggest not using --prefix=/usr.  Stick with
> --prefix=/usr/local (the default) to avoid overwriting the system
> Python, which may differ from a source build (and, in fact,
> overwriting your system Python may be what's causing some of your
> problems; those first two lines are worrying).

My system python was all-ready damaged: that is why I wanted to build
myself.


> Secondly, there are several optional modules that are not compiled
> unless particular libraries are found to link against, including
> readline. You'll need the readline development package (probably
> readline-dev or readline-devel, depending on your distribution). You
> can quickly pull in the dependencies for all optional modules by
> doing something like the following for an apt-based system: `apt-get
> build-dep python3`.

It is an openSUSE system. I installed the readline with:
    zypper install readline-devel

The strange thing is that it does mot compile anymore now. I get:
Python build finished, but the necessary bits to build these modules were not found:
    _bsddb             _tkinter           bsddb185        
    dbm                dl                 gdbm            
    imageop            sunaudiodev                        
    To find the necessary bits, look in setup.py in detect_modules() for the module's name.

I have to look into that.

I still can install it, but get the same errors.

I think I need a bit more time to solve it.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From bc at freeuk.com  Wed Nov 25 16:56:39 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 21:56:39 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.95.1448484677.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
Message-ID: <n35amf$21o$1@dont-email.me>

On 25/11/2015 20:50, Mark Lawrence wrote:
> On 25/11/2015 17:18, BartC wrote:

> Can you please let us know what you're taking, what it costs and where
> we can get it, as we would also like to live in cloud cuckoo land,
> provided that The Price Is Right?.

And I would really like to know what your problem is.

I'm interested in language design because that's what I've done on and 
off for over 30 years. And I'm discussing some design decisions in Python.

> Although credit where credit is due, you are one of the most successful
> trolls to con this list in years.  I must offer my congratulations.

If you think I'm a 'troll' then that's your business. But I'm not 
holding a gun to your head and forcing you to read my posts.



From ryanshuell at gmail.com  Wed Nov 25 17:04:08 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 25 Nov 2015 14:04:08 -0800 (PST)
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
Message-ID: <a6f3a0a7-acc3-46db-a36b-c3d774293347@googlegroups.com>

On Wednesday, November 25, 2015 at 3:42:21 PM UTC-5, ryguy7272 wrote:
> Hello experts.  I'm looking at this url:
> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
> 
> I'm trying to figure out how to list all 'a title' elements.  For instance, I see the following:
> <a title="Accident, Maryland" href="/wiki/Accident,_Maryland">Accident</a>
> <a class="new" title="Ala-Lemu (page does not exist)" href="/w/index.php?title=Ala-Lemu&action=edit&redlink=1">Ala-Lemu</a>
> <a title="Alert, Nunavut" href="/wiki/Alert,_Nunavut">Alert</a>
> <a title="Apocalypse Peaks" href="/wiki/Apocalypse_Peaks">Apocalypse Peaks</a>
> 
> So, I tried putting a script together to get 'title'.  Here's my attempt.
> 
> import requests
> import sys
> from bs4 import BeautifulSoup
> 
> url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"     
> source_code = requests.get(url) 
> plain_text = source_code.text
> soup = BeautifulSoup(plain_text)
> for link in soup.findAll('title'):
>     print(link)
> 
> All that does is get the title of the page.  I tried to get the links from that url, with this script.
> 
> import urllib2
> import re
> 
> #connect to a URL
> website = urllib2.urlopen('https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names')
> 
> #read html code
> html = website.read()
> 
> #use re.findall to get all the links
> links = re.findall('"((http|ftp)s?://.*?)"', html)
> 
> print links
> 
> That doesn't work wither.  Basically, I'd like to see this.
> 
> Accident
> Ala-Lemu
> Alert
> Apocalypse Peaks
> Athol
> ?
> Barbecue
> B?stad
> Bastardstown
> Batman
> Bathmen (Battem), Netherlands
> ...
> Worms
> Yell
> Zigzag
> Zzyzx
> 
> How can I do that?
> Thanks all!!



Ok, I guess that makes sense.  So, I just tried the script below, and got nothing...

import requests
from bs4 import BeautifulSoup

r = requests.get("https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names")
soup = BeautifulSoup(r.content)
print soup.find_all("a",{"title"})


From rosuav at gmail.com  Wed Nov 25 17:06:26 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 09:06:26 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <5656229A.2000309@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <5655FDAC.4070305@rece.vub.ac.be>
 <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>
 <5656229A.2000309@rece.vub.ac.be>
Message-ID: <CAPTjJmpc+upayXctBei4ZC04vfgPQSpY0RfvG7jv-n4npViHBg@mail.gmail.com>

On Thu, Nov 26, 2015 at 8:05 AM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 25-11-15 om 21:39 schreef Ian Kelly:
>> On Wed, Nov 25, 2015 at 11:27 AM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>> I don't know what you are talking about. The first thing I have argued
>>> is that () is a literal. Then I have expaned that to that something
>>> like (3, 5, 8) is a literal. I never argued that tuple expressions
>>> in general are literals. And one way I supported my point was with the
>>> following quote from the python language reference.
>>>
>>>   Literals are notations for constant values of some built-in types.
>>>
>>> And I think that the things I argued were literals, were in fact
>>> constant values of some built-in type.
>>
>> I believe that sentence from the docs is using "some" to mean "not
>> all", whereas you are apparently using it to mean "any".
>>
>> frozenset([1,2,3]) constructs a constant value of a built-in type.
>> Would you consider that a literal?
>
> I am inclined to say yes, because a sufficient intelligent compilor
> can compute the value and store it do be retrieved and bound to a
> target when needed.

Then you're using the word "literal" in a way that is flat wrong. It
may be a constant, but it is not a literal.

ChrisA


From rosuav at gmail.com  Wed Nov 25 17:10:43 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 09:10:43 +1100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <a6f3a0a7-acc3-46db-a36b-c3d774293347@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <a6f3a0a7-acc3-46db-a36b-c3d774293347@googlegroups.com>
Message-ID: <CAPTjJmqTJ5f_WPZZM-gC3=iCCVOMHStmS8MKb3o_G29dwF4yBg@mail.gmail.com>

On Thu, Nov 26, 2015 at 9:04 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
> Ok, I guess that makes sense.  So, I just tried the script below, and got nothing...
>
> import requests
> from bs4 import BeautifulSoup
>
> r = requests.get("https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names")
> soup = BeautifulSoup(r.content)
> print soup.find_all("a",{"title"})

The second argument to find_all is supposed to be a dict, not a set,
and it's only useful if you want to put some restriction on the
titles. To simply enumerate all the titles, try this:

[a.get("title") for a in soup.find_all("a")]

ChrisA


From marko at pacujo.net  Wed Nov 25 17:16:32 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 00:16:32 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me>
Message-ID: <87k2p54tdr.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> I'm interested in language design because that's what I've done on and
> off for over 30 years. And I'm discussing some design decisions in
> Python.

That *is* a fun ambition, useful or not.

However, while I'm very choosy and critical when it comes to my
programming tools, I'm extremely happy with the programming language
options that are freely available. It would be very difficult to beat
the existing options with expressive power or elegance.

You seem to have been surprised with some advanced concepts and idioms
in this discussion. Really, apart from its indentation syntax, Python
offers no unique or even rare software engineering concepts (Python's
emphasis duck-typing comes close to being distinctive). You'll find
equivalents in quite many languages, and in active, money-making uses.

> I'm not holding a gun to your head and forcing you to read my posts.

Follow your own advice.


Marko


From snailcoder at retrosite.invalid  Wed Nov 25 17:30:04 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Wed, 25 Nov 2015 23:30:04 +0100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <mailman.96.1448484959.20593.python-list@python.org>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
Message-ID: <n35ckk$9q0$1@dont-email.me>

Hi

It seems that links on that Wikipedia page follow the structure :
<a href="..." title="...">

You could extract a list of link titles with something like :
re.findall( r'\<a[^>]+title="(.+?)"', html )

HTH,

-Grobu-


On 25/11/15 21:55, MRAB wrote:
> On 2015-11-25 20:42, ryguy7272 wrote:
>> Hello experts.  I'm looking at this url:
>> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
>>
>> I'm trying to figure out how to list all 'a title' elements.  For
>> instance, I see the following:
>> <a title="Accident, Maryland"
>> href="/wiki/Accident,_Maryland">Accident</a>
>> <a class="new" title="Ala-Lemu (page does not exist)"
>> href="/w/index.php?title=Ala-Lemu&action=edit&redlink=1">Ala-Lemu</a>
>> <a title="Alert, Nunavut" href="/wiki/Alert,_Nunavut">Alert</a>
>> <a title="Apocalypse Peaks" href="/wiki/Apocalypse_Peaks">Apocalypse
>> Peaks</a>
>>
>> So, I tried putting a script together to get 'title'.  Here's my attempt.
>>
>> import requests
>> import sys
>> from bs4 import BeautifulSoup
>>
>> url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
>> source_code = requests.get(url)
>> plain_text = source_code.text
>> soup = BeautifulSoup(plain_text)
>> for link in soup.findAll('title'):
>>      print(link)
>>
>> All that does is get the title of the page.  I tried to get the links
>> from that url, with this script.
>>
> A 'title' element has the form "<title ...>". What you should be looking
> for are 'a' elements, those of the form "<a ...>".
>
>> import urllib2
>> import re
>>
>> #connect to a URL
>> website =
>> urllib2.urlopen('https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names')
>>
>>
>> #read html code
>> html = website.read()
>>
>> #use re.findall to get all the links
>> links = re.findall('"((http|ftp)s?://.*?)"', html)
>>
>> print links
>>
>> That doesn't work wither.  Basically, I'd like to see this.
>>
>> Accident
>> Ala-Lemu
>> Alert
>> Apocalypse Peaks
>> Athol
>> ?
>> Barbecue
>> B?stad
>> Bastardstown
>> Batman
>> Bathmen (Battem), Netherlands
>> ...
>> Worms
>> Yell
>> Zigzag
>> Zzyzx
>>
>> How can I do that?
>> Thanks all!!



From ian.g.kelly at gmail.com  Wed Nov 25 17:38:27 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 15:38:27 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <5656229A.2000309@rece.vub.ac.be>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <5655FDAC.4070305@rece.vub.ac.be>
 <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>
 <5656229A.2000309@rece.vub.ac.be>
Message-ID: <CALwzidngZMafqiWv-2dZPEsAP+5qVDST2fW0X8i5Y4m0YdJ3Uw@mail.gmail.com>

On Wed, Nov 25, 2015 at 2:05 PM, Antoon Pardon
<antoon.pardon at rece.vub.ac.be> wrote:
> Op 25-11-15 om 21:39 schreef Ian Kelly:
>> On Wed, Nov 25, 2015 at 11:27 AM, Antoon Pardon
>> <antoon.pardon at rece.vub.ac.be> wrote:
>>> I don't know what you are talking about. The first thing I have argued
>>> is that () is a literal. Then I have expaned that to that something
>>> like (3, 5, 8) is a literal. I never argued that tuple expressions
>>> in general are literals. And one way I supported my point was with the
>>> following quote from the python language reference.
>>>
>>>   Literals are notations for constant values of some built-in types.
>>>
>>> And I think that the things I argued were literals, were in fact
>>> constant values of some built-in type.
>>
>> I believe that sentence from the docs is using "some" to mean "not
>> all", whereas you are apparently using it to mean "any".
>>
>> frozenset([1,2,3]) constructs a constant value of a built-in type.
>> Would you consider that a literal?
>
> I am inclined to say yes, because a sufficient intelligent compilor
> can compute the value and store it do be retrieved and bound to a
> target when needed.

I'm curious then what you think of this:

from collections import namedtuple

class Point(namedtuple("Point", "x y")): pass

Point(17, 12)

Still a constant, but not a built-in type. Would you consider that a literal?


From zachary.ware+pylist at gmail.com  Wed Nov 25 17:39:28 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Wed, 25 Nov 2015 16:39:28 -0600
Subject: Help needed with compiling python
In-Reply-To: <8737vt927c.fsf@Equus.decebal.nl>
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
Message-ID: <CAKJDb-PZjpiZkgSGAgOW0wSENnGOqtwTNSq9HQdMJLcirdU7Og@mail.gmail.com>

On Wed, Nov 25, 2015 at 3:52 PM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> My system python was all-ready damaged: that is why I wanted to build
> myself.

Then you should try to repair the system Python install via the system
package manager.  It's not worth the hassle to try to replace it; it
almost certainly won't work for some strange corner case that won't
bite you until 3 months from now.  It's perfectly OK to have a second
Python install in /usr/local, even of the same version as the system
Python.

> It is an openSUSE system. I installed the readline with:
>     zypper install readline-devel
>
> The strange thing is that it does mot compile anymore now. I get:
> Python build finished, but the necessary bits to build these modules were not found:
>     _bsddb             _tkinter           bsddb185
>     dbm                dl                 gdbm
>     imageop            sunaudiodev
>     To find the necessary bits, look in setup.py in detect_modules() for the module's name.

Before you installed readline-devel, readline would have been listed
there as well.  It's ok to have modules listed there if you don't need
those particular modules.  Most of those are actually deprecated, and
have been removed from Python 3.  Of those that remain, _tkinter
requires tcl-devel and tk-devel; dbm and gdbm require similarly named
development packages (I have no experience with using dbm/gdbm).

-- 
Zach


From bc at freeuk.com  Wed Nov 25 17:41:56 2015
From: bc at freeuk.com (BartC)
Date: Wed, 25 Nov 2015 22:41:56 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87k2p54tdr.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
Message-ID: <n35dbc$ckb$1@dont-email.me>

On 25/11/2015 22:16, Marko Rauhamaa wrote:
> BartC <bc at freeuk.com>:
>
>> I'm interested in language design because that's what I've done on and
>> off for over 30 years. And I'm discussing some design decisions in
>> Python.
>
> That *is* a fun ambition, useful or not.

(At the moment, it's mostly fun. But in the past I actually needed the 
languages to do my job (designing microprocessor hardware). The 
scripting languages came a bit later, to go with my 3D graphics 
applications.)

> You seem to have been surprised with some advanced concepts and idioms
> in this discussion. Really, apart from its indentation syntax, Python
> offers no unique or even rare software engineering concepts (Python's
> emphasis duck-typing comes close to being distinctive). You'll find
> equivalents in quite many languages, and in active, money-making uses.

Maybe you're too familiar with it. But the idea of /executing/ the 
function and other definitions in a file, instead of they just being 
there, is novel.

-- 
Bartc



From ryanshuell at gmail.com  Wed Nov 25 17:48:40 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 25 Nov 2015 14:48:40 -0800 (PST)
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <n35ckk$9q0$1@dont-email.me>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
Message-ID: <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>

On Wednesday, November 25, 2015 at 5:30:14 PM UTC-5, Grobu wrote:
> Hi
> 
> It seems that links on that Wikipedia page follow the structure :
> <a href="..." title="...">
> 
> You could extract a list of link titles with something like :
> re.findall( r'\<a[^>]+title="(.+?)"', html )
> 
> HTH,
> 
> -Grobu-
> 
> 
> On 25/11/15 21:55, MRAB wrote:
> > On 2015-11-25 20:42, ryguy7272 wrote:
> >> Hello experts.  I'm looking at this url:
> >> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
> >>
> >> I'm trying to figure out how to list all 'a title' elements.  For
> >> instance, I see the following:
> >> <a title="Accident, Maryland"
> >> href="/wiki/Accident,_Maryland">Accident</a>
> >> <a class="new" title="Ala-Lemu (page does not exist)"
> >> href="/w/index.php?title=Ala-Lemu&action=edit&redlink=1">Ala-Lemu</a>
> >> <a title="Alert, Nunavut" href="/wiki/Alert,_Nunavut">Alert</a>
> >> <a title="Apocalypse Peaks" href="/wiki/Apocalypse_Peaks">Apocalypse
> >> Peaks</a>
> >>
> >> So, I tried putting a script together to get 'title'.  Here's my attempt.
> >>
> >> import requests
> >> import sys
> >> from bs4 import BeautifulSoup
> >>
> >> url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
> >> source_code = requests.get(url)
> >> plain_text = source_code.text
> >> soup = BeautifulSoup(plain_text)
> >> for link in soup.findAll('title'):
> >>      print(link)
> >>
> >> All that does is get the title of the page.  I tried to get the links
> >> from that url, with this script.
> >>
> > A 'title' element has the form "<title ...>". What you should be looking
> > for are 'a' elements, those of the form "<a ...>".
> >
> >> import urllib2
> >> import re
> >>
> >> #connect to a URL
> >> website =
> >> urllib2.urlopen('https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names')
> >>
> >>
> >> #read html code
> >> html = website.read()
> >>
> >> #use re.findall to get all the links
> >> links = re.findall('"((http|ftp)s?://.*?)"', html)
> >>
> >> print links
> >>
> >> That doesn't work wither.  Basically, I'd like to see this.
> >>
> >> Accident
> >> Ala-Lemu
> >> Alert
> >> Apocalypse Peaks
> >> Athol
> >> ?
> >> Barbecue
> >> B?stad
> >> Bastardstown
> >> Batman
> >> Bathmen (Battem), Netherlands
> >> ...
> >> Worms
> >> Yell
> >> Zigzag
> >> Zzyzx
> >>
> >> How can I do that?
> >> Thanks all!!



Thanks!!  Is that regex?  Can you explain exactly what it is doing?
Also, it seems to pick up a lot more than just the list I wanted, but that's ok, I can see why it does that.  

Can you just please explain what it's doing???


From lac at openend.se  Wed Nov 25 17:58:38 2015
From: lac at openend.se (Laura Creighton)
Date: Wed, 25 Nov 2015 23:58:38 +0100
Subject: Help needed with compiling python
In-Reply-To: <8737vt927c.fsf@Equus.decebal.nl>
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
Message-ID: <201511252258.tAPMwcdp026898@fido.openend.se>

In a message of Wed, 25 Nov 2015 22:52:23 +0100, Cecil Westerhof writes:
>
>My system python was all-ready damaged: that is why I wanted to build
>myself.

Your Suse system probably wants to use python for something.  If your
system python is damaged, you badly need to fix that, using the 
system package managers tools, before Suse does some sort of update
on you, using the broken python, which damages more of your system.

Laura


From rosuav at gmail.com  Wed Nov 25 18:06:21 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 10:06:21 +1100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
Message-ID: <CAPTjJmogm7sc8m=czauTNnQD12=xoynO09GX74jwJ9JGcgZkzw@mail.gmail.com>

On Thu, Nov 26, 2015 at 9:48 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
> Thanks!!  Is that regex?  Can you explain exactly what it is doing?
> Also, it seems to pick up a lot more than just the list I wanted, but that's ok, I can see why it does that.
>
> Can you just please explain what it's doing???

It's a trap!

Don't use a regex to parse HTML, unless you're deliberately trying to
entice young and innocent programmers to the dark side.

ChrisA


From snailcoder at retrosite.invalid  Wed Nov 25 18:33:48 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Thu, 26 Nov 2015 00:33:48 +0100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
Message-ID: <n35gc3$r1k$1@dont-email.me>


On 25/11/15 23:48, ryguy7272 wrote:
>> re.findall( r'\<a[^>]+title="(.+?)"', html )
[ ... ]
> Thanks!!  Is that regex?  Can you explain exactly what it is doing?
> Also, it seems to pick up a lot more than just the list I wanted, but that's ok, I can see why it does that.
>
> Can you just please explain what it's doing???
>

Yes it's a regular expression. Because RegEx's use the backslash as an 
escape character, it is advisable to use the "raw string" prefix (r 
before single/double/triple quote. To illustrate it with an example :
	>>> print "1\n2"
	1
	2
	>>> print r"1\n2"
	1\n2
As the backslash escape character is "neutralized" by the raw string, 
you can use the usual RegEx syntax at leisure :

\<a[^>]+title="(.+?)"

\<	was a mistake on my part, a single < is perfectly enough
[^>]	is a class definition, and the caret (^) character indicates 
negation. Thus it means : any character other than >
+	incidates repetition : one or more of the previous element
.	will match just anything
.+"	is a _greedy_ pattern that would match anything until it encountered 
a double quote

The problem with a greedy pattern is that it doesn't stop at the first 
match. To illustrate :
 >>> a = re.search( r'".+"', 'title="this is a test" class="test"' )
 >>> a.group()
'"this is a test" class="test"'

It matches the first quote up to the last one.
On the other hand, you can use the "?" modifier to specify a non-greedy 
pattern :

 >>> b = re.search( r'".+?"', 'title="this is a test" class="test"' )
'"this is a test"'

It matches the first quote and stops looking for further matches after 
the second quote.

Finally, the parentheses are used to indicate a capture group :
 >>> a = re.search( r'"this (is) a (.+?)"', 'title="this is a test" 
class="test"' )
 >>> a.groups()
('is', 'test')


You can find detailed explanations about Python regular expressions at 
this page : https://docs.python.org/2/howto/regex.html

HTH,

-Grobu-



From ryanshuell at gmail.com  Wed Nov 25 18:37:15 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Wed, 25 Nov 2015 15:37:15 -0800 (PST)
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <n35gc3$r1k$1@dont-email.me>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <n35gc3$r1k$1@dont-email.me>
Message-ID: <e55c49e2-539d-4f62-89f7-34fa3882ff59@googlegroups.com>

On Wednesday, November 25, 2015 at 6:34:00 PM UTC-5, Grobu wrote:
> On 25/11/15 23:48, ryguy7272 wrote:
> >> re.findall( r'\<a[^>]+title="(.+?)"', html )
> [ ... ]
> > Thanks!!  Is that regex?  Can you explain exactly what it is doing?
> > Also, it seems to pick up a lot more than just the list I wanted, but that's ok, I can see why it does that.
> >
> > Can you just please explain what it's doing???
> >
> 
> Yes it's a regular expression. Because RegEx's use the backslash as an 
> escape character, it is advisable to use the "raw string" prefix (r 
> before single/double/triple quote. To illustrate it with an example :
> 	>>> print "1\n2"
> 	1
> 	2
> 	>>> print r"1\n2"
> 	1\n2
> As the backslash escape character is "neutralized" by the raw string, 
> you can use the usual RegEx syntax at leisure :
> 
> \<a[^>]+title="(.+?)"
> 
> \<	was a mistake on my part, a single < is perfectly enough
> [^>]	is a class definition, and the caret (^) character indicates 
> negation. Thus it means : any character other than >
> +	incidates repetition : one or more of the previous element
> .	will match just anything
> .+"	is a _greedy_ pattern that would match anything until it encountered 
> a double quote
> 
> The problem with a greedy pattern is that it doesn't stop at the first 
> match. To illustrate :
>  >>> a = re.search( r'".+"', 'title="this is a test" class="test"' )
>  >>> a.group()
> '"this is a test" class="test"'
> 
> It matches the first quote up to the last one.
> On the other hand, you can use the "?" modifier to specify a non-greedy 
> pattern :
> 
>  >>> b = re.search( r'".+?"', 'title="this is a test" class="test"' )
> '"this is a test"'
> 
> It matches the first quote and stops looking for further matches after 
> the second quote.
> 
> Finally, the parentheses are used to indicate a capture group :
>  >>> a = re.search( r'"this (is) a (.+?)"', 'title="this is a test" 
> class="test"' )
>  >>> a.groups()
> ('is', 'test')
> 
> 
> You can find detailed explanations about Python regular expressions at 
> this page : https://docs.python.org/2/howto/regex.html
> 
> HTH,
> 
> -Grobu-



Wow!  Awesome!  I bookmarked that link!  
Thanks for everything!!!


From rosuav at gmail.com  Wed Nov 25 18:42:34 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 10:42:34 +1100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <e55c49e2-539d-4f62-89f7-34fa3882ff59@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <n35gc3$r1k$1@dont-email.me>
 <e55c49e2-539d-4f62-89f7-34fa3882ff59@googlegroups.com>
Message-ID: <CAPTjJmqH1cBdZ+Z1maPkSJ+-FUvAH_uQ+S7_vXPtATO2m1ZT-w@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:37 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
> Wow!  Awesome!  I bookmarked that link!
> Thanks for everything!!!

Also bookmark this link:

http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags

And read it before you do any parsing of HTML using regular expressions.

ChrisA


From snailcoder at retrosite.invalid  Wed Nov 25 18:44:55 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Thu, 26 Nov 2015 00:44:55 +0100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <mailman.103.1448492791.20593.python-list@python.org>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <mailman.103.1448492791.20593.python-list@python.org>
Message-ID: <n35h0v$stn$1@dont-email.me>

On 26/11/15 00:06, Chris Angelico wrote:
> On Thu, Nov 26, 2015 at 9:48 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
>> Thanks!!  Is that regex?  Can you explain exactly what it is doing?
>> Also, it seems to pick up a lot more than just the list I wanted, but that's ok, I can see why it does that.
>>
>> Can you just please explain what it's doing???
>
> It's a trap!
>
> Don't use a regex to parse HTML, unless you're deliberately trying to
> entice young and innocent programmers to the dark side.
>
> ChrisA
>

Sorry, I wasn't aware of regex being on the dark side :-)
Now that you mention it, I suppose that their being complex and 
error-inducing could lead to broken code all too easily when there is a 
reliable, ready-made solution like BeautifulSoup.



From marko at pacujo.net  Wed Nov 25 18:53:26 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 01:53:26 +0200
Subject: Screen scraper to get all 'a title' elements
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <mailman.103.1448492791.20593.python-list@python.org>
 <n35h0v$stn$1@dont-email.me>
Message-ID: <87y4dl3abt.fsf@elektro.pacujo.net>

Grobu <snailcoder at retrosite.invalid>:

> Sorry, I wasn't aware of regex being on the dark side :-)

No, regular expressions are great for many purposes. Parsing
context-free syntax isn't one of them.

See:

  <URL: https://en.wikipedia.org/wiki/Chomsky_hierarchy#The_hierarchy>

Most modern programming languages including HTML are context-free. Their
structure is too rich for regular expressions to capture.

Regular expressions can handle any regular language just fine. They are
commonly used to define the lexical tokens of a language.


Marko


From rosuav at gmail.com  Wed Nov 25 18:54:04 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 10:54:04 +1100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <n35h0v$stn$1@dont-email.me>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <mailman.103.1448492791.20593.python-list@python.org>
 <n35h0v$stn$1@dont-email.me>
Message-ID: <CAPTjJmqzWXjAJo_=3xtBYhUfnb2TwtrmC9AYYmiiC9G3v58zsw@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:44 AM, Grobu <snailcoder at retrosite.invalid> wrote:
> On 26/11/15 00:06, Chris Angelico wrote:
>>
>> On Thu, Nov 26, 2015 at 9:48 AM, ryguy7272 <ryanshuell at gmail.com> wrote:
>>>
>>> Thanks!!  Is that regex?  Can you explain exactly what it is doing?
>>> Also, it seems to pick up a lot more than just the list I wanted, but
>>> that's ok, I can see why it does that.
>>>
>>> Can you just please explain what it's doing???
>>
>>
>> It's a trap!
>>
>> Don't use a regex to parse HTML, unless you're deliberately trying to
>> entice young and innocent programmers to the dark side.
>>
>> ChrisA
>>
>
> Sorry, I wasn't aware of regex being on the dark side :-)
> Now that you mention it, I suppose that their being complex and
> error-inducing could lead to broken code all too easily when there is a
> reliable, ready-made solution like BeautifulSoup.

Regular expressions have their uses, but parsing HTML is not one of
them. The most important use of a regex is letting an end user control
the search pattern; it's a compact language for describing a variety
of text search concepts. For hard-coded regular expressions, there are
some places where they're very good, and a lot of places where they're
the wrong tool for the job. And one of those wrong-tool-for-job places
is parsing stuff that fundamentally cannot be parsed with regexes,
such as HTML. You _need_ a proper parser, which is what Beautiful Soup
is for.

ChrisA


From rosuav at gmail.com  Wed Nov 25 18:59:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 10:59:14 +1100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <87y4dl3abt.fsf@elektro.pacujo.net>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <mailman.103.1448492791.20593.python-list@python.org>
 <n35h0v$stn$1@dont-email.me> <87y4dl3abt.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmqjyA-zwaECDn3BjCJCpzSQtaMWHOtauSvo2Uz5CJM0VQ@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:53 AM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Regular expressions can handle any regular language just fine. They are
> commonly used to define the lexical tokens of a language.

Not sure about _defining_ them, but they're certainly often used to
_recognize_ them, eg in syntax highlighters.

ChrisA


From steve at pearwood.info  Wed Nov 25 19:10:58 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 11:10:58 +1100
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <mailman.84.1448476089.20593.python-list@python.org>
Message-ID: <56564e14$0$1595$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 05:27 am, Antoon Pardon wrote:

> Op 25-11-15 om 18:40 schreef Steven D'Aprano:
>> On Wed, 25 Nov 2015 08:56 pm, Antoon Pardon wrote:
>> 
>>> Since (x, y, z) is not a fixed value, it is not a literal.
>> 
>> Right. And therefore, (x, y, z) syntax is not syntax for a literal. Hence
>> why the Python docs call it a tuple display instead of a tuple literal --
>> no matter what x, y, z are. Even if they themselves are literals, that's
>> just a special case that *some* compiler versions may be able to handle.
>> 
>> You call this "picking nits", but if so, they are nits that are twice the
>> size of an an elephant and painted bright yellow. Your language arguing
>> about "tuple literals" seems to be based on the idea that it is usually a
>> constant and that cases like (x+1, y+2) is some unusual, rare corner
>> case -- what you call "nits".
> 
> I don't know what you are talking about. The first thing I have argued
> is that () is a literal. 

How embarrassing that Python doesn't treat it as a literal, but as an
expression.


> And one way I supported my point was with the
> following quote from the python language reference.
> 
>   Literals are notations for constant values of some built-in types.
> 
> And I think that the things I argued were literals, were in fact
> constant values of some built-in type.

Since you didn't bother to provide a link, I googled for that quote, and
here's a page that gives the canonical set of literals available in Python:

https://docs.python.org/2/reference/lexical_analysis.html#literals

https://docs.python.org/3/reference/lexical_analysis.html#literals

I see strings, ints, floats, but no tuples, lists or dicts.

It takes either great chutzpah or great stupidity to use the official
documentation to argue in favour of a point which is contradicted by that
very same documentation.

The Python docs *define* "literal" to only refer to certain types. That
definition is related to the grammar of Python:

https://docs.python.org/3/reference/grammar.html

It would be silly, wasteful and error-prone to define two sorts of tuple
displays:

"tuple displays where each component is a literal"

"tuple displays where at least one component is not a literal"


as you want to distinguish. Now obviously this is a legitimate distinction
to make in some circumstances: the compiler may (or may not) be able
optimise the first case in some way. But it's not a distinction that makes
sense for the parser. It makes no difference to the parser whether you have
(1, 2) or (1, x), it gets parsed the same way. To the parser, there is only
one sort of tuple display, and it is absolutely not a literal.

The terminology used for lexical analysis is the terminology used for the
parser, not the peephole optimizer. All Python compilers must have a
parser, and they must agree on the grammar. But optimization is
implementation dependent. There is talk about adding a switch to Python to
disable all peep-hole optimizations, which means whether (1, 2) gets
compiled to a BUILD_CONST or a BUILD_TUPLE will depend on a runtime switch.

The bottom-line is that tuples, lists, sets and dicts are compound data
types, and while it is easy and convenient to talk about "tuple literals"
that's sloppy language which is not supported by the language reference.
When this fact is pointed out, there are multiple sensible strategies
available:

(1) we can acknowledge that "tuple literal" is sloppy language, and vow
never to use it again;

(2) we can acknowledge that "tuple literal" is sloppy language, but argue
that it's convenient to use, more familiar than "tuple display", and most
people will understand what you mean, and so we'll continue to use it no
matter how sloppy it is;

(3) or we can declare that the definition in the language reference is
wrong, that we know better.


What I've never seen before though is what you appear to have done:

(4) Respond that the language reference, which clearly and obviously does
NOT include tuples in the list of types that can be described
as "literals", supports your claim that tuples are literals.



-- 
Steven



From steve at pearwood.info  Wed Nov 25 19:31:27 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 11:31:27 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
Message-ID: <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 09:41 am, BartC wrote:

> Maybe you're too familiar with it. But the idea of executing the
> function and other definitions in a file, instead of they just being
> there, is novel.


It really, truly isn't. Your viewpoint is clouded by too much immersion in
crippled languages. *Old and obsolete versions* of crippled languages.
Dynamic creation of functions goes back to the 1950s.

Functions in Python are *first class values*, just like ints, strings, lists
etc. That means functions can be passed around as arguments, assigned to
variables, returned from functions, and created on the fly as needed. This
is not an innovation from Python -- Python rarely, if ever, innovates. By
the time any feature hits Python (yes, even significant indentation) it has
typically been proven in at least one other language.

Languages with first class functions include Perl, Javascript, Lua, PHP,
Tcl/Tk, Io, Go, Rust, Maple, Mathematica, Smalltalk, Swift, and varied mix
of old (Smalltalk and Perl) and new (Rust and Swift).

It is almost unthinkable to imagine a functional programming language
without this feature, and sure enough Scala, Haskell, ML, Clojure, and
Scheme have it -- as does Lisp, which is the second oldest high level
language in existence. Only Fortran is older.

Delphi (a variant on Pascal/Algol) has supported them since 2009. C++, C#
and Objective C have support for first class functions. Even Java 8 and
above includes this feature.

In 2015, it's hard to think of any non-obsolete, non-toy language which
doesn't treat functions as first-class values, including creating them on
the fly. Fortran and C perhaps.



-- 
Steven



From random832 at fastmail.com  Wed Nov 25 19:52:55 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 26 Nov 2015 00:52:55 +0000 (UTC)
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <CAPTjJmoyGi04Dnxxp1AFytLkWQg=D4ccXqE6OwfJJMgp7fg1YA@mail.gmail.com>
 <858u5lc0r7.fsf@benfinney.id.au>
Message-ID: <n35l57$ots$1@ger.gmane.org>

On 2015-11-25, Ben Finney <ben+python at benfinney.id.au> wrote:
> That is, the ?2? in ?cartesian_point = (2, 3)? means something different
> than in ?cartesian_point = (3, 2)?.
>
> Whereas the ?2? in ?test_scores = [2, 3]? means exactly the same as in
> ?test_scores = [3, 2]?.
>
> If each position in the sequence gives the value there a different
> menaning, use a tuple; if not, use a list.

I don't think that's really right. The absence of first-class
multisets in python does mean that lists get "abused" for that
purpose, but I don't think that means that there's no legitimate
use-case for a list (i.e. a mutable sequence in which position is
significant).

The difference between a tuple and a list is that one is mutable
and the other is not. The difference you are describing is
between a list and a multiset (or a tuple and an immutable
multiset).



From steve at pearwood.info  Wed Nov 25 19:53:51 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 11:53:51 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
Message-ID: <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 01:34 am, BartC wrote:

> On 25/11/2015 13:53, Marko Rauhamaa wrote:
>> BartC <bc at freeuk.com>:
>>
>>> Using tuples in the same way that other languages implement records is
>>> going to be difficult if you can't change the values of the fields!
>>
>> Guido could decide tomorrow that tuples are mutable.
> 
> (Could that be done without breaking existing code? And what then would
> be the difference between them and lists?)


No it could not, and no Guido could not decide to make them mutable. 

Well, strictly speaking he could make that decision, but the other core
developers would not go along with such a stupid backwards-incompatible
change. I don't know what would happen if Guido did make that decision -- I
suppose it would provoke some sort of constitutional crisis (figuratively
speaking), like what would happen if the Queen of the UK refused to sign
into law legislation after being lawfully asked to do so by the Prime
Minister. (The Queen has the power to reject any legislation put to her by
the Prime Minister, so long as she does not actually make use of that
power.)

Guido, as BDFL, has every right to make tuples mutable, or remove numbers
from the language, so long as he does not actually do so.

Making tuples mutable would break their use as dictionary keys, which is a
*critical* use.

https://docs.python.org/2/faq/design.html#why-must-dictionary-keys-be-immutable



>> Anyway, Python has two ways to represent records: classes and tuples.
>> Tuples are nice because they are concise and ad hoc. Often you start
>> with a scalar value, then turn it into a tuple. After a while your handy
>> tuple turns out a bit cumbersome to use so you convert it into an actual
>> class.
> 
> This is how records are handled in another language which I believe is
> simpler than Python: http://pastebin.com/vhsJML8U
> 
> This also implements my example from earlier in the thread. Now compare
> with Python's approach.
> 
> OK, that also needs two concepts, a list, and a record. But the
> distinction is now completely obvious. Records are also mutable. It
> would also be clear why you can't append to a record.
> 
> Now try explaining again to me how you would use tuples for the same
> thing...

In Pascal, strings are mutable. (Well, technically, standard Pascal doesn't
define a string data type, but most implementations do.) So you typically
have some function like:

insert(thestring, substring, pos)

which modifies thestring in place. In Python, strings are immutable, so the
equivalent of insert() would be a function that returns a new string:

thestring = insert(thestring, substring, pos)

It's not exactly an earth-shattering difference.

The implementation is simple that it is almost pointless to put it in a
function:

def insert(s, substring, pos):
    return s[:pos] + substring + s[pos:]


Tuples-as-records are no different. Instead of modifying the existing
record, you create a new one. If that's inconvenient, then use a class,
which will be mutable by default.



-- 
Steven



From snailcoder at retrosite.invalid  Wed Nov 25 20:05:34 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Thu, 26 Nov 2015 02:05:34 +0100
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <n35h0v$stn$1@dont-email.me>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
 <mailman.96.1448484959.20593.python-list@python.org>
 <n35ckk$9q0$1@dont-email.me>
 <c1e43997-0da3-4b93-b9af-98a2568eff9d@googlegroups.com>
 <mailman.103.1448492791.20593.python-list@python.org>
 <n35h0v$stn$1@dont-email.me>
Message-ID: <n35lo5$b06$1@dont-email.me>

Chris, Marko, thank you both for your links and explanations!


From wingusr at gmail.com  Wed Nov 25 20:15:49 2015
From: wingusr at gmail.com (TP)
Date: Wed, 25 Nov 2015 17:15:49 -0800
Subject: Screen scraper to get all 'a title' elements
In-Reply-To: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
Message-ID: <CAMEax76MwY323=z9n_o+=zJQhAQdRpeFM-nKEbARG__UEoGxmg@mail.gmail.com>

On Wed, Nov 25, 2015 at 12:42 PM, ryguy7272 <ryanshuell at gmail.com> wrote:
> Hello experts.  I'm looking at this url:
> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names

Wildly offtopic but interesting, easy way to grab/analyze Wikipedia
data using F# instead of Python
http://evelinag.com/blog/2015/11-18-f-tackles-james-bond/

In your particular case something like:

open FSharp.Data
let [<Literal>] wikiURL =
"https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
type PlaceNamesProvider = HtmlProvider<wikiURL>

let placeNamesWiki = PlaceNamesProvider()
for row in placeNamesWiki.Tables.``Short & medium length names``.Rows do
  printfn "%s" row.Column1


From bc at freeuk.com  Wed Nov 25 20:23:16 2015
From: bc at freeuk.com (BartC)
Date: Thu, 26 Nov 2015 01:23:16 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n35mps$dv8$1@dont-email.me>

On 26/11/2015 00:31, Steven D'Aprano wrote:
> On Thu, 26 Nov 2015 09:41 am, BartC wrote:
>
>> Maybe you're too familiar with it. But the idea of executing the
>> function and other definitions in a file, instead of they just being
>> there, is novel.
>
>
> It really, truly isn't. Your viewpoint is clouded by too much immersion in
> crippled languages. *Old and obsolete versions* of crippled languages.
> Dynamic creation of functions goes back to the 1950s.
>
> Functions in Python are *first class values*, just like ints, strings, lists
> etc. That means functions can be passed around as arguments, assigned to
> variables, returned from functions, and created on the fly as needed. This
> is not an innovation from Python -- Python rarely, if ever, innovates. By
> the time any feature hits Python (yes, even significant indentation) it has
> typically been proven in at least one other language.
>
> Languages with first class functions include Perl, Javascript, Lua, PHP,
> Tcl/Tk, Io, Go, Rust, Maple, Mathematica, Smalltalk, Swift, and varied mix
> of old (Smalltalk and Perl) and new (Rust and Swift).
>
> It is almost unthinkable to imagine a functional programming language
> without this feature, and sure enough Scala, Haskell, ML, Clojure, and
> Scheme have it -- as does Lisp, which is the second oldest high level
> language in existence. Only Fortran is older.
>
> Delphi (a variant on Pascal/Algol) has supported them since 2009. C++, C#
> and Objective C have support for first class functions. Even Java 8 and
> above includes this feature.
>
> In 2015, it's hard to think of any non-obsolete, non-toy language which
> doesn't treat functions as first-class values, including creating them on
> the fly. Fortran and C perhaps.

It's funny then that the vast majority of top-level function definitions 
I see in Python (and import and class statements too) are decidedly static.

The names are declared, but the names are rarely bound to anything else. 
Functions are just called the same boring way they are in C.

/They might as well be static definitions/.

(In fact, all this dynamic set-up, while it makes for an elegant and 
consistent language, probably also makes it unnecessarily harder to 
accelerate.)

Clearly a huge amount of programming can be done without having to deal 
with first-class functions (or constructing functions at run-time; that 
sounds fun). (Or without using OOP, another thing I can't stand.)

Some people just don't want to be functional programmers. It is elitist 
to try and make out it that it is that important.

If lots of languages now have functional features, it's more likely to 
be a case of keeping up with the Joneses.

-- 
Bartc


From ned at nedbatchelder.com  Wed Nov 25 20:52:21 2015
From: ned at nedbatchelder.com (Ned Batchelder)
Date: Wed, 25 Nov 2015 17:52:21 -0800 (PST)
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n35mps$dv8$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me>
 <87k2p54tdr.fsf@elektro.pacujo.net> <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
Message-ID: <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>

On Wednesday, November 25, 2015 at 8:23:36 PM UTC-5, BartC wrote:
> On 26/11/2015 00:31, Steven D'Aprano wrote:
> > On Thu, 26 Nov 2015 09:41 am, BartC wrote:
> >
> >> Maybe you're too familiar with it. But the idea of executing the
> >> function and other definitions in a file, instead of they just being
> >> there, is novel.
> >
> >
> > It really, truly isn't. Your viewpoint is clouded by too much immersion in
> > crippled languages. *Old and obsolete versions* of crippled languages.
> > Dynamic creation of functions goes back to the 1950s.
> >
> > Functions in Python are *first class values*, just like ints, strings, lists
> > etc. That means functions can be passed around as arguments, assigned to
> > variables, returned from functions, and created on the fly as needed. This
> > is not an innovation from Python -- Python rarely, if ever, innovates. By
> > the time any feature hits Python (yes, even significant indentation) it has
> > typically been proven in at least one other language.
> >
> > Languages with first class functions include Perl, Javascript, Lua, PHP,
> > Tcl/Tk, Io, Go, Rust, Maple, Mathematica, Smalltalk, Swift, and varied mix
> > of old (Smalltalk and Perl) and new (Rust and Swift).
> >
> > It is almost unthinkable to imagine a functional programming language
> > without this feature, and sure enough Scala, Haskell, ML, Clojure, and
> > Scheme have it -- as does Lisp, which is the second oldest high level
> > language in existence. Only Fortran is older.
> >
> > Delphi (a variant on Pascal/Algol) has supported them since 2009. C++, C#
> > and Objective C have support for first class functions. Even Java 8 and
> > above includes this feature.
> >
> > In 2015, it's hard to think of any non-obsolete, non-toy language which
> > doesn't treat functions as first-class values, including creating them on
> > the fly. Fortran and C perhaps.
> 
> It's funny then that the vast majority of top-level function definitions 
> I see in Python (and import and class statements too) are decidedly static.
> 
> The names are declared, but the names are rarely bound to anything else. 
> Functions are just called the same boring way they are in C.
> 
> /They might as well be static definitions/.
> 
> (In fact, all this dynamic set-up, while it makes for an elegant and 
> consistent language, probably also makes it unnecessarily harder to 
> accelerate.)
> 
> Clearly a huge amount of programming can be done without having to deal 
> with first-class functions (or constructing functions at run-time; that 
> sounds fun). (Or without using OOP, another thing I can't stand.)
> 
> Some people just don't want to be functional programmers. It is elitist 
> to try and make out it that it is that important.
> 
> If lots of languages now have functional features, it's more likely to 
> be a case of keeping up with the Joneses.

I almost started to explain about how yes, Python is often written in
conservative static ways. I was going to mention that a little dynamic
nature goes a long way, and is never far from the surface in even the
simplest Python programs.

But I won't, because I'm not sure you're really interested.  There's a
pattern here of people trying to explain Python to you, and eventually,
after many words, getting to some kind of shared understanding, only
for you to shrug it all off as a fad, or pocket-lining, or needless
complexity.

For someone who claims to be interested in language design, you're
remarkably dismissive of pretty much the entire industry.  I don't think
it's worth the effort to try to change your mind.

--Ned.



From steve at pearwood.info  Wed Nov 25 21:01:56 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 13:01:56 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
Message-ID: <56566815$0$1598$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 12:20 am, BartC wrote:

> On 25/11/2015 10:52, Steven D'Aprano wrote:
>> On Wed, 25 Nov 2015 07:14 pm, Antoon Pardon wrote:
> 
>>> What exactly is your point?
>>
>> That there is a simple analogy between the distinction between code
>> inside/outside a for-loop, and code inside/outside a function. If you can
>> understand why this loops forever, instead of just twice, then you can
>> understand why function defaults work the way they do:
>>
>> L = [1, 2]
>> for i in L:
>>      L.append(i)
>>      print(L)
>>
>>
>> There is nothing "bizarre" or complicated or difficult to understand
>> happening here.
> 
> What do you think most people would expect to happen here? 

I wouldn't try to guess what "most" people would expect. Their expectations
would depend on what exposure they have had with programming languages, if
any, what languages those are, and how well they grok the idea of
simulating code in their own head.



> I know, 
> because you gave a spoiler, that it loops forever, otherwise I wouldn't
> be sure /without trying it/ (but I tried it anyway).
> 
> Here's the same code in a somewhat different language:
> 
> L := (1,2)
> for i in L do
> |   L append:= i
> |   println L
> od
> 
> And this is the output:
> 
> (1,2,1)
> (1,2,1,2)
> 
> Which output (infinite series of [1,2,1,2,1,....] or the above) is more
> sensible, and which do you think people might prefer?

The infinite loop is more sensible, and people would prefer the above
output. Who wants an infinite loop? That's nearly always a bug.

But consider why, bug or no bug, the Python version which leads to an
infinite series should be preferred over the other version. I can think of
at least three reasons why the Python behaviour is objectively better,
despite leading to an unwanted infinite loop in this specific case.

(1) The Python version avoids always making a copy of the (potentially huge)
list before looping over it. That makes the performance of for-loops more
predictable and avoids horrible surprises:

for x in L:
    break

takes the same amount of time to execute whether L has one item or a hundred
billion items. The for-loop *overhead* (as opposed to the cost of the loop
itself) is a fixed, small amount.


(2) The Python version has a cleaner, easier to understand execution model.
Apart from two obvious exceptions (on the left hand side of an assignment,
or following the "del" statement) all uses of the name L have the same
meaning. Whether you write:

    for x in L

    if "foo" in L

    while L

    L + [1, 2]

    len(L)

    L or []

    L.append(42)

or any other expression, all uses of the name L evaluate to the same thing:
the object currently bound to that name. You don't have to try to remember
which uses evaluate to the original object and which make a copy. It is
*never* a copy -- if you want a copy, you can copy it yourself. (Use the
copy module, copy.copy(L), or take a slice, L[:].)

The cost of this is that you are always responsible for making a copy, since
Python won't automatically do it for you (whether you want a copy or not).
But the benefit is that you avoid making unnecessary copies. 

I infer from the line "L append:= i" that your language doesn't always make
a copy (otherwise, how could you modify the original?). That means that
you, the programmer, still has to manage the copying of the list, exactly
the same as we have to do with Python. The difference is, Python doesn't
lure you into a false sense of security by *sometimes* making that copy for
you. The rules are:

"In Python, if you want a copy of the list, make a copy yourself."

versus:

"In BartC's language, if you want a copy of the list, look up the operation
you are about to do to see if it already makes a copy, and if it doesn't,
then make a copy yourself. (Otherwise, you might make two copies.)"


(3) What if you don't want a copy? How does one disable that feature? Or
does your language simply declare that "you can't do that"?

for item in queue:
    process(item)
    if condition: queue.append(something)


What's the most natural equivalent to that code snippet in your language?



> The point is that the behaviour of the loop is by no means obvious, so
> neither is the behaviour of the function defaults.

I'm pretty sure that nobody said the behaviour was obvious in the sense of
predictable to those unfamiliar with the rules of the language. There's
even a FAQ about it.

There's a big difference between *obvious in advance* and *obvious in
hindsight once an explanation is given*.



-- 
Steven



From alan at csail.mit.edu  Wed Nov 25 21:08:17 2015
From: alan at csail.mit.edu (Alan Bawden)
Date: Wed, 25 Nov 2015 21:08:17 -0500
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>

Steven D'Aprano <steve at pearwood.info> writes:
> In fact, it's easy to find cases even now where the compiler is
> insufficiently smart to recognise all the possible optimizations available.
> There's no tuple simpler than the empty tuple, but Python 3.3 at least
> fails to optimize that case:
>
> py> dis(compile("()", '', 'eval'))
>   1           0 BUILD_TUPLE              0
>               3 RETURN_VALUE

Actually, it would be silly to compile that as a LOAD_CONST of an empty
tuple.  "BUILD_TUPLE 0" doesn't allocate storage, it returns the same
empty tuple every time!  In effect "BUILD_TUPLE 0" is just a global
load.  A different disassembler might decide to print "BUILD_TUPLE 0" as
"LOAD_EMPTY_TUPLE".

Using LOAD_CONST would just waste space in the function's vector
of constants.

(Note that nothing in the documentation I can find actually _guarantees_
that a Python implementation will only have one unique empty tuple, but
I wouldn't be suprised if the following is nonetheless true in all
current implementations:

   >>> tuple([]) is tuple([])
   True

)

-- 
Alan Bawden


From rosuav at gmail.com  Wed Nov 25 21:25:24 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 13:25:24 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
Message-ID: <CAPTjJmqrEhMR7Uq_V1zPUw6huPjKYPMPDciHvJoCwZDXaSkZfg@mail.gmail.com>

On Thu, Nov 26, 2015 at 1:08 PM, Alan Bawden <alan at csail.mit.edu> wrote:
> (Note that nothing in the documentation I can find actually _guarantees_
> that a Python implementation will only have one unique empty tuple, but
> I wouldn't be suprised if the following is nonetheless true in all
> current implementations:
>
>    >>> tuple([]) is tuple([])
>    True
>
> )

Jython 2.5.3 (, Oct 8 2014, 03:39:09)
[OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_85
Type "help", "copyright", "credits" or "license" for more information.
>>> tuple([]) is tuple([])
False

Python 2.7.8 (2.4.0+dfsg-3, Dec 20 2014, 13:30:46)
[PyPy 2.4.0 with GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>> tuple([]) is tuple([])
False

ChrisA


From ian.g.kelly at gmail.com  Wed Nov 25 21:46:52 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 19:46:52 -0700
Subject: What is a function parameter =[] for?
In-Reply-To: <CAPTjJmqrEhMR7Uq_V1zPUw6huPjKYPMPDciHvJoCwZDXaSkZfg@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <CAPTjJmqrEhMR7Uq_V1zPUw6huPjKYPMPDciHvJoCwZDXaSkZfg@mail.gmail.com>
Message-ID: <CALwzidmFqTWodNxGnJSoeV3wWMvi8dP-6X=dp_kT8m6r=WLcog@mail.gmail.com>

On Wed, Nov 25, 2015 at 7:25 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Thu, Nov 26, 2015 at 1:08 PM, Alan Bawden <alan at csail.mit.edu> wrote:
>> (Note that nothing in the documentation I can find actually _guarantees_
>> that a Python implementation will only have one unique empty tuple, but
>> I wouldn't be suprised if the following is nonetheless true in all
>> current implementations:
>>
>>    >>> tuple([]) is tuple([])
>>    True
>>
>> )
>
> Jython 2.5.3 (, Oct 8 2014, 03:39:09)
> [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_85
> Type "help", "copyright", "credits" or "license" for more information.
>>>> tuple([]) is tuple([])
> False
>
> Python 2.7.8 (2.4.0+dfsg-3, Dec 20 2014, 13:30:46)
> [PyPy 2.4.0 with GCC 4.9.2] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>>> tuple([]) is tuple([])
> False

Well, he did say all "current" implementations. CPython 2.7 may still
be supported, but that doesn't make it current. And anything at 2.5 is
just archaic.


From ian.g.kelly at gmail.com  Wed Nov 25 22:01:43 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Wed, 25 Nov 2015 20:01:43 -0700
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n35l57$ots$1@ger.gmane.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <CAPTjJmoyGi04Dnxxp1AFytLkWQg=D4ccXqE6OwfJJMgp7fg1YA@mail.gmail.com>
 <858u5lc0r7.fsf@benfinney.id.au> <n35l57$ots$1@ger.gmane.org>
Message-ID: <CALwzidkHTUbxYY0cwspJ8jpCEw_BR_WmhqcHaTk3h2gc2XYbSQ@mail.gmail.com>

On Wed, Nov 25, 2015 at 5:52 PM, Random832 <random832 at fastmail.com> wrote:
> On 2015-11-25, Ben Finney <ben+python at benfinney.id.au> wrote:
>> That is, the ?2? in ?cartesian_point = (2, 3)? means something different
>> than in ?cartesian_point = (3, 2)?.
>>
>> Whereas the ?2? in ?test_scores = [2, 3]? means exactly the same as in
>> ?test_scores = [3, 2]?.
>>
>> If each position in the sequence gives the value there a different
>> menaning, use a tuple; if not, use a list.
>
> I don't think that's really right. The absence of first-class
> multisets in python does mean that lists get "abused" for that
> purpose, but I don't think that means that there's no legitimate
> use-case for a list (i.e. a mutable sequence in which position is
> significant).
>
> The difference between a tuple and a list is that one is mutable
> and the other is not. The difference you are describing is
> between a list and a multiset (or a tuple and an immutable
> multiset).

I think that Ben was actually trying to make a distinction between
heterogeneity and homogeneity of the contents, not a distinction of
whether the collection was ordered or not. You can of course have a
homogeneous collection for which order is still important, e.g. a
batting line-up.


From rosuav at gmail.com  Wed Nov 25 22:02:00 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 14:02:00 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidmFqTWodNxGnJSoeV3wWMvi8dP-6X=dp_kT8m6r=WLcog@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547337.4000709@rece.vub.ac.be>
 <CAPTjJmoGt3B_zTVd8dVLHNeanX=4g1yhN-PLpXzZoYiKb9HYuw@mail.gmail.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <CAPTjJmqrEhMR7Uq_V1zPUw6huPjKYPMPDciHvJoCwZDXaSkZfg@mail.gmail.com>
 <CALwzidmFqTWodNxGnJSoeV3wWMvi8dP-6X=dp_kT8m6r=WLcog@mail.gmail.com>
Message-ID: <CAPTjJmq42U+tk_=Za572X0qpihS=+yWcGfMn2keF827jMUeyfw@mail.gmail.com>

On Thu, Nov 26, 2015 at 1:46 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Wed, Nov 25, 2015 at 7:25 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> On Thu, Nov 26, 2015 at 1:08 PM, Alan Bawden <alan at csail.mit.edu> wrote:
>>> (Note that nothing in the documentation I can find actually _guarantees_
>>> that a Python implementation will only have one unique empty tuple, but
>>> I wouldn't be suprised if the following is nonetheless true in all
>>> current implementations:
>>>
>>>    >>> tuple([]) is tuple([])
>>>    True
>>>
>>> )
>>
>> Jython 2.5.3 (, Oct 8 2014, 03:39:09)
>> [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_85
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>> tuple([]) is tuple([])
>> False
>>
>> Python 2.7.8 (2.4.0+dfsg-3, Dec 20 2014, 13:30:46)
>> [PyPy 2.4.0 with GCC 4.9.2] on linux2
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>>> tuple([]) is tuple([])
>> False
>
> Well, he did say all "current" implementations. CPython 2.7 may still
> be supported, but that doesn't make it current. And anything at 2.5 is
> just archaic.

Those are the versions of Jython and PyPy available from the Debian
Jessie repositories. I'm not sure what Jython's compatibility is, but
this is at least reasonably current.

But I grabbed the latest 2.x-compatible PyPy nightly:

Python 2.7.10 (b4515dee6ebf, Nov 25 2015, 23:01:41)
[PyPy 4.1.0-alpha0 with GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
And now for something completely different: ``Every time someone argues with
"Smalltalk has always done X", it is always a good hint that something needs to
be changed fast. - Marcus Denker''
>>>> tuple([]) is tuple([])
False

The latest PyPy3 nightly builds seem to be broken, though; I was
unable to get one to run. The builds compatible with Python 3.2 work,
though:

Python 3.2.5 (b2091e973da6, Oct 19 2014, 18:29:55)
[PyPy 2.4.0 with GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>> tuple([]) is tuple([])
False

So current PyPy still behaves that way.

ChrisA


From alan at csail.mit.edu  Wed Nov 25 23:27:43 2015
From: alan at csail.mit.edu (Alan Bawden)
Date: Wed, 25 Nov 2015 23:27:43 -0500
Subject: What is a function parameter =[] for?
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <56547C53.8030407@rece.vub.ac.be>
 <CAPTjJmqAMwnxBZ97umsNg255v47dsQD6qEr0ysECtGiZ409k0Q@mail.gmail.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
Message-ID: <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>

Chris Angelico <rosuav at gmail.com> writes:

> On Thu, Nov 26, 2015 at 1:08 PM, Alan Bawden <alan at csail.mit.edu> wrote:
>> (Note that nothing in the documentation I can find actually _guarantees_
>> that a Python implementation will only have one unique empty tuple, but
>> I wouldn't be suprised if the following is nonetheless true in all
>> current implementations:
>>
>>    >>> tuple([]) is tuple([])
>>    True
>>
>> )
>
> Jython 2.5.3 (, Oct 8 2014, 03:39:09)
> [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_85
> Type "help", "copyright", "credits" or "license" for more information.
>>>> tuple([]) is tuple([])
> False
>
> Python 2.7.8 (2.4.0+dfsg-3, Dec 20 2014, 13:30:46)
> [PyPy 2.4.0 with GCC 4.9.2] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>>>>> tuple([]) is tuple([])
> False
>
> ChrisA

I said I wouldn't be suprised if it was always true, but that doesn't
imply that I need to be suprised if it is sometimes false!

Having said that, I _am_ curious whether that remains False for various
other variant expressions.  "tuple([])" is actually a rather perverse
way to obtain an empty tuple.  How about plain "() is ()"?  While
"tuple([]) is tuple([])" is False is some implementations, it is still
possible that "() is ()" is True in those same implementations,
depending on how that compiles.

An even more perverse way to obtain an empty tuple is "tuple(x for x in ())"
and in fact in CPython:

   >>> tuple(x for x in ()) is tuple(x for x in ())
   False

If I had thought to try that earlier, I wouldn't have bothered making
the parenthetical remark to are responding to -- because none of this
has any relevance to my original point about "BUILD_TUPLE 0".

-- 
Alan Bawden


From ben+python at benfinney.id.au  Thu Nov 26 00:04:39 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 26 Nov 2015 16:04:39 +1100
Subject: Semantics of collection types (was: Late-binding of function defaults
 (was Re: What is a function parameter =[] for?))
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <CAPTjJmoyGi04Dnxxp1AFytLkWQg=D4ccXqE6OwfJJMgp7fg1YA@mail.gmail.com>
 <858u5lc0r7.fsf@benfinney.id.au> <n35l57$ots$1@ger.gmane.org>
 <CALwzidkHTUbxYY0cwspJ8jpCEw_BR_WmhqcHaTk3h2gc2XYbSQ@mail.gmail.com>
Message-ID: <85wpt59wrc.fsf_-_@benfinney.id.au>

Ian Kelly <ian.g.kelly at gmail.com> writes:

> On Wed, Nov 25, 2015 at 5:52 PM, Random832 <random832 at fastmail.com> wrote:
> > On 2015-11-25, Ben Finney <ben+python at benfinney.id.au> wrote:
> >> That is, the ?2? in ?cartesian_point = (2, 3)? means something
> >> different than in ?cartesian_point = (3, 2)?.
> >>
> >> Whereas the ?2? in ?test_scores = [2, 3]? means exactly the same as
> >> in ?test_scores = [3, 2]?.
> >>
> >> If each position in the sequence gives the value there a different
> >> menaning, use a tuple; if not, use a list.
> >
> > I don't think that's really right.

I was expanding on (by replying to) earlier advice about expressing
semantics in our choice of data types.

> > The difference between a tuple and a list is that one is mutable
> > and the other is not.

That is a difference enforced in the behaviour of the types, yes.

I didn't talk about behaviour, but about meaning. I'm saying that the
behavioural difference conveniently lines up with a semantic difference,
even to the point of the meaning of ?tuple? that pre-dates Python.

> I think that Ben was actually trying to make a distinction between
> heterogeneity and homogeneity of the contents, not a distinction of
> whether the collection was ordered or not.

That's right, thank you.

-- 
 \       ?Nothing exists except atoms and empty space; everything else |
  `\                    is opinion.? ?Democritus, c. 460 BCE ? 370 BCE |
_o__)                                                                  |
Ben Finney



From ben+python at benfinney.id.au  Thu Nov 26 00:08:27 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 26 Nov 2015 16:08:27 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
Message-ID: <85si3t9wl0.fsf@benfinney.id.au>

Ned Batchelder <ned at nedbatchelder.com> writes:

> For someone who claims to be interested in language design, you're
> remarkably dismissive of pretty much the entire industry. I don't
> think it's worth the effort to try to change your mind.

+1.

BartC, when you want to join us in discussions on good faith ? that is,
honestly wanting to learn Python rather than dogmatically persisting in
your misperceptions dogmatically onto it ? we'll still be here, making
happy use of Python the way it is.

-- 
 \       ?Facts are meaningless. You could use facts to prove anything |
  `\                that's even remotely true!? ?Homer, _The Simpsons_ |
_o__)                                                                  |
Ben Finney



From ramjee.ag at gmail.com  Thu Nov 26 01:26:19 2015
From: ramjee.ag at gmail.com (ramjee a.g.)
Date: Thu, 26 Nov 2015 11:56:19 +0530
Subject: Py_NewInterpreter() - Fatal Error with ceval - orphan tstate
Message-ID: <CAGQhfC5ZSZyyL7kmaQmL=ECqCU_Ruy4ytXMYpDeJR=HdKLQ05A@mail.gmail.com>

Hi,

I am using python 2.7 for extending my C++ application with python.

And when two pthread of C is executing Py_NewInterpreter() it is throwing
faltal error with ceval-orphan tstate.  There is no problem when sequential
thread execution.

Let me know if any solution to be fixed in my python library.

Regards,
Ramjee


From breamoreboy at yahoo.co.uk  Thu Nov 26 01:39:38 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 26 Nov 2015 06:39:38 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <85si3t9wl0.fsf@benfinney.id.au>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <85si3t9wl0.fsf@benfinney.id.au>
Message-ID: <n369fe$1dk$1@ger.gmane.org>

On 26/11/2015 05:08, Ben Finney wrote:
> Ned Batchelder <ned at nedbatchelder.com> writes:
>
>> For someone who claims to be interested in language design, you're
>> remarkably dismissive of pretty much the entire industry. I don't
>> think it's worth the effort to try to change your mind.
>
> +1.
>
> BartC, when you want to join us in discussions on good faith ? that is,
> honestly wanting to learn Python rather than dogmatically persisting in
> your misperceptions dogmatically onto it ? we'll still be here, making
> happy use of Python the way it is.
>

Ben and Ned, I'd like to thank both of you for these comments as they 
are put far more eloquently and diplomatically than I would ever manage.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From marko at pacujo.net  Thu Nov 26 01:41:25 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 08:41:25 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
Message-ID: <87si3t2rfu.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:
> Clearly a huge amount of programming can be done without having to deal
> with first-class functions (or constructing functions at run-time; that
> sounds fun). (Or without using OOP, another thing I can't stand.)

Even the lowliest code monkeys deal with on-the-fly functions and OOP
nowadays. You can't escape them in C# and Java, for example.

> Some people just don't want to be functional programmers. It is
> elitist to try and make out it that it is that important.
>
> If lots of languages now have functional features, it's more likely to
> be a case of keeping up with the Joneses.

There's some of that. Generics and closures in Java are examples.

However, anonymous classes have been there in Java since the dawn of
days, and they are equally "elitist" as closures.


Marko


From orgnut at yahoo.com  Thu Nov 26 01:44:41 2015
From: orgnut at yahoo.com (Larry Hudson)
Date: Wed, 25 Nov 2015 22:44:41 -0800
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.56.1448440353.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
Message-ID: <DdSdnUfq3sfHN8vLnZ2dnUU7-XudnZ2d@giganews.com>

On 11/25/2015 12:32 AM, Chris Angelico wrote:
> On Wed, Nov 25, 2015 at 7:14 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> [snip]
>
> "Oh come on. It's basic arithmetic. You should be able to add 7 and
> 7... the result's 14!"
>
> "But it's so confusing. Why can't it be 16? It'd be more convenient
> for me if it were 16."

No.  It's 42.    ;-)

      -=- Larry -=-

<The Hitchhiker's Guide to the Galaxy says that's what *The Answer* is.>



From marko at pacujo.net  Thu Nov 26 01:52:07 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 08:52:07 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <87oaeh2qy0.fsf@elektro.pacujo.net>

Steven D'Aprano <steve at pearwood.info>:

> Making tuples mutable would break their use as dictionary keys, which is a
> *critical* use.

No, it wouldn't. Any object that provides __hash__() and __eq__() can be
used as a key.

Nothing prevents using mutable objects as keys in Python.

    Egon Spengler: There's something very important I forgot to tell you.
    Peter Venkman: What?
    Spengler: Don't use mutable keys.
    Venkman: Why?
    Spengler: It would be bad.
    Venkman: I'm fuzzy on the whole good/bad thing. What do you mean,
       "bad"?
    Spengler: Try to imagine all life as you know it stopping
        instantaneously and every molecule in your body exploding at the
        speed of light.
    Ray Stantz: Total protonic reversal!
    Venkman: Right. That's bad. Okay. All right. Important safety tip.
        Thanks, Egon.


Marko


From Cecil at decebal.nl  Thu Nov 26 01:55:51 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Thu, 26 Nov 2015 07:55:51 +0100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.101.1448491194.20593.python-list@python.org>
Message-ID: <87lh9ldzbc.fsf@Equus.decebal.nl>

On Wednesday 25 Nov 2015 23:39 CET, Zachary Ware wrote:

> On Wed, Nov 25, 2015 at 3:52 PM, Cecil Westerhof <Cecil at decebal.nl> wrote:
>> My system python was all-ready damaged: that is why I wanted to
>> build myself.
>
> Then you should try to repair the system Python install via the
> system package manager. It's not worth the hassle to try to replace
> it; it almost certainly won't work for some strange corner case that
> won't bite you until 3 months from now. It's perfectly OK to have a
> second Python install in /usr/local, even of the same version as the
> system Python.

I tried that. It did install things in /usr/lib and /usr/lib64, but
nothing in /usr/bin. Thought to solve it this way, but I suppose I
have to delve deeper in it.

>> It is an openSUSE system. I installed the readline with:
>> zypper install readline-devel
>>
>> The strange thing is that it does mot compile anymore now. I get:
>> Python build finished, but the necessary bits to build these
>> modules were not found: _bsddb _tkinter bsddb185 dbm dl gdbm
>> imageop sunaudiodev To find the necessary bits, look in setup.py in
>> detect_modules() for the module's name.
>
> Before you installed readline-devel, readline would have been listed
> there as well. It's ok to have modules listed there if you don't

I did not look good the first time then, because I do not remember
having those messages.

But I still get:
    ImportError: No module named readline

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From Cecil at decebal.nl  Thu Nov 26 02:00:58 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Thu, 26 Nov 2015 08:00:58 +0100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
Message-ID: <87h9k9dz2t.fsf@Equus.decebal.nl>

On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:

> In a message of Wed, 25 Nov 2015 22:52:23 +0100, Cecil Westerhof
> writes:
>>
>> My system python was all-ready damaged: that is why I wanted to
>> build myself.
>
> Your Suse system probably wants to use python for something. If your
> system python is damaged, you badly need to fix that, using the
> system package managers tools, before Suse does some sort of update
> on you, using the broken python, which damages more of your system.

I tried that. But it installs only things in /usr/lib and /usr/lib64,
nothing in /usr/bin, but at the same time it is adamant that it
installed python. I wanted a quick fix, but it looks like that is not
going to work. :'-( I'll have to find a way to get things fixed.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From rosuav at gmail.com  Thu Nov 26 02:14:02 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 18:14:02 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87oaeh2qy0.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmpg+Lq8-Y4JErXV1zLXGe-VwfaGrnDtdENMD6OEFzo_UQ@mail.gmail.com>

On Thu, Nov 26, 2015 at 5:52 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Steven D'Aprano <steve at pearwood.info>:
>
>> Making tuples mutable would break their use as dictionary keys, which is a
>> *critical* use.
>
> No, it wouldn't. Any object that provides __hash__() and __eq__() can be
> used as a key.
>
> Nothing prevents using mutable objects as keys in Python.
>
>

Sure, you _can_. But if the key's hash changes between dict insertion
and retrieval, all manner of invariants will break, and likewise if
two equal objects have different hashes. From which you can deduce
logically that any object used as a key must remain (not) equal to
everything that it was (not) equal to from that time until it is
looked up... which basically means its value mustn't change. It must
be immutable.

ChrisA


From dieter at handshake.de  Thu Nov 26 02:17:43 2015
From: dieter at handshake.de (dieter)
Date: Thu, 26 Nov 2015 08:17:43 +0100
Subject: What does a list comprehension do
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de> <5655BCDB.4020905@rece.vub.ac.be>
Message-ID: <877fl5ut48.fsf@handshake.de>

Antoon Pardon <antoon.pardon at rece.vub.ac.be> writes:

> Op 20-11-15 om 08:49 schreef dieter:
>> In addition, the last few days have had two discussions in this list
>> demonstrating the conceptial difficulties of late binding -- one of them:
>>
>>       Why does "[lambda x: i * x for i in range(4)]" gives
>>       a list of essentially the same functions?
>
> Can you (or someone else) explain what a list comprehension is equivallent of.
> Especially in python3.

I am not sure about "Python3" (never used it), but in Python 2,
the simple list comprehension "[x for x in l]" is roughly equivalent to:

    result = []
    for x in l: result.append(x)
    ... the list comprehension result is in "result" which (however) is not bound ...

In Python 3, "x" might not be bound as well - to harmonise list comprehension
with generator expressions (and avoid the confusion, that a local
(temporary) binding can change the value of a global binding).



From antoon.pardon at rece.vub.ac.be  Thu Nov 26 03:15:09 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 09:15:09 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <CALwzidngZMafqiWv-2dZPEsAP+5qVDST2fW0X8i5Y4m0YdJ3Uw@mail.gmail.com>
References: <d9045bdd-a5d4-4c5c-9fd3-3d54f6b50862@googlegroups.com>
 <5654864E.2070906@rece.vub.ac.be>
 <CAPTjJmoUtwHzOEwcObh5hzUDbz-713kVE_Kq-rg_bmYFHE_tYw@mail.gmail.com>
 <56549324.8020607@rece.vub.ac.be>
 <CALwzidmAKgmxjR=nDU4bPn5iy9AqCCiT=nTQYSORADCtpdM+SA@mail.gmail.com>
 <56549F15.40206@rece.vub.ac.be>
 <CALwzidkuiSfyXxiQ8H6YSEtEL5cqj6sOUPXdUru6n8XtGnvzug@mail.gmail.com>
 <5654B037.6020107@rece.vub.ac.be>
 <CALwzidkRj7G-W3UdtdczM10kHmHZ_qrdOoPNcJNjiw2QcNr0YQ@mail.gmail.com>
 <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <5655FDAC.4070305@rece.vub.ac.be>
 <CALwzidkkuQDfGCZUmEDuvLEwLwy27BsDvPaow_LVN_tFYt-1qg@mail.gmail.com>
 <5656229A.2000309@rece.vub.ac.be>
 <CALwzidngZMafqiWv-2dZPEsAP+5qVDST2fW0X8i5Y4m0YdJ3Uw@mail.gmail.com>
Message-ID: <5656BF8D.3050701@rece.vub.ac.be>

Op 25-11-15 om 23:38 schreef Ian Kelly:
> On Wed, Nov 25, 2015 at 2:05 PM, Antoon Pardon
> <antoon.pardon at rece.vub.ac.be> wrote:
>> Op 25-11-15 om 21:39 schreef Ian Kelly:
>>
>>> I believe that sentence from the docs is using "some" to mean "not
>>> all", whereas you are apparently using it to mean "any".
>>>
>>> frozenset([1,2,3]) constructs a constant value of a built-in type.
>>> Would you consider that a literal?
>> I am inclined to say yes, because a sufficient intelligent compilor
>> can compute the value and store it do be retrieved and bound to a
>> target when needed.
> I'm curious then what you think of this:
>
> from collections import namedtuple
>
> class Point(namedtuple("Point", "x y")): pass
>
> Point(17, 12)
>
> Still a constant, but not a built-in type. Would you consider that a literal?

I think I would answer no to that. In this case we have a user class. So
the compilor has no intrinsic knowledge of the structure of this type.
So the language has no choice but to construct the object at the moment
of execution.

-- 
Antoon.



From marko at pacujo.net  Thu Nov 26 03:27:13 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 10:27:13 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
Message-ID: <87a8q1f9ni.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Thu, Nov 26, 2015 at 5:52 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> Nothing prevents using mutable objects as keys in Python.
>
> Sure, you _can_. But if the key's hash changes between dict insertion
> and retrieval, all manner of invariants will break, and likewise if
> two equal objects have different hashes. From which you can deduce
> logically that any object used as a key must remain (not) equal to
> everything that it was (not) equal to from that time until it is
> looked up... which basically means its value mustn't change. It must
> be immutable.

What I'm saying is that Python does not prevent mutable keys but tries
to do that with lists and tuples.

I think Python should stop trying.

I have wanted to use lists as keys, and there should be no reason to
allow mutable tuples. It should be enough to say that the behavior of a
dictionary is undefined if a key should mutate on the fly.


Marko


From steve+comp.lang.python at pearwood.info  Thu Nov 26 03:29:20 2015
From: steve+comp.lang.python at pearwood.info (Steven D'Aprano)
Date: Thu, 26 Nov 2015 19:29:20 +1100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl>
Message-ID: <5656c2e0$0$11120$c3e8da3@news.astraweb.com>

On Thursday 26 November 2015 18:00, Cecil Westerhof wrote:

> On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:
> 
>> In a message of Wed, 25 Nov 2015 22:52:23 +0100, Cecil Westerhof
>> writes:
>>>
>>> My system python was all-ready damaged: that is why I wanted to
>>> build myself.
>>
>> Your Suse system probably wants to use python for something. If your
>> system python is damaged, you badly need to fix that, using the
>> system package managers tools, before Suse does some sort of update
>> on you, using the broken python, which damages more of your system.
> 
> I tried that. But it installs only things in /usr/lib and /usr/lib64,
> nothing in /usr/bin, but at the same time it is adamant that it
> installed python. I wanted a quick fix, but it looks like that is not
> going to work. :'-( I'll have to find a way to get things fixed.
> 

On the assumption that you are more interested in fixing your broken system 
than learning how to compile Python, what happens if you use the Suse 
package manager to re-install Python?

e.g. zypper python

or equivalent.



-- 
Steve



From antoon.pardon at rece.vub.ac.be  Thu Nov 26 03:31:55 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 09:31:55 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
Message-ID: <5656C37B.4020801@rece.vub.ac.be>

Op 26-11-15 om 02:52 schreef Ned Batchelder:
> I almost started to explain about how yes, Python is often written in
> conservative static ways. I was going to mention that a little dynamic
> nature goes a long way, and is never far from the surface in even the
> simplest Python programs.
>
> But I won't, because I'm not sure you're really interested.  There's a
> pattern here of people trying to explain Python to you, and eventually,
> after many words, getting to some kind of shared understanding, only
> for you to shrug it all off as a fad, or pocket-lining, or needless
> complexity.
>
> For someone who claims to be interested in language design, you're
> remarkably dismissive of pretty much the entire industry.  I don't think
> it's worth the effort to try to change your mind.

I agree. I still think the regulars tend to react in a too defensive way
when someone rather new dares to find fault with some python aspects. But
if someone comes here and can't get over their bizarre first impression of 
some python aspects then there is not much reason to continue the discussion
with them either.

-- 
Antoon.



From rosuav at gmail.com  Thu Nov 26 03:34:47 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 19:34:47 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87a8q1f9ni.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrc23hSo7Z7B42M0G2QV+VOFNon5O=nbGbxPThg4rw3hA@mail.gmail.com>

On Thu, Nov 26, 2015 at 7:27 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Thu, Nov 26, 2015 at 5:52 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> Nothing prevents using mutable objects as keys in Python.
>>
>> Sure, you _can_. But if the key's hash changes between dict insertion
>> and retrieval, all manner of invariants will break, and likewise if
>> two equal objects have different hashes. From which you can deduce
>> logically that any object used as a key must remain (not) equal to
>> everything that it was (not) equal to from that time until it is
>> looked up... which basically means its value mustn't change. It must
>> be immutable.
>
> What I'm saying is that Python does not prevent mutable keys but tries
> to do that with lists and tuples.
>
> I think Python should stop trying.
>
> I have wanted to use lists as keys, and there should be no reason to
> allow mutable tuples. It should be enough to say that the behavior of a
> dictionary is undefined if a key should mutate on the fly.

Python defines dict-key-validity as being synonymous with hashability.
It's up to the class author to make sure the object's hash is useful.

Behaviour being undefined works just fine [1] in C. It's not so
popular in Python. I don't think we want to have myriad new and
experienced programmers trying to figure out why square brackets in
dict keys are usually fine but occasionally not.

ChrisA

[1] For some definition of "fine", anyway.


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 03:45:46 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 09:45:46 +0100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87a8q1f9ni.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
Message-ID: <5656C6BA.50404@rece.vub.ac.be>

Op 26-11-15 om 09:27 schreef Marko Rauhamaa:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Thu, Nov 26, 2015 at 5:52 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> Nothing prevents using mutable objects as keys in Python.
>> Sure, you _can_. But if the key's hash changes between dict insertion
>> and retrieval, all manner of invariants will break, and likewise if
>> two equal objects have different hashes. From which you can deduce
>> logically that any object used as a key must remain (not) equal to
>> everything that it was (not) equal to from that time until it is
>> looked up... which basically means its value mustn't change. It must
>> be immutable.
> What I'm saying is that Python does not prevent mutable keys but tries
> to do that with lists and tuples.
>
> I think Python should stop trying.
>
> I have wanted to use lists as keys, and there should be no reason to
> allow mutable tuples. It should be enough to say that the behavior of a
> dictionary is undefined if a key should mutate on the fly.

Maybe python could introduce a dictionary that copies the keys in and
out the dictionary. In that case keys can be mutable without that being
a problem for the dictionary, because the dictionary works with it's own
copy of the key that it doesn't mutate.

-- 
Antoon.



From rxjwg98 at gmail.com  Thu Nov 26 04:02:19 2015
From: rxjwg98 at gmail.com (fl)
Date: Thu, 26 Nov 2015 01:02:19 -0800 (PST)
Subject: Question about output different with command dis.dis(code)
Message-ID: <f0dc1c2c-6fda-4bd8-a71b-29db358afe14@googlegroups.com>

Hi,

I see the following from a previous post:


Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat 
4.1.2-52)] on linux2 
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam 
>>> import dis 
>>> code = compile("(1, 2, 3)", "", "eval") 
>>> dis.dis(code) 
          0 SET_LINENO          0 
          3 LOAD_CONST          0 (1) 
          6 LOAD_CONST          1 (2) 
          9 LOAD_CONST          2 (3) 
         12 BUILD_TUPLE         3 
         15 RETURN_VALUE 


When I run the above three line code, I get the following:

dis.dis(code)
  1           0 LOAD_CONST               3 ((1, 2, 3))
              3 RETURN_VALUE        


on my Windows 7 PC Canopy. Are there something, my input or Python difference
make the output different?

Thanks,


From rosuav at gmail.com  Thu Nov 26 04:09:30 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 20:09:30 +1100
Subject: Question about output different with command dis.dis(code)
In-Reply-To: <f0dc1c2c-6fda-4bd8-a71b-29db358afe14@googlegroups.com>
References: <f0dc1c2c-6fda-4bd8-a71b-29db358afe14@googlegroups.com>
Message-ID: <CAPTjJmq1===o30TftEd+uRgw6=fWMmpCrtsRh2pvDPp4yB9htw@mail.gmail.com>

On Thu, Nov 26, 2015 at 8:02 PM, fl <rxjwg98 at gmail.com> wrote:
> Are there something, my input or Python difference
> make the output different?

Anything involving the disassembly of Python code depends heavily on
internal interpreter details. You just quoted something showing that
ancient versions of Python did at run-time what current versions have
optimized to a compile-time construction (and thus the quick
LOAD_CONST instead of the full work of building the tuple). If you
switch to PyPy, Jython, IronPython, or some other implementation of
the language, the byte code may be completely different - or may not
be available at all. Using dis.dis is a great way of finding out what
is actually happening, but it's never something you can depend on the
stability of.

ChrisA


From random832 at fastmail.com  Thu Nov 26 04:12:39 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 26 Nov 2015 04:12:39 -0500
Subject: Question about output different with command dis.dis(code)
References: <f0dc1c2c-6fda-4bd8-a71b-29db358afe14@googlegroups.com>
Message-ID: <m2lh9l86pk.fsf@fastmail.com>

fl <rxjwg98 at gmail.com> writes:
> Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat 
> 4.1.2-52)] on linux2

The context of the post was discussing the behavior of a
very old version of python. I'm not sure how you missed
this.

> When I run the above three line code, I get the following:

Further down in the same post you saw, he mentioned that
modern versions of python do this, and showed the same
output that you have.



From df at see.replyto.invalid  Thu Nov 26 05:34:43 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Thu, 26 Nov 2015 10:34:43 +0000
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
Message-ID: <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>

Alan Bawden <alan at csail.mit.edu> wrote:

>Chris Angelico <rosuav at gmail.com> writes:
> ...
>> Python 2.7.8 (2.4.0+dfsg-3, Dec 20 2014, 13:30:46)
>> [PyPy 2.4.0 with GCC 4.9.2] on linux2
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>>> tuple([]) is tuple([])
>> False
>
>I said I wouldn't be suprised if it was always true, but that doesn't
>imply that I need to be suprised if it is sometimes false!
>
>Having said that, I _am_ curious whether that remains False for various
>other variant expressions.  "tuple([])" is actually a rather perverse
>way to obtain an empty tuple.  How about plain "() is ()"? ...

Still false in PyPy it seems

[PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>> id(())
139836165383760L
>>>> id(())
139836165383776L

(Conversely, I see that unlike CPython, all PyPy's numbers have
unchanging ids, even after exiting PyPy and restarting, so it seems that
PyPy's numerical ids are "faked".)

[PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>> id(1+2j)
679900119843984469027190799480815353863L

[PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>> id(1+2j)
679900119843984469027190799480815353863L


From marko at pacujo.net  Thu Nov 26 05:54:05 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 12:54:05 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
Message-ID: <87610pf2uq.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Thu, Nov 26, 2015 at 7:27 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> I have wanted to use lists as keys, and there should be no reason to
>> allow mutable tuples. It should be enough to say that the behavior of
>> a dictionary is undefined if a key should mutate on the fly.
>
> Python defines dict-key-validity as being synonymous with hashability.
> It's up to the class author to make sure the object's hash is useful.

   >>> hash([])
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   TypeError: unhashable type: 'list'

Annoying.

> Behaviour being undefined works just fine [1] in C. It's not so
> popular in Python. I don't think we want to have myriad new and
> experienced programmers trying to figure out why square brackets in
> dict keys are usually fine but occasionally not.

But there's no way to enforce that with any of the myriad new classes.

   Ye blind guides, which strain at a gnat, and swallow a camel.

But I say unto you, Swallow the gnat as well.


Marko


From marko at pacujo.net  Thu Nov 26 05:58:07 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 12:58:07 +0200
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
Message-ID: <871tbdf2o0.fsf@elektro.pacujo.net>

Dave Farrance <df at see.replyto.invalid>:

> (Conversely, I see that unlike CPython, all PyPy's numbers have
> unchanging ids, even after exiting PyPy and restarting, so it seems
> that PyPy's numerical ids are "faked".)

What's a faked id?


Marko


From rosuav at gmail.com  Thu Nov 26 06:04:06 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 22:04:06 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87610pf2uq.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
 <87610pf2uq.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmoJSsbdTA=CUL+NPkv8=XL4UVpuStcoLXXoYM6maZnT2g@mail.gmail.com>

On Thu, Nov 26, 2015 at 9:54 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Thu, Nov 26, 2015 at 7:27 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>> I have wanted to use lists as keys, and there should be no reason to
>>> allow mutable tuples. It should be enough to say that the behavior of
>>> a dictionary is undefined if a key should mutate on the fly.
>>
>> Python defines dict-key-validity as being synonymous with hashability.
>> It's up to the class author to make sure the object's hash is useful.
>
>    >>> hash([])
>    Traceback (most recent call last):
>      File "<stdin>", line 1, in <module>
>    TypeError: unhashable type: 'list'
>
> Annoying.

Yes, it's really annoying that you get an immediate exception instead
of unpredictably getting bizarre failures that depend on the exact
bucket sizes and dict size and so on. It's such a pain to get told
exactly where the problem is.

>> Behaviour being undefined works just fine [1] in C. It's not so
>> popular in Python. I don't think we want to have myriad new and
>> experienced programmers trying to figure out why square brackets in
>> dict keys are usually fine but occasionally not.
>
> But there's no way to enforce that with any of the myriad new classes.

Python tends to assume that programmers are intelligent people who are
prepared to fix their mistakes. As a general rule, if you define
__eq__, you should probably define __hash__ as well, and then you need
to know what you're doing; specifically, the invariant that if a==b,
hash(a)==hash(b). Python doesn't enforce that because it's impossible
to enforce.

ChrisA


From df at see.replyto.invalid  Thu Nov 26 06:07:06 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Thu, 26 Nov 2015 11:07:06 +0000
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl>
Message-ID: <pdpd5b9nn14apgog6pie58lhr2ivfo9i57@4ax.com>

Cecil Westerhof <Cecil at decebal.nl> wrote:

>On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:
>>
>> Your Suse system probably wants to use python for something. If your
>> system python is damaged, you badly need to fix that, using the
>> system package managers tools, before Suse does some sort of update
>> on you, using the broken python, which damages more of your system.
>
>I tried that. But it installs only things in /usr/lib and /usr/lib64,
>nothing in /usr/bin, but at the same time it is adamant that it
>installed python. I wanted a quick fix, but it looks like that is not
>going to work. :'-( I'll have to find a way to get things fixed.

A complete reinstall of Suse (after saving your home directory and work)
might be quickest if you're in the dark about what's broken.

But you might be able to fix it.  If you can figure out which packages
contain the damaged files, then do forced reinstalls of those.  I've not
used Suse, but a quick Google tells me that the syntax is:

zypper in -f <package-name>

So you'll want to try package names like "python" and "python2.7".


From df at see.replyto.invalid  Thu Nov 26 06:12:03 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Thu, 26 Nov 2015 11:12:03 +0000
Subject: What is a function parameter =[] for?
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
Message-ID: <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>

Marko Rauhamaa <marko at pacujo.net> wrote:

>Dave Farrance <df at see.replyto.invalid>:
>
>> (Conversely, I see that unlike CPython, all PyPy's numbers have
>> unchanging ids, even after exiting PyPy and restarting, so it seems
>> that PyPy's numerical ids are "faked".)
>
>What's a faked id?

You can figure out what I'm getting at -- i.e. I presume that the ids
are not pointers to stored numbers in memory (as with CPython) but are a
translation of the numerical variable's value.


From nobody at nowhere.invalid  Thu Nov 26 06:13:44 2015
From: nobody at nowhere.invalid (Nobody)
Date: Thu, 26 Nov 2015 11:13:44 +0000
Subject: What does a list comprehension do (was: Late-binding of function
 defaults (was Re: What is a function parameter =[] for?))
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
Message-ID: <pan.2015.11.26.11.13.43.440000@nowhere.invalid>

On Wed, 25 Nov 2015 14:51:23 +0100, Antoon Pardon wrote:

> Am I missing something?

The issue is with lambdas rather than with list comprehensions per se.

Python's lambdas capture free variables by reference, not value.

	> x = 3
	> f = lambda y: x + y
	> f(0)
	3
	> x = 7
	> f(0)
	7

The same issue applies to nested functions:

	> def foo():
	=    x = 3
	=    def f(y):
	=       return x + y
	=    print f(0)
	=    x = 7
	=    print f(0)
	= 
	> foo()
	3
	7

And also to non-nested functions (but most people expect that):

	> x = 3
	> def f(y,x=x):
	=   return x + y
	=
	> print f(0)
	3
	> x=7
	> print f(0)
	3

If you want to capture a variable by value, add a parameter with a default
value using that variable:

	> def foo():
	=    x = 3
	=    def f(y, x=x):
	=       return x + y
	=    print f(0)
	=    x = 7
	=    print f(0)
	= 
	> foo()
	3
	3

This also works for lambdas:

	> x = 3
	> f = lambda y,x=x: x + y
	> f(0)
	3
	> x = 7
	> f(0)
	3

Returning to the original expression:

	> q = [lambda x: i * x for i in range(4)]
	> q[0](1), q[3](1)
	(3, 3)
	> q = [lambda x,i=i: i * x for i in range(4)]
	> q[0](1), q[3](1)
	(0, 3)




From breamoreboy at yahoo.co.uk  Thu Nov 26 06:17:56 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 26 Nov 2015 11:17:56 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87oaeh2qy0.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
Message-ID: <n36pp8$82f$1@ger.gmane.org>

On 26/11/2015 06:52, Marko Rauhamaa wrote:
> Steven D'Aprano <steve at pearwood.info>:
>
>> Making tuples mutable would break their use as dictionary keys, which is a
>> *critical* use.
>
> No, it wouldn't. Any object that provides __hash__() and __eq__() can be
> used as a key.
>

Almost, see https://wiki.python.org/moin/DictionaryKeys.  Under the 
title "Types Usable as Dictionary Keys" it states "The discussion above 
should explain why Python requires that:

To be used as a dictionary key, an object must support the hash function 
(e.g. through __hash__), equality comparison (e.g. through __eq__ or 
__cmp__), and must satisfy the correctness condition above."

The correctness condition is:-

"For such a lookup algorithm to work correctly, the hash functions 
provided must guarantee that if two keys produce different hash values 
then the two key objects are not equivalent, that is,

for all i1, i2, if hash(i1) != hash(i2), then i1 != i2"

Aren't search engines just wonderful :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From marko at pacujo.net  Thu Nov 26 06:23:23 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 13:23:23 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
 <87610pf2uq.fsf@elektro.pacujo.net>
 <mailman.127.1448535849.20593.python-list@python.org>
Message-ID: <87wpt5dmxg.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Thu, Nov 26, 2015 at 9:54 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>
>>    >>> hash([])
>>    Traceback (most recent call last):
>>      File "<stdin>", line 1, in <module>
>>    TypeError: unhashable type: 'list'
>>
>> Annoying.
>
> Yes, it's really annoying that you get an immediate exception instead
> of unpredictably getting bizarre failures that depend on the exact
> bucket sizes and dict size and so on. It's such a pain to get told
> exactly where the problem is.

The problem is that lists don't have __hash__ and __eq__ defined.

> Python tends to assume that programmers are intelligent people who are
> prepared to fix their mistakes.

It's not letting me in the case of list.


Marko


From ben+python at benfinney.id.au  Thu Nov 26 06:24:25 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Thu, 26 Nov 2015 22:24:25 +1100
Subject: Object identity has no necessary connection to memory location (was:
 What is a function parameter =[] for?)
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
Message-ID: <85lh9l9f6e.fsf_-_@benfinney.id.au>

Dave Farrance <df at see.replyto.invalid> writes:

> Marko Rauhamaa <marko at pacujo.net> wrote:
>
> >Dave Farrance <df at see.replyto.invalid>:
> >
> >> (Conversely, I see that unlike CPython, all PyPy's numbers have
> >> unchanging ids, even after exiting PyPy and restarting, so it seems
> >> that PyPy's numerical ids are "faked".)
> >
> >What's a faked id?
>
> You can figure out what I'm getting at -- i.e. I presume that the ids
> are not pointers to stored numbers in memory (as with CPython) but are
> a translation of the numerical variable's value.

Why refer to that as ?faked?? That's what I can't figure out about what
you're getting at. Perhaps Marko shares my uncomprehension.

The Python language makes no promise about ?pointers to stored numbers
in memory? for object identity. That is an implementation detail of
CPython, and is *explicitly* not promised for any other Python
implementation.

If you are surprised that object identity appears to have no connection
with memory location, then you've made unwarranted assumptions that are
explicitly warned against in the Python documentation.

-- 
 \        ?Absurdity, n. A statement or belief manifestly inconsistent |
  `\            with one's own opinion.? ?Ambrose Bierce, _The Devil's |
_o__)                                                Dictionary_, 1906 |
Ben Finney



From rosuav at gmail.com  Thu Nov 26 06:24:44 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 22:24:44 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
Message-ID: <CAPTjJmo0g7ssCxyiKdMffS-fRQ+03ataD-DOLjyJNH68PkUohA@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:12 PM, Dave Farrance <df at see.replyto.invalid> wrote:
> Marko Rauhamaa <marko at pacujo.net> wrote:
>
>>Dave Farrance <df at see.replyto.invalid>:
>>
>>> (Conversely, I see that unlike CPython, all PyPy's numbers have
>>> unchanging ids, even after exiting PyPy and restarting, so it seems
>>> that PyPy's numerical ids are "faked".)
>>
>>What's a faked id?
>
> You can figure out what I'm getting at -- i.e. I presume that the ids
> are not pointers to stored numbers in memory (as with CPython) but are a
> translation of the numerical variable's value.

As long as they're unique among concurrently-existing objects, that's
fully compliant and not at all invalid. It might be generated in some
way from its value, but that's safe as long as there's a scheme that
keeps all other objects away from them.

ChrisA


From marko at pacujo.net  Thu Nov 26 06:27:42 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 13:27:42 +0200
Subject: What is a function parameter =[] for?
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
Message-ID: <87si3tdmq9.fsf@elektro.pacujo.net>

Dave Farrance <df at see.replyto.invalid>:

> Marko Rauhamaa <marko at pacujo.net> wrote:
>>What's a faked id?
>
> You can figure out what I'm getting at -- i.e. I presume that the ids
> are not pointers to stored numbers in memory (as with CPython) but are
> a translation of the numerical variable's value.

CPython is within its rights to fake the ids.


Marko


From rosuav at gmail.com  Thu Nov 26 06:35:54 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 22:35:54 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87wpt5dmxg.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
 <87610pf2uq.fsf@elektro.pacujo.net>
 <mailman.127.1448535849.20593.python-list@python.org>
 <87wpt5dmxg.fsf@elektro.pacujo.net>
Message-ID: <CAPTjJmrYRP1C51WWtXkTC7MS2rNHE8=N68VWodTJc2V3iuZXpQ@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:23 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
> Chris Angelico <rosuav at gmail.com>:
>
>> On Thu, Nov 26, 2015 at 9:54 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>>
>>>    >>> hash([])
>>>    Traceback (most recent call last):
>>>      File "<stdin>", line 1, in <module>
>>>    TypeError: unhashable type: 'list'
>>>
>>> Annoying.
>>
>> Yes, it's really annoying that you get an immediate exception instead
>> of unpredictably getting bizarre failures that depend on the exact
>> bucket sizes and dict size and so on. It's such a pain to get told
>> exactly where the problem is.
>
> The problem is that lists don't have __hash__ and __eq__ defined.

They do define equality. And it depends on their contents, ergo there
cannot be a stable hash. This is NOT a problem. This is the concept of
unhashability behaving EXACTLY CORRECTLY. Sorry to shout, but this is
another case of refusing to accept what has been explained as having
good reason, and I'm getting a little tired of it.

>> Python tends to assume that programmers are intelligent people who are
>> prepared to fix their mistakes.
>
> It's not letting me in the case of list.

Actually it is. Your mistake is trying to use a list as a dict key.
You have a solution available: use a tuple.

ChrisA


From rosuav at gmail.com  Thu Nov 26 06:49:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Thu, 26 Nov 2015 22:49:14 +1100
Subject: Object identity has no necessary connection to memory location
 (was: What is a function parameter =[] for?)
In-Reply-To: <85lh9l9f6e.fsf_-_@benfinney.id.au>
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <85lh9l9f6e.fsf_-_@benfinney.id.au>
Message-ID: <CAPTjJmrBbJ8mo8LcdGywe256AEKt1QqGpGVk49nvTwPjXiWS9w@mail.gmail.com>

On Thu, Nov 26, 2015 at 10:24 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Dave Farrance <df at see.replyto.invalid> writes:
>
>> Marko Rauhamaa <marko at pacujo.net> wrote:
>>
>> >Dave Farrance <df at see.replyto.invalid>:
>> >
>> >> (Conversely, I see that unlike CPython, all PyPy's numbers have
>> >> unchanging ids, even after exiting PyPy and restarting, so it seems
>> >> that PyPy's numerical ids are "faked".)
>> >
>> >What's a faked id?
>>
>> You can figure out what I'm getting at -- i.e. I presume that the ids
>> are not pointers to stored numbers in memory (as with CPython) but are
>> a translation of the numerical variable's value.
>
> Why refer to that as ?faked?? That's what I can't figure out about what
> you're getting at. Perhaps Marko shares my uncomprehension.
>
> The Python language makes no promise about ?pointers to stored numbers
> in memory? for object identity. That is an implementation detail of
> CPython, and is *explicitly* not promised for any other Python
> implementation.
>
> If you are surprised that object identity appears to have no connection
> with memory location, then you've made unwarranted assumptions that are
> explicitly warned against in the Python documentation.

I can't remember which language it was (maybe Lua?), but I know
there's one that uses a machine word to store either a pointer to a
heap object, or an integer of at most one less bit than the machine
word, represented by 2*n+1. A system like this would work for Python
object IDs; it guarantees that all heap objects have unique even IDs
(because no two can share the same address; all it takes is requiring
16-bit alignment, and most modern CPUs will give at least 32-bit), and
all small integers will be slotted in between them. So the integer
objects might themselves be entirely faked, never actually existing in
memory, yet never violating the rule of object IDs. (Any integer too
big to fit in a machine word minus one bit would be heap-allocated, so
they're safe.)

That's "faked", in a sense, but still perfectly compliant.

ChrisA


From df at see.replyto.invalid  Thu Nov 26 06:50:15 2015
From: df at see.replyto.invalid (Dave Farrance)
Date: Thu, 26 Nov 2015 11:50:15 +0000
Subject: Object identity has no necessary connection to memory location
 (was: What is a function parameter =[] for?)
References: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <mailman.129.1448537076.20593.python-list@python.org>
Message-ID: <1esd5bdujvog21u4qu6llhna5c3d573873@4ax.com>

Ben Finney <ben+python at benfinney.id.au> wrote:

>Dave Farrance <df at see.replyto.invalid> writes:
>
>> Marko Rauhamaa <marko at pacujo.net> wrote:
>>
>> >Dave Farrance <df at see.replyto.invalid>:
>> >
>> >> (Conversely, I see that unlike CPython, all PyPy's numbers have
>> >> unchanging ids, even after exiting PyPy and restarting, so it seems
>> >> that PyPy's numerical ids are "faked".)
>> >
>> >What's a faked id?
>>
>> You can figure out what I'm getting at -- i.e. I presume that the ids
>> are not pointers to stored numbers in memory (as with CPython) but are
>> a translation of the numerical variable's value.
>
>Why refer to that as ?faked?? That's what I can't figure out about what
>you're getting at. Perhaps Marko shares my uncomprehension.

Hence

https://en.wikipedia.org/wiki/Scare_quotes


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 06:52:45 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 12:52:45 +0100
Subject: What does a list comprehension do
In-Reply-To: <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
Message-ID: <5656F28D.80803@rece.vub.ac.be>

Op 26-11-15 om 12:13 schreef Nobody:
> Returning to the original expression:
>
> 	> q = [lambda x: i * x for i in range(4)]
> 	> q[0](1), q[3](1)
> 	(3, 3)
> 	> q = [lambda x,i=i: i * x for i in range(4)]
> 	> q[0](1), q[3](1)
> 	(0, 3)

Personnaly I would prefer:

>>> q = [(lambda i: lambda x: i * x)(i) for i in range(4)]
>>> q[0](1), q[3](1)
(0, 3)

And this is where I ask whether it would be worth the effort to change
the behaviour of python.

In general the following two seem equivallent:

   [<expression> for x in <iter>] and [(lambda x: <expression>)(x) for x in <iter>]

The only exceptions seems to be when <expression> is itself a lambda.

It also seems that people who try this for the first time are surprised
with what they get and seem to expect there list comprehension to
act as if they had written the second version.

So would it be advisable if python would translate the expression people
write into a lambda that gets called?

Are there issues that could come up?



From marko at pacujo.net  Thu Nov 26 07:03:47 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 14:03:47 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
 <87610pf2uq.fsf@elektro.pacujo.net>
 <mailman.127.1448535849.20593.python-list@python.org>
 <87wpt5dmxg.fsf@elektro.pacujo.net>
 <mailman.131.1448537758.20593.python-list@python.org>
Message-ID: <87oaehdl24.fsf@elektro.pacujo.net>

Chris Angelico <rosuav at gmail.com>:

> On Thu, Nov 26, 2015 at 10:23 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>> It's not letting me in the case of list.
>
> Actually it is. Your mistake is trying to use a list as a dict key.
> You have a solution available: use a tuple.

Yes, or wrap the list in a class.


Marko


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 07:04:54 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 13:04:54 +0100
Subject: Object identity has no necessary connection to memory location
In-Reply-To: <CAPTjJmrBbJ8mo8LcdGywe256AEKt1QqGpGVk49nvTwPjXiWS9w@mail.gmail.com>
References: <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <85lh9l9f6e.fsf_-_@benfinney.id.au>
 <CAPTjJmrBbJ8mo8LcdGywe256AEKt1QqGpGVk49nvTwPjXiWS9w@mail.gmail.com>
Message-ID: <5656F566.6010306@rece.vub.ac.be>

Op 26-11-15 om 12:49 schreef Chris Angelico:
> I can't remember which language it was (maybe Lua?), but I know
> there's one that uses a machine word to store either a pointer to a
> heap object, or an integer of at most one less bit than the machine
> word, represented by 2*n+1.

I think that was smalltalk.



From python at mrabarnett.plus.com  Thu Nov 26 07:36:21 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 26 Nov 2015 12:36:21 +0000
Subject: Looking for ideas to improve library API
In-Reply-To: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
References: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
Message-ID: <5656FCC5.9000308@mrabarnett.plus.com>

On 2015-11-25 20:52, Chris Lalancette wrote:
> Hello,
>       I'm currently developing a library called pyiso (
> https://github.com/clalancette/pyiso), used for manipulating ISO disk
> images.  I'm pretty far along with it, but there is one part of the API
> that I really don't like.
>      Typical usage of the library is something like:
>
> import pyiso
>
> p = pyiso.PyIso() // create the object
> f = open('/path/to/original.iso', 'r')
> p.open(f)  // parse all of the metadata from the input ISO
> fp = open('/path/to/file/to/add/to/iso', 'r')
> p.add_fp(fp)  // add a new file to the ISO
> out = open('/path/to/modified.iso', 'w')
> p.write(out)  // write out the modified ISO to another file
> out.close()
> fp.close()
> f.close()
>
> This currently works OK.  The problem ends up being the file descriptor
> lifetimes.  I want the user to be able to do multiple operations to the
> ISO, and I also don't want to read the entire ISO (and new files) into
> memory.  That means that internal to the library, I take a reference to the
> file object that the user passes in during open() and add_fp().  This is
> fine, unless the user decides to close the file object before calling the
> write method, at which point the write complains of I/O to a closed file.
> This is especially problematic when it comes to using context managers,
> since the user needs to leave the context open until they call write().
>        I've thought of a couple ways to deal with this:
>
> 1.  Make a copy of the file object internal to the library, using os.dup()
> to copy the file descriptor.  This is kind of nasty, especially since I
> want to support other kinds of file objects (think StringIO).
> 2.  Just document the fact that the user needs to leave the file objects
> open until they are done.  This is simple, but not super user-friendly.
>
> I'm looking for any ideas of how to do this better, or something I missed.
> Any input is appreciated!
>
Why pass a file descriptor? Why not a filename?



From jeanpierreda at gmail.com  Thu Nov 26 07:46:34 2015
From: jeanpierreda at gmail.com (Devin Jeanpierre)
Date: Thu, 26 Nov 2015 04:46:34 -0800
Subject: Looking for ideas to improve library API
In-Reply-To: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
References: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
Message-ID: <CABicbJJkNCTW6PAWw_P5mQmHAwysJaG49N8C+zLV9vKQkWB8_Q@mail.gmail.com>

Why not take ownership of the file object, instead of requiring users
to manage lifetimes?

-- Devin

On Wed, Nov 25, 2015 at 12:52 PM, Chris Lalancette
<clalancette at gmail.com> wrote:
> Hello,
>      I'm currently developing a library called pyiso (
> https://github.com/clalancette/pyiso), used for manipulating ISO disk
> images.  I'm pretty far along with it, but there is one part of the API
> that I really don't like.
>     Typical usage of the library is something like:
>
> import pyiso
>
> p = pyiso.PyIso() // create the object
> f = open('/path/to/original.iso', 'r')
> p.open(f)  // parse all of the metadata from the input ISO
> fp = open('/path/to/file/to/add/to/iso', 'r')
> p.add_fp(fp)  // add a new file to the ISO
> out = open('/path/to/modified.iso', 'w')
> p.write(out)  // write out the modified ISO to another file
> out.close()
> fp.close()
> f.close()
>
> This currently works OK.  The problem ends up being the file descriptor
> lifetimes.  I want the user to be able to do multiple operations to the
> ISO, and I also don't want to read the entire ISO (and new files) into
> memory.  That means that internal to the library, I take a reference to the
> file object that the user passes in during open() and add_fp().  This is
> fine, unless the user decides to close the file object before calling the
> write method, at which point the write complains of I/O to a closed file.
> This is especially problematic when it comes to using context managers,
> since the user needs to leave the context open until they call write().
>       I've thought of a couple ways to deal with this:
>
> 1.  Make a copy of the file object internal to the library, using os.dup()
> to copy the file descriptor.  This is kind of nasty, especially since I
> want to support other kinds of file objects (think StringIO).
> 2.  Just document the fact that the user needs to leave the file objects
> open until they are done.  This is simple, but not super user-friendly.
>
> I'm looking for any ideas of how to do this better, or something I missed.
> Any input is appreciated!
>
> Thanks,
> Chris Lalancette
> --
> https://mail.python.org/mailman/listinfo/python-list


From bc at freeuk.com  Thu Nov 26 07:53:27 2015
From: bc at freeuk.com (BartC)
Date: Thu, 26 Nov 2015 12:53:27 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
Message-ID: <n36v80$1nt$1@dont-email.me>

On 26/11/2015 01:52, Ned Batchelder wrote:
> On Wednesday, November 25, 2015 at 8:23:36 PM UTC-5, BartC wrote:
>> On 26/11/2015 00:31, Steven D'Aprano wrote:

>>> It really, truly isn't. Your viewpoint is clouded by too much immersion in
>>> crippled languages. *Old and obsolete versions* of crippled languages.
>>> Dynamic creation of functions goes back to the 1950s.

>> It's funny then that the vast majority of top-level function definitions
>> I see in Python (and import and class statements too) are decidedly static.

> I almost started to explain about how yes, Python is often written in
> conservative static ways. I was going to mention that a little dynamic
> nature goes a long way, and is never far from the surface in even the
> simplest Python programs.
>
> But I won't, because I'm not sure you're really interested.  There's a
> pattern here of people trying to explain Python to you, and eventually,
> after many words, getting to some kind of shared understanding, only
> for you to shrug it all off as a fad, or pocket-lining, or needless
> complexity.

I'm sorry if I've been misunderstood.

I simply stated that Python's approach was novel. Steven D'Aprano then 
responded by belittling my view, and effectively trashing every language 
I've ever used.

But as it happens I do think features like first class functions are 
overrated (and probably the software underpinning the hardware we're all 
using is written in the very languages he despises). I don't think a 
language is worthless without such a feature.

 > For someone who claims to be interested in language design, you're
 > remarkably dismissive of pretty much the entire industry.  I don't think
 > it's worth the effort to try to change your mind.

I did say somewhere in this thread or the other one, that I liked 
Python's model well enough that I tried to emulate it in my own 
language. That's not being dismissive! (It don't work because the 
languages are too different internally; I'll have to save it for a 
separate, higher-level language.)

Also, as an implementer, you can understand that I might view certain 
features differently from other people. Dynamic features do make it 
harder to implement things efficiently, and you have to decide whether 
it's worthwhile for the 1% of the time they might be used.

------------------------------------------

FWIW here is that list of features that are different between Python and 
my language, or that work a different way, or that I think could be a 
useful addition. (Although Python's internal workings make many 
impractical.)

http://pastebin.com/JrVTher6

This is not an attempt to compare the complete languages as they are for 
different purposes (mine is more low-level, simpler, smaller and 
designed to make it easier to create an efficient byte-code interpreter 
for it).

-- 
Bartc




From framstag at rus.uni-stuttgart.de  Thu Nov 26 07:54:58 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Thu, 26 Nov 2015 12:54:58 +0000 (UTC)
Subject: fexit: file transfer of ANY size
Message-ID: <n36vf2$86s$1@news2.informatik.uni-stuttgart.de>

In the last weeks I have asked here some beginners questions and got great
response. I was able to solve all my problems.

Now, my first real Python program is ready: fexit, a F*EX client.

And what is F*EX?
==> Frams' Fast File EXchange, a service for transfering files of ANY size
from any user A to any user B in the internet.
For details see: http://fex.rus.uni-stuttgart.de/

I am now looking for beta testers. If you are interested, send me a mail.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From marko at pacujo.net  Thu Nov 26 07:56:58 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 14:56:58 +0200
Subject: What does a list comprehension do
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
Message-ID: <87k2p4ex5x.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> Personnaly I would prefer:
>
>>>> q = [(lambda i: lambda x: i * x)(i) for i in range(4)]
>>>> q[0](1), q[3](1)
> (0, 3)
>
> And this is where I ask whether it would be worth the effort to change
> the behaviour of python.

Don't go there.

Consider:

    q = []
    n = 0
    x = "hello"

    for i in range(4):
        def stepper():
            global n
            n += 1
            return i * x
        q.append(stepper)

    print(n)
    print(q[1]())
    print(n)
    x = "there"
    print(q[3]())
    print(n)

which prints:

    0
    hellohellohello
    1
    theretherethere
    2

after your change, you'd get:

    0
    hello
    0
    hellohellohello
    0

> It also seems that people who try this for the first time are
> surprised with what they get and seem to expect there list
> comprehension to act as if they had written the second version.

I might trip over that one, too. Still, nothing should be changed.


Marko


From rosuav at gmail.com  Thu Nov 26 08:15:10 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 27 Nov 2015 00:15:10 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n36v80$1nt$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
Message-ID: <CAPTjJmr81apSbw1=YxqAP0BSRHgHuC=fsQr5EL2hOVvWOOrVQA@mail.gmail.com>

On Thu, Nov 26, 2015 at 11:53 PM, BartC <bc at freeuk.com> wrote:
> FWIW here is that list of features that are different between Python and my
> language, or that work a different way, or that I think could be a useful
> addition. (Although Python's internal workings make many impractical.)
>
> http://pastebin.com/JrVTher6
>
> This is not an attempt to compare the complete languages as they are for
> different purposes (mine is more low-level, simpler, smaller and designed to
> make it easier to create an efficient byte-code interpreter for it).

"I think Python now has hex, octal and binary literals. X allows any
base from 2 to 16: 2x10101 is binary, while 4x101 is quaternary (ie.
20)."

Do you mean that 4x101 means 1*(4*4) + 0*(4) + 1? If so, it would be
17, not 20. Is this a typo in the document, or am I misunderstanding
your syntax?

#14 and #15: Are you assuming that a character is a byte and that
diacritical-free English is the only language in the world? Case
insensitivity is a *pain* when you try to be language-agnostic; for
instance, the case-folding rules of English state that U+0069 LATIN
SMALL LETTER I and U+0049 LATIN CAPITAL LETTER I are identical, but
Turkish would upper-case the first to U+0130 LATIN CAPITAL LETTER I
WITH DOT ABOVE and lower-case the second to U+0131 LATIN SMALL LETTER
DOTLESS I. German has U+00DF LATIN SMALL LETTER SHARP S (also called
eszett), which traditionally upper-cases to "SS", which lower-cases to
"ss".

ChrisA


From gordon at panix.com  Thu Nov 26 08:25:41 2015
From: gordon at panix.com (John Gordon)
Date: Thu, 26 Nov 2015 13:25:41 +0000 (UTC)
Subject: if else python
References: <mailman.51.1448431821.20593.python-list@python.org>
Message-ID: <n3718l$7an$1@reader1.panix.com>

In <mailman.51.1448431821.20593.python-list at python.org> Scott Montreuil <scott at zml.ca> writes:

> I have an if statement which seems to run both commands and I cannot
> figure out why.

I'm not sure what you mean by "both commands".  Do you mean that the
'if' and 'else' branches both execute?

Your if/else branches are in a loop, so perhaps you're seeing the 'if'
branch on one loop iteration, anf the 'else' branch on the next iteration?

I see that your if and else branches both contain a screen.addstr()
call.  Are you seeing both of these outputs?

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"



From clalancette at gmail.com  Thu Nov 26 08:33:46 2015
From: clalancette at gmail.com (Chris Lalancette)
Date: Thu, 26 Nov 2015 08:33:46 -0500
Subject: Looking for ideas to improve library API
In-Reply-To: <5656FCC5.9000308@mrabarnett.plus.com>
References: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
 <5656FCC5.9000308@mrabarnett.plus.com>
Message-ID: <CABMb9Gt_oeajB+G2A4Lw=Lp6tfgcj=Yf5kCunGcGu25oFYPFVA@mail.gmail.com>

On Thu, Nov 26, 2015 at 7:36 AM, MRAB <python at mrabarnett.plus.com> wrote:
> Why pass a file descriptor? Why not a filename?

The reason for a file descriptor is so that I can also add other
file-like objects, such as StringIO.  My unit tests, for instance,
rely heavily on this.  That being said, it is not *strictly* required
(my unit tests could be modified to write to temporary files), but I
thought it was a nice feature.

Chris


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 08:33:59 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 14:33:59 +0100
Subject: What does a list comprehension do
In-Reply-To: <87k2p4ex5x.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
Message-ID: <56570A47.4050304@rece.vub.ac.be>

Op 26-11-15 om 13:56 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
>
>> Personnaly I would prefer:
>>
>>>>> q = [(lambda i: lambda x: i * x)(i) for i in range(4)]
>>>>> q[0](1), q[3](1)
>> (0, 3)
>>
>> And this is where I ask whether it would be worth the effort to change
>> the behaviour of python.
> Don't go there.
>
> Consider:
>
>     q = []
>     n = 0
>     x = "hello"
>
>     for i in range(4):
>         def stepper():
>             global n
>             n += 1
>             return i * x
>         q.append(stepper)
>
>     print(n)
>     print(q[1]())
>     print(n)
>     x = "there"
>     print(q[3]())
>     print(n)
>
> which prints:
>
>     0
>     hellohellohello
>     1
>     theretherethere
>     2
>
> after your change, you'd get:
>
>     0
>     hello
>     0
>     hellohellohello
>     0

I don't understand. What I propose would be a minor change in
how list comprehension works. I don't see how your example
can be turned into a list comprehension. I can of course
put the stepper function out of the for loop and then
convert the for loop into a list comprehension.

The results in that case is that my proposed change wouldn't
effect the results in python2 and that the code wouldn't run
in python3.

So could you clarify what list comprehension you are talking
about, that you think would cause trouble, should my proposal
be adopted.
-- 
Antoon.



From clalancette at gmail.com  Thu Nov 26 08:35:20 2015
From: clalancette at gmail.com (Chris Lalancette)
Date: Thu, 26 Nov 2015 08:35:20 -0500
Subject: Looking for ideas to improve library API
In-Reply-To: <CABicbJJkNCTW6PAWw_P5mQmHAwysJaG49N8C+zLV9vKQkWB8_Q@mail.gmail.com>
References: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
 <CABicbJJkNCTW6PAWw_P5mQmHAwysJaG49N8C+zLV9vKQkWB8_Q@mail.gmail.com>
Message-ID: <CABMb9GtR_WVngUUmNAVP83vXJbUZK40REfUBeBpCn3XL2YFaPw@mail.gmail.com>

On Thu, Nov 26, 2015 at 7:46 AM, Devin Jeanpierre
<jeanpierreda at gmail.com> wrote:
> Why not take ownership of the file object, instead of requiring users
> to manage lifetimes?

Yeah, I've kind of been coming to this conclusion.  So my question
then becomes: how do I "take ownership" of it?  I already keep a
reference to it, but how would I signal to the API user that they
should no longer use that file object (other than documentation)?

Thanks,
Chris


From marko at pacujo.net  Thu Nov 26 08:56:41 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 15:56:41 +0200
Subject: What does a list comprehension do
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
 <mailman.138.1448544914.20593.python-list@python.org>
Message-ID: <87fuzseuee.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

> I don't understand. What I propose would be a minor change in
> how list comprehension works. I don't see how your example
> can be turned into a list comprehension.

The list comprehension is only a special case of the interaction between
closures and variables. If you dabble with list comprehensions and
lambdas, you'll need to make consistent changes in closure semantics.

That would lead to the trouble I mentioned. Closures need to have
dynamic access to the variables they refer to.

This whole issue is a consequence of Python's assignment semantics. If
Python didn't allow altering the values of variables, we wouldn't be
having this discussion.

BTW, all(!?) other languages from Java to Scheme share closure semantics
with Python so you would really be making a mess by changing Python.


Marko


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 09:26:47 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 15:26:47 +0100
Subject: What does a list comprehension do
In-Reply-To: <87fuzseuee.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
 <mailman.138.1448544914.20593.python-list@python.org>
 <87fuzseuee.fsf@elektro.pacujo.net>
Message-ID: <565716A7.4080707@rece.vub.ac.be>

Op 26-11-15 om 14:56 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
>
>> I don't understand. What I propose would be a minor change in
>> how list comprehension works. I don't see how your example
>> can be turned into a list comprehension.
> The list comprehension is only a special case of the interaction between
> closures and variables. If you dabble with list comprehensions and
> lambdas, you'll need to make consistent changes in closure semantics.

It would only dabble with the list comprehension not with the lambda.
The effect of the change would only be that a list comprehension like

    [ <expression> for <var> in <iter> ]

would implicitly be rewritten as follows:

    [ (lambda <var>: <expression>)(<var>) for <var> in <iter>]

There would no change on how lambdas work or functions or closures.

> BTW, all(!?) other languages from Java to Scheme share closure semantics
> with Python so you would really be making a mess by changing Python.

Not this proposal, which wouldn't touch closure semantics.

-- 
Antoon.



From bc at freeuk.com  Thu Nov 26 09:40:15 2015
From: bc at freeuk.com (BartC)
Date: Thu, 26 Nov 2015 14:40:15 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.140.1448547231.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
 <mailman.140.1448547231.20593.python-list@python.org>
Message-ID: <n375g8$pvv$1@dont-email.me>

On 26/11/2015 13:15, Chris Angelico wrote:
> On Thu, Nov 26, 2015 at 11:53 PM, BartC <bc at freeuk.com> wrote:
>> FWIW here is that list of features that are different between Python and my
>> language, or that work a different way, or that I think could be a useful
>> addition. (Although Python's internal workings make many impractical.)
>>
>> http://pastebin.com/JrVTher6
>>
>> This is not an attempt to compare the complete languages as they are for
>> different purposes (mine is more low-level, simpler, smaller and designed to
>> make it easier to create an efficient byte-code interpreter for it).
>
> "I think Python now has hex, octal and binary literals. X allows any
> base from 2 to 16: 2x10101 is binary, while 4x101 is quaternary (ie.
> 20)."
>
> Do you mean that 4x101 means 1*(4*4) + 0*(4) + 1? If so, it would be
> 17, not 20. Is this a typo in the document, or am I misunderstanding
> your syntax?

Just a mistake. The example had been 4x100 which is 16, but I changed it 
to 4x101 for a bit less confusion, which as you say is 17 not 20 which 
is 4x110.

(Although not used much, I have used quaternary here for example:

   4x3032_3233_2323

The digits represent the number of extra days more than 28 in each 
month, from Jan to Dec.)


-- 
Bartc


From denismfmcmahon at gmail.com  Thu Nov 26 09:49:39 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Thu, 26 Nov 2015 14:49:39 -0000 (UTC)
Subject: Screen scraper to get all 'a title' elements
References: <23ed6f4b-0ef2-4c9e-ade6-e597e7e03ca2@googlegroups.com>
Message-ID: <n37663$h02$1@dont-email.me>

On Wed, 25 Nov 2015 12:42:00 -0800, ryguy7272 wrote:

> Hello experts.  I'm looking at this url:
> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
> 
> I'm trying to figure out how to list all 'a title' elements.

a is the element tag, title is an attribute of the htmlanchorelement.

combining bs4 with python structures allows you to find all the specified 
attributes of an element type, for example to find the class attributes 
of all the paragraphs with a class attribute:

stuff = [p.attrs['class'] for p in soup.find_all('p') if 'class' in 
p.attrs]

Then you can do this

for thing in stuff:
    print thing

(Python 2.7)

This may be adaptable to your requirement.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From lac at openend.se  Thu Nov 26 10:20:50 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 26 Nov 2015 16:20:50 +0100
Subject: Python on windows 10 
In-Reply-To: <CY1PR13MB0809508315283B56278491A7AA050@CY1PR13MB0809.namprd13.prod.outlook.com>
References: <CY1PR13MB0809508315283B56278491A7AA050@CY1PR13MB0809.namprd13.prod.outlook.com>
Message-ID: <201511261520.tAQFKodc009450@fido.openend.se>

In a message of Wed, 25 Nov 2015 20:34:01 +0000, francis funari writes:
>I have tried installing Python 3 on windows 10 it install OK but I do not get Idle. When I type Idle in the interpreter nothing happen can you send me a link to latest release of Python 3 with Idle that will run on windows 10 64 bit
>                                                                                                              Thankyou Francis Funari
>
>Sent from Mail<http://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>-- 
>https://mail.python.org/mailman/listinfo/python-list

Sorry to hear you are having problems.

Can you please go to a command window and type

python -m idlelib  

This should fail.  However, it should fail with a meaningful traceback
which indicates where the problem is.  Copy and paste that traceback 
into mail and post that here so we have proceed.

If 'python' isn't the command you need to use to get python3.5 
perhaps py -3.5 -m idlelib will work.  But the idea is we want to
catch idle failing, so we can figure out what is going on.

Laura Creighton


From tjreedy at udel.edu  Thu Nov 26 10:24:37 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Thu, 26 Nov 2015 10:24:37 -0500
Subject: Python on windows 10
In-Reply-To: <CY1PR13MB0809508315283B56278491A7AA050@CY1PR13MB0809.namprd13.prod.outlook.com>
References: <CY1PR13MB0809508315283B56278491A7AA050@CY1PR13MB0809.namprd13.prod.outlook.com>
Message-ID: <n37886$nls$1@ger.gmane.org>

On 11/25/2015 3:34 PM, francis funari wrote:
> I have tried installing Python 3 on windows 10 it install OK but I do
> not get Idle. When I type Idle in the interpreter nothing happen

Starting programs by typing their names into the interactive interpreter 
does not work.

Use Start Menu | All Apps | Python 3.5 | IDLE (...).  You can make this 
a Start Menu 'favorite' or create a Desktop icon.  Typing 'idle' in the 
Command Prompt console may also work.  Typing 'python -m idlelib' should 
work.  After I start IDLE once I pin it to the taskbar since I use it 
constantly.

-- 
Terry Jan Reedy



From marko at pacujo.net  Thu Nov 26 10:36:33 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 17:36:33 +0200
Subject: What does a list comprehension do
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
 <mailman.138.1448544914.20593.python-list@python.org>
 <87fuzseuee.fsf@elektro.pacujo.net>
 <mailman.141.1448548095.20593.python-list@python.org>
Message-ID: <87k2p43h8e.fsf@elektro.pacujo.net>

Antoon Pardon <antoon.pardon at rece.vub.ac.be>:

>     [ <expression> for <var> in <iter> ]
>
> would implicitly be rewritten as follows:
>
>     [ (lambda <var>: <expression>)(<var>) for <var> in <iter>]

Funny enough, that's how "list comprehensions" are created in Scheme:

   (map (lambda (i)
          (lambda (x) (* i x)))
        '(0 1 2 3))))

> There would no change on how lambdas work or functions or closures.

First of all, it's weird to spend any effort in trying to alter a very
special case. I don't recall having to generate a list of such
functions. In fact, I barely ever use lambda in Python; explicit def
statements are much more pleasing to the eye and are not restricted to
simple expressions.

Secondly, you'd lose the nice symmetry between for statements and
comprehensions/generators. For example:

   ( lambda x: i * x for i in range(4) )

corresponds to:

    for i in range(4):
        yield lambda x: i * x

Would you embed an extra lambda there, too?

How about:

    i = 0
    while i < 4:
        yield lambda x: i * x
        i += 1

or:

    for i in range(4):
        def f(x):
            return i * x
        yield f


Marko


From gandalf at shopzeus.com  Thu Nov 26 10:56:21 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Thu, 26 Nov 2015 16:56:21 +0100
Subject: ANN: tornadostreamform
Message-ID: <56572BA5.1080705@shopzeus.com>


Pure python module that let?s you upload *huge* files to a tornado web
server.

This project provides the
|tornadostreamform.multipart_streamer.MultiPartStreamer| class that
incrementally parses incoming multipart/form-data, splits it into form
fields, and streams the fields into file like objects (temp file, opened
pipe, network socket etc.) With this class, it is possible to POST/PUT
large files to a tornado server, without loading anything big into
memory. Can be used as an alternative to the ngnx large file upload
extension (especially when you want to stream files into process pipes).


The PyPi package contains the classes only. The bitbucket repository
contains some examples.

PyPi: https://pypi.python.org/pypi/tornadostreamform
Documentation: https://pypi.python.org/pypi/tornadostreamform
Repository: https://bitbucket.org/nagylzs/tornadostreamform

Cheers,

   Laszlo


From gandalf at shopzeus.com  Thu Nov 26 10:56:59 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Thu, 26 Nov 2015 16:56:59 +0100
Subject: ANN: tornadostreamform
In-Reply-To: <56572BA5.1080705@shopzeus.com>
References: <56572BA5.1080705@shopzeus.com>
Message-ID: <56572BCB.4030605@shopzeus.com>


> PyPi: https://pypi.python.org/pypi/tornadostreamform
> Documentation: https://pypi.python.org/pypi/tornadostreamform
Wrong paste. Here is the good one:
https://pythonhosted.org/tornadostreamform/



From harvest at is.invalid  Thu Nov 26 11:11:57 2015
From: harvest at is.invalid (Jussi Piitulainen)
Date: Thu, 26 Nov 2015 18:11:57 +0200
Subject: What does a list comprehension do
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
 <mailman.138.1448544914.20593.python-list@python.org>
 <87fuzseuee.fsf@elektro.pacujo.net>
 <mailman.141.1448548095.20593.python-list@python.org>
Message-ID: <lf5vb8oyc36.fsf@ling.helsinki.fi>

Antoon Pardon writes:
> Op 26-11-15 om 14:56 schreef Marko Rauhamaa:
>> Antoon Pardon wrote:
>>
>>> I don't understand. What I propose would be a minor change in how
>>> list comprehension works. I don't see how your example can be turned
>>> into a list comprehension.
>>
>> The list comprehension is only a special case of the interaction
>> between closures and variables. If you dabble with list
>> comprehensions and lambdas, you'll need to make consistent changes in
>> closure semantics.
>
> It would only dabble with the list comprehension not with the lambda.
> The effect of the change would only be that a list comprehension like
>
>     [ <expression> for <var> in <iter> ]
>
> would implicitly be rewritten as follows:
>
>     [ (lambda <var>: <expression>)(<var>) for <var> in <iter>]
>
> There would no change on how lambdas work or functions or closures.
>
>> BTW, all(!?) other languages from Java to Scheme share closure semantics
>> with Python so you would really be making a mess by changing Python.
>
> Not this proposal, which wouldn't touch closure semantics.

It needs to take into account the possibility of more than one variable,
but that's a minor adjustment. I like it. It's simple enough.

The following code exercises different values from nested comprehension
loops, together with a shared global whose value actually changes before
each call to one of the listed thunks.

m = "good morning to you"

thoughts = [ (lambda n, u :
                  ((lambda : (u//2)*m),
                   (lambda : n)))
             (n, u)
             for n in range(10)
             if n % 2            # odd?
             for u in range(10)
             if u % 2 - 1        # less odd?
             if n < u  ]

for t, g in zip(thoughts, ((["hello"], ["eiku"], ["hej"]) +
                           tuple(20 * "."))):
    m = g
    message, number = t
    print(number(), *message())

# Prints:
1 hello
1 eiku eiku
1 hej hej hej
1 . . . .
3 . .
3 . . .
3 . . . .
5 . . .
5 . . . .
7 . . . .


From python at mrabarnett.plus.com  Thu Nov 26 11:14:21 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 26 Nov 2015 16:14:21 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n375g8$pvv$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
 <mailman.140.1448547231.20593.python-list@python.org>
 <n375g8$pvv$1@dont-email.me>
Message-ID: <56572FDD.8000301@mrabarnett.plus.com>

On 2015-11-26 14:40, BartC wrote:
> On 26/11/2015 13:15, Chris Angelico wrote:
>> On Thu, Nov 26, 2015 at 11:53 PM, BartC <bc at freeuk.com> wrote:
>>> FWIW here is that list of features that are different between Python and my
>>> language, or that work a different way, or that I think could be a useful
>>> addition. (Although Python's internal workings make many impractical.)
>>>
>>> http://pastebin.com/JrVTher6
>>>
>>> This is not an attempt to compare the complete languages as they are for
>>> different purposes (mine is more low-level, simpler, smaller and designed to
>>> make it easier to create an efficient byte-code interpreter for it).
>>
>> "I think Python now has hex, octal and binary literals. X allows any
>> base from 2 to 16: 2x10101 is binary, while 4x101 is quaternary (ie.
>> 20)."
>>
>> Do you mean that 4x101 means 1*(4*4) + 0*(4) + 1? If so, it would be
>> 17, not 20. Is this a typo in the document, or am I misunderstanding
>> your syntax?
>
> Just a mistake. The example had been 4x100 which is 16, but I changed it
> to 4x101 for a bit less confusion, which as you say is 17 not 20 which
> is 4x110.
>
> (Although not used much, I have used quaternary here for example:
>
>     4x3032_3233_2323
>
> The digits represent the number of extra days more than 28 in each
> month, from Jan to Dec.)
>
Smalltalk uses "r" (for "radix") rather than "x", and can handle any 
base from 2 to 36.



From python at mrabarnett.plus.com  Thu Nov 26 11:16:57 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Thu, 26 Nov 2015 16:16:57 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n36v80$1nt$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
Message-ID: <56573079.5000401@mrabarnett.plus.com>

On 2015-11-26 12:53, BartC wrote:
> On 26/11/2015 01:52, Ned Batchelder wrote:
>> On Wednesday, November 25, 2015 at 8:23:36 PM UTC-5, BartC wrote:
>>> On 26/11/2015 00:31, Steven D'Aprano wrote:
>
>>>> It really, truly isn't. Your viewpoint is clouded by too much immersion in
>>>> crippled languages. *Old and obsolete versions* of crippled languages.
>>>> Dynamic creation of functions goes back to the 1950s.
>
>>> It's funny then that the vast majority of top-level function definitions
>>> I see in Python (and import and class statements too) are decidedly static.
>
>> I almost started to explain about how yes, Python is often written in
>> conservative static ways. I was going to mention that a little dynamic
>> nature goes a long way, and is never far from the surface in even the
>> simplest Python programs.
>>
>> But I won't, because I'm not sure you're really interested.  There's a
>> pattern here of people trying to explain Python to you, and eventually,
>> after many words, getting to some kind of shared understanding, only
>> for you to shrug it all off as a fad, or pocket-lining, or needless
>> complexity.
>
> I'm sorry if I've been misunderstood.
>
> I simply stated that Python's approach was novel. Steven D'Aprano then
> responded by belittling my view, and effectively trashing every language
> I've ever used.
>
[snip]
Well, it's not /that/ new.

Both Forth and PostScript define functions by execution.



From jorge.conrado at cptec.inpe.br  Thu Nov 26 12:15:43 2015
From: jorge.conrado at cptec.inpe.br (jorge.conrado at cptec.inpe.br)
Date: Thu, 26 Nov 2015 15:15:43 -0200
Subject: read 4D binary data
Message-ID: <4d15f12abb4c4781168ce05d3b450f63@cptec.inpe.br>

Hi,


I'm startig in Python and I have a 4D binary data. The dimension of my 
data is:

67 ----> longitude points
41 ----> latitude points
10 ----> pressure levels points
33 ----> time points


How can I read this data and what can I do to get a 2D array 
(longitude,latitude) for a specific pressure  and time dimension.


Conrado


From breamoreboy at yahoo.co.uk  Thu Nov 26 12:43:34 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 26 Nov 2015 17:43:34 +0000
Subject: read 4D binary data
In-Reply-To: <4d15f12abb4c4781168ce05d3b450f63@cptec.inpe.br>
References: <4d15f12abb4c4781168ce05d3b450f63@cptec.inpe.br>
Message-ID: <n37gca$u5b$1@ger.gmane.org>

On 26/11/2015 17:15, jorge.conrado at cptec.inpe.br wrote:
> Hi,
>
>
> I'm startig in Python and I have a 4D binary data. The dimension of my
> data is:
>
> 67 ----> longitude points
> 41 ----> latitude points
> 10 ----> pressure levels points
> 33 ----> time points
>
>
> How can I read this data and what can I do to get a 2D array
> (longitude,latitude) for a specific pressure  and time dimension.
>
>
> Conrado

To open a file to access the contents 
https://docs.python.org/3/library/functions.html#open

If the data is in CSV format see https://docs.python.org/3/library/csv.html

For your data structure lists 
https://docs.python.org/3/library/stdtypes.html#lists and dicts 
https://docs.python.org/3/library/stdtypes.html#mapping-types-dict are 
always the first port of call.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From denismfmcmahon at gmail.com  Thu Nov 26 12:52:16 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Thu, 26 Nov 2015 17:52:16 -0000 (UTC)
Subject: read 4D binary data
References: <mailman.148.1448558147.20593.python-list@python.org>
Message-ID: <n37gsf$h02$5@dont-email.me>

On Thu, 26 Nov 2015 15:15:43 -0200, jorge.conrado wrote:

> I'm startig in Python and I have a 4D binary data. The dimension of my
> data is:
> 
> 67 ----> longitude points 41 ----> latitude points 10 ----> pressure
> levels points 33 ----> time points
> 
> How can I read this data and what can I do to get a 2D array
> (longitude,latitude) for a specific pressure  and time dimension.

First of all, define the data structure you want to create.

I would have thought that for any given time, you would want a 2d array 
containing the pressure at each point (given by lat and lon) at that time.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From lac at openend.se  Thu Nov 26 13:00:35 2015
From: lac at openend.se (Laura Creighton)
Date: Thu, 26 Nov 2015 19:00:35 +0100
Subject: read 4D binary data
In-Reply-To: <4d15f12abb4c4781168ce05d3b450f63@cptec.inpe.br>
References: <4d15f12abb4c4781168ce05d3b450f63@cptec.inpe.br>
Message-ID: <201511261800.tAQI0ZIO011744@fido.openend.se>

In a message of Thu, 26 Nov 2015 15:15:43 -0200, jorge.conrado at cptec.inpe.br wr
ites:
>Hi,
>
>
>I'm startig in Python and I have a 4D binary data. The dimension of my 
>data is:
>
>67 ----> longitude points
>41 ----> latitude points
>10 ----> pressure levels points
>33 ----> time points
>
>
>How can I read this data and what can I do to get a 2D array 
>(longitude,latitude) for a specific pressure  and time dimension.
>
>
>Conrado

If your binary data is all of the same type -- these are all floats,
or all ints -- you can use the python array module to read it.
https://docs.python.org/3/library/array.html

If they are heterogenous then you cannot use array, but can use struct
https://docs.python.org/3.5/library/struct.html

If I were you, I would want to get my data into pandas, which is
the best tool for data analysis
http://pandas.pydata.org/

And I would do this pretty much exactly as 
Albert Jan outlines in this stackoverflow question.
http://stackoverflow.com/questions/16573089/reading-binary-data-into-pandas
though, as I said, if your data is homogeneous you can use the array
module instead of using the struct one.  But struct will work on
homogenous data as well -- it is just slower.  You may not care.

Note that Albert Jan's answer is the one on the bottom, i.e. not the
one that got the checkmark from the original poster.

Laura


From antoon.pardon at rece.vub.ac.be  Thu Nov 26 14:18:14 2015
From: antoon.pardon at rece.vub.ac.be (Antoon Pardon)
Date: Thu, 26 Nov 2015 20:18:14 +0100
Subject: What does a list comprehension do
In-Reply-To: <87k2p43h8e.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <877fldnm9z.fsf@handshake.de>
 <mailman.73.1448459485.20593.python-list@python.org>
 <pan.2015.11.26.11.13.43.440000@nowhere.invalid>
 <mailman.132.1448538769.20593.python-list@python.org>
 <87k2p4ex5x.fsf@elektro.pacujo.net>
 <mailman.138.1448544914.20593.python-list@python.org>
 <87fuzseuee.fsf@elektro.pacujo.net>
 <mailman.141.1448548095.20593.python-list@python.org>
 <87k2p43h8e.fsf@elektro.pacujo.net>
Message-ID: <56575AF6.1050202@rece.vub.ac.be>

Op 26-11-15 om 16:36 schreef Marko Rauhamaa:
> Antoon Pardon <antoon.pardon at rece.vub.ac.be>:
> 
>>     [ <expression> for <var> in <iter> ]
>>
>> would implicitly be rewritten as follows:
>>
>>     [ (lambda <var>: <expression>)(<var>) for <var> in <iter>]
> 
> Funny enough, that's how "list comprehensions" are created in Scheme:
> 
>    (map (lambda (i)
>           (lambda (x) (* i x)))
>         '(0 1 2 3))))
> 
>> There would no change on how lambdas work or functions or closures.
> 
> First of all, it's weird to spend any effort in trying to alter a very
> special case.

<shrug> Maybe it is small enough an effort but I wont loose any sleep over it
should the dev team have other priorities.

> I don't recall having to generate a list of such
> functions. In fact, I barely ever use lambda in Python; explicit def
> statements are much more pleasing to the eye and are not restricted to
> simple expressions.
> 
> Secondly, you'd lose the nice symmetry between for statements and
> comprehensions/generators. For example:
> 
>    ( lambda x: i * x for i in range(4) )
> 
> corresponds to:
> 
>     for i in range(4):
>         yield lambda x: i * x
> 
> Would you embed an extra lambda there, too?

No, not because that would be so troublesome in semantics
but because it would be annoying in python. Because in that
case you would embed a function (call) or introduce an
intermediate scope. Which would mean that if you want
to rebind a variable within the suite of the for loop
that is also used in other parts of the function/modules
you would have to declare that variable nonlocal/global at the
start of the suite. So it would be annoying plus that
it would be difficult to explain to people new to the
language.

Such an embedding would only be practical in a language where
you have to declare your variables.

-- 
Antoon.


From ben+python at benfinney.id.au  Thu Nov 26 15:00:56 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 27 Nov 2015 07:00:56 +1100
Subject: Object identity has no necessary connection to memory location
References: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <mailman.129.1448537076.20593.python-list@python.org>
 <1esd5bdujvog21u4qu6llhna5c3d573873@4ax.com>
Message-ID: <85fuzsa5tz.fsf@benfinney.id.au>

Dave Farrance <df at see.replyto.invalid> writes:

> >> >Dave Farrance <df at see.replyto.invalid>:
> >> >
> >> >> (Conversely, I see that unlike CPython, all PyPy's numbers have
> >> >> unchanging ids, even after exiting PyPy and restarting, so it seems
> >> >> that PyPy's numerical ids are "faked".)
>
> Hence
>
> https://en.wikipedia.org/wiki/Scare_quotes

I saw the scare quotes. They still communicate your position that object
identity ?should? be reliably connected to the object's memory location.

Either you don't hold that position, in which case your original
statement was as ambiguous as this most recent one you wrote; or you do
hold that position, and my response stands.

-- 
 \       ?When I was little, my grandfather used to make me stand in a |
  `\   closet for five minutes without moving. He said it was elevator |
_o__)                                        practice.? ?Steven Wright |
Ben Finney



From hb.heber at gmail.com  Thu Nov 26 15:16:54 2015
From: hb.heber at gmail.com (Heber Futuri)
Date: Thu, 26 Nov 2015 15:16:54 -0500
Subject: it's posible? raw audio encoder to vorbis
Message-ID: <CA+3gEyseSJLUxoiZ3tOfcgM1GX0VBnKTMVR6EwcXbTYafJqqQg@mail.gmail.com>

Receipt from websocket server audio raw and I want to encode ogg

help! :(

from websocket_server import WebsocketServer
# Called when a client sends a messagedef data_received(client, server, datos):
    #HERE encoder "datos" to ogg and save data


PORT=9001
server = WebsocketServer(PORT)
server.set_fn_message_received(data_received)
server.run_forever()


From vincentypedro at gmail.com  Thu Nov 26 15:34:36 2015
From: vincentypedro at gmail.com (vincentypedro at gmail.com)
Date: Thu, 26 Nov 2015 12:34:36 -0800 (PST)
Subject: reading from a txt file
Message-ID: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>

Hey, I'm wondering how to read individual strings in a text file.  I can read a text file by lines with .readlines() , 
but I need to read specifically by strings, not including spaces.  Thanks in advance


From denismfmcmahon at gmail.com  Thu Nov 26 15:50:26 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Thu, 26 Nov 2015 20:50:26 -0000 (UTC)
Subject: reading from a txt file
References: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
Message-ID: <n37rah$h02$8@dont-email.me>

On Thu, 26 Nov 2015 12:34:36 -0800, vincentypedro wrote:

> Hey, I'm wondering how to read individual strings in a text file.  I can
> read a text file by lines with .readlines() ,
> but I need to read specifically by strings, not including spaces. 
> Thanks in advance

How do you define a string? Is it just a line with the spaces removed?

>>> "".join("    this is a test    string my     friends    ".split(" "))
'thisisateststringmyfriends'

-- 
Denis McMahon, denismfmcmahon at gmail.com


From gherron at digipen.edu  Thu Nov 26 16:01:55 2015
From: gherron at digipen.edu (Gary Herron)
Date: Thu, 26 Nov 2015 13:01:55 -0800
Subject: reading from a txt file
In-Reply-To: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
References: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
Message-ID: <56577343.4080901@digipen.edu>

On 11/26/2015 12:34 PM, vincentypedro at gmail.com wrote:
> Hey, I'm wondering how to read individual strings in a text file.  I can read a text file by lines with .readlines() ,
> but I need to read specifically by strings, not including spaces.  Thanks in advance

Read the lines with readlines(), as you say, then split each line into 
whatever pieces you want with split (or with any of the many other 
string methods).

A minimal example (without readlines):
 >>> lines = ['a b c', 'aa bb cc']
 >>> for line in lines:
...   words = line.split()
...   print(words)
...
['a', 'b', 'c']
['aa', 'bb', 'cc']


-- 
Dr. Gary Herron
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418



From jsf80238 at gmail.com  Thu Nov 26 16:04:34 2015
From: jsf80238 at gmail.com (Jason Friedman)
Date: Thu, 26 Nov 2015 14:04:34 -0700
Subject: reading from a txt file
In-Reply-To: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
References: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
Message-ID: <CANy1k1gxdwwy61p1fENdHSnDY30JRGeVY8adirr+_xhYk26TqQ@mail.gmail.com>

>
> Hey, I'm wondering how to read individual strings in a text file.  I can
> read a text file by lines with .readlines() ,
> but I need to read specifically by strings, not including spaces.  Thanks
> in advance
>

How about:

for a_string in open("/path/to/file").read().split():
    print(a_string)


From greg.ewing at canterbury.ac.nz  Thu Nov 26 16:20:57 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Fri, 27 Nov 2015 10:20:57 +1300
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <87a8q1f9ni.fsf@elektro.pacujo.net>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>	<mailman.484.1447964295.16136.python-list@python.org>	<87d1v5emhl.fsf@elektro.pacujo.net>	<564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>	<56556DF8.1080407@rece.vub.ac.be>	<mailman.56.1448440353.20593.python-list@python.org>	<n349qb$qj4$1@dont-email.me>
 <878u5mns8z.fsf@elektro.pacujo.net>	<n34dfe$8n5$1@dont-email.me>
 <874mganq2q.fsf@elektro.pacujo.net>	<n34gor$kq8$1@dont-email.me>	<56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>	<87oaeh2qy0.fsf@elektro.pacujo.net>	<mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
Message-ID: <dbpbdrFce6nU1@mid.individual.net>

Marko Rauhamaa wrote:
> What I'm saying is that Python does not prevent mutable keys but tries
> to do that with lists and tuples.
> 
> I think Python should stop trying.

Do you volunteer to answer all the posts from beginners
complaining that "the dict type is broken" because they
used a list as a key and then mutated it?

-- 
Greg


From Cecil at decebal.nl  Thu Nov 26 16:33:17 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Thu, 26 Nov 2015 22:33:17 +0100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl>
 <5656c2e0$0$11120$c3e8da3@news.astraweb.com>
Message-ID: <87d1uwe99e.fsf@Equus.decebal.nl>

On Thursday 26 Nov 2015 09:29 CET, Steven D'Aprano wrote:

> On Thursday 26 November 2015 18:00, Cecil Westerhof wrote:
>
>> On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:
>>
>>> In a message of Wed, 25 Nov 2015 22:52:23 +0100, Cecil Westerhof
>>> writes:
>>>>
>>>> My system python was all-ready damaged: that is why I wanted to
>>>> build myself.
>>>
>>> Your Suse system probably wants to use python for something. If
>>> your system python is damaged, you badly need to fix that, using
>>> the system package managers tools, before Suse does some sort of
>>> update on you, using the broken python, which damages more of your
>>> system.
>>
>> I tried that. But it installs only things in /usr/lib and
>> /usr/lib64, nothing in /usr/bin, but at the same time it is adamant
>> that it installed python. I wanted a quick fix, but it looks like
>> that is not going to work. :'-( I'll have to find a way to get
>> things fixed.
>>
>
> On the assumption that you are more interested in fixing your broken
> system than learning how to compile Python, what happens if you use
> the Suse package manager to re-install Python?
>
> e.g. zypper python

It installs things in /usr/lib and /usr/lib64, but nothing in
/usr/bin. So it installs libraries, but not programs.


By the way: I am of-course most interested to fix my system, but I
would not mind to have python compiled also, so I (can) work with the
latest stable version. ;-)

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From marko at pacujo.net  Thu Nov 26 16:36:13 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Thu, 26 Nov 2015 23:36:13 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net> <dbpbdrFce6nU1@mid.individual.net>
Message-ID: <87egfc30ky.fsf@elektro.pacujo.net>

Gregory Ewing <greg.ewing at canterbury.ac.nz>:

> Marko Rauhamaa wrote:
>> What I'm saying is that Python does not prevent mutable keys but
>> tries to do that with lists and tuples.
>>
>> I think Python should stop trying.
>
> Do you volunteer to answer all the posts from beginners complaining
> that "the dict type is broken" because they used a list as a key and
> then mutated it?

What happened to consenting adults?

Even Java (of all languages) allows lists to be keys and simply notes:

   Note: great care must be exercised if mutable objects are used as map
   keys.

   <URL: http://docs.oracle.com/javase/7/docs/api/java/util/Map.html>


Marko


From Cecil at decebal.nl  Thu Nov 26 16:39:01 2015
From: Cecil at decebal.nl (Cecil Westerhof)
Date: Thu, 26 Nov 2015 22:39:01 +0100
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl>
 <pdpd5b9nn14apgog6pie58lhr2ivfo9i57@4ax.com>
Message-ID: <878u5ke8zu.fsf@Equus.decebal.nl>

On Thursday 26 Nov 2015 12:07 CET, Dave Farrance wrote:

> Cecil Westerhof <Cecil at decebal.nl> wrote:
>
>> On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:
>>>
>>> Your Suse system probably wants to use python for something. If
>>> your system python is damaged, you badly need to fix that, using
>>> the system package managers tools, before Suse does some sort of
>>> update on you, using the broken python, which damages more of your
>>> system.
>>
>> I tried that. But it installs only things in /usr/lib and
>> /usr/lib64, nothing in /usr/bin, but at the same time it is adamant
>> that it installed python. I wanted a quick fix, but it looks like
>> that is not going to work. :'-( I'll have to find a way to get
>> things fixed.
>
> A complete reinstall of Suse (after saving your home directory and
> work) might be quickest if you're in the dark about what's broken.
>
> But you might be able to fix it. If you can figure out which
> packages contain the damaged files, then do forced reinstalls of
> those. I've not used Suse, but a quick Google tells me that the
> syntax is:
>
> zypper in -f <package-name>
>
> So you'll want to try package names like "python" and "python2.7".

Sadly that also only installs only libraries and no applications.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof


From breamoreboy at yahoo.co.uk  Thu Nov 26 16:44:41 2015
From: breamoreboy at yahoo.co.uk (Mark Lawrence)
Date: Thu, 26 Nov 2015 21:44:41 +0000
Subject: Object identity has no necessary connection to memory location
In-Reply-To: <85fuzsa5tz.fsf@benfinney.id.au>
References: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <mailman.129.1448537076.20593.python-list@python.org>
 <1esd5bdujvog21u4qu6llhna5c3d573873@4ax.com> <85fuzsa5tz.fsf@benfinney.id.au>
Message-ID: <n37ugd$rdk$1@ger.gmane.org>

On 26/11/2015 20:00, Ben Finney wrote:
> Dave Farrance <df at see.replyto.invalid> writes:
>
>>>>> Dave Farrance <df at see.replyto.invalid>:
>>>>>
>>>>>> (Conversely, I see that unlike CPython, all PyPy's numbers have
>>>>>> unchanging ids, even after exiting PyPy and restarting, so it seems
>>>>>> that PyPy's numerical ids are "faked".)
>>
>> Hence
>>
>> https://en.wikipedia.org/wiki/Scare_quotes
>
> I saw the scare quotes. They still communicate your position that object
> identity ?should? be reliably connected to the object's memory location.
>
> Either you don't hold that position, in which case your original
> statement was as ambiguous as this most recent one you wrote; or you do
> hold that position, and my response stands.
>

It still fascinates me that after roughly 15 years using Python I've 
never considered using object identity, let alone actually done so. 
What, if anything, have I missed out on?

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence



From greg.ewing at canterbury.ac.nz  Thu Nov 26 16:48:46 2015
From: greg.ewing at canterbury.ac.nz (Gregory Ewing)
Date: Fri, 27 Nov 2015 10:48:46 +1300
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n36v80$1nt$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
Message-ID: <dbpd20FcqvnU1@mid.individual.net>

BartC wrote:
> I simply stated that Python's approach was novel. Steven D'Aprano then 
> responded by belittling my view, and effectively trashing every language 
> I've ever used.

He pointed out that many other dynamic languages construct
functions on the fly the same way that Python does, going
all the way back to the earliest Lisp implementations. If
you think that Python invented that idea, then either you
haven't studied any of those languages, or you didn't
realise that's what they were doing. If your view was
"belittled" in any way, it's only because you said something
that is objectively wrong.

> But as it happens I do think features like first class functions are 
> overrated (and probably the software underpinning the hardware we're all 
> using is written in the very languages he despises). I don't think a 
> language is worthless without such a feature.

I think Steven went off on a bit of a tangent there.
First-classness of functions doesn't really have anything
to do with whether they're constructed statically or
dynamically. C lets you pass pointers to functions around,
for example, but I don't think anyone would describe C
as executing function definitions at run time.

While a language isn't worthless without first-class
functions, such a language tends to feel rather limited
if you're used to having them. Think of any API that
involves passing in callback functions, and what you
would have to do if you didn't have that ability.

Anyhow, the whole issue of static vs. dynamic function
creation is itself tangential to what started all this.
I think Laura Creighton has it right: Python provides
exactly *one* way to delay evaluation of code: put it
in the body of a function. That's a very simple rule,
and I think maintaining that simplicity is a good
thing.

-- 
Greg


From bc at freeuk.com  Thu Nov 26 17:27:52 2015
From: bc at freeuk.com (BartC)
Date: Thu, 26 Nov 2015 22:27:52 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <mailman.140.1448547231.20593.python-list@python.org>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
 <mailman.140.1448547231.20593.python-list@python.org>
Message-ID: <n380t1$b69$1@dont-email.me>

On 26/11/2015 13:15, Chris Angelico wrote:
> On Thu, Nov 26, 2015 at 11:53 PM, BartC <bc at freeuk.com> wrote:

>> http://pastebin.com/JrVTher6

> #14 and #15: Are you assuming that a character is a byte and that
> diacritical-free English is the only language in the world?

I don't think that need be the assumption. Any UTF8 string that fits 
within 8 bytes could also be represented by an integer value.

> Case
> insensitivity is a *pain* when you try to be language-agnostic; for
> instance, the case-folding rules of English state that U+0069 LATIN
> SMALL LETTER I and U+0049 LATIN CAPITAL LETTER I are identical, but
> Turkish would upper-case the first to U+0130 LATIN CAPITAL LETTER I
> WITH DOT ABOVE and lower-case the second to U+0131 LATIN SMALL LETTER
> DOTLESS I. German has U+00DF LATIN SMALL LETTER SHARP S (also called
> eszett), which traditionally upper-cases to "SS", which lower-cases to
> "ss".

I use Windows which is also case insensitive with regard to filenames 
and such. How does it solve those problems? How about web-site names, 
email addresses and Google searches?

Within a program source code (where you have mainly technical users), 
you can just impose some restrictions on keywords and identifiers 
otherwise there are plenty of problems even without case switching, if 
you want to allow Unicode here.


-- 
Bartc


From rosuav at gmail.com  Thu Nov 26 18:07:34 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 27 Nov 2015 10:07:34 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <n380t1$b69$1@dont-email.me>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
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Message-ID: <CAPTjJmr=6y1v66s5AEcBT7w9e7TvXPg8B-XnGU-sbi=WXgt49g@mail.gmail.com>

On Fri, Nov 27, 2015 at 9:27 AM, BartC <bc at freeuk.com> wrote:
> On 26/11/2015 13:15, Chris Angelico wrote:
>>
>> On Thu, Nov 26, 2015 at 11:53 PM, BartC <bc at freeuk.com> wrote:
>
>
>>> http://pastebin.com/JrVTher6
>
>
>> #14 and #15: Are you assuming that a character is a byte and that
>> diacritical-free English is the only language in the world?
>
>
> I don't think that need be the assumption. Any UTF8 string that fits within
> 8 bytes could also be represented by an integer value.

Okay, so you're making UTF-8 your visible string representation.
That's better than assuming character==byte, but it still has the case
insensitivity problem.

>> Case
>> insensitivity is a *pain* when you try to be language-agnostic; for
>> instance, the case-folding rules of English state that U+0069 LATIN
>> SMALL LETTER I and U+0049 LATIN CAPITAL LETTER I are identical, but
>> Turkish would upper-case the first to U+0130 LATIN CAPITAL LETTER I
>> WITH DOT ABOVE and lower-case the second to U+0131 LATIN SMALL LETTER
>> DOTLESS I. German has U+00DF LATIN SMALL LETTER SHARP S (also called
>> eszett), which traditionally upper-cases to "SS", which lower-cases to
>> "ss".
>
>
> I use Windows which is also case insensitive with regard to filenames and
> such. How does it solve those problems? How about web-site names, email
> addresses and Google searches?

Windows: I'm not sure, and frankly, I don't trust it. A quick test
showed a couple of failures:

C:\Users\Rosuav\Desktop>dir /b TE*
te?ting
C:\Users\Rosuav\Desktop>dir /b TESST*
File Not Found

C:\Users\Rosuav\Desktop>dir /b Par?ld?YOR*
Par?ld?yor Parts & Pieces
C:\Users\Rosuav\Desktop>dir /b PARILDIYOR*
File Not Found

It might be case insensitive only for ASCII.

(Note: This test was done on Windows 7, because that's the VM I had
handy. Things might be different on newer Windowses, but I can't
check.

Web site names: Presumably you mean DNS. It started out as an
ASCII-only protocol, and grew a number of gross hacks to support
"internationalized domain names". I'm not sure where the case
insensitivity is applied; but it doesn't matter too much, because
conflicts can be resolved at registration. Also, you'll generally see
IDNs in country-specific TLDs, so there'll be only one language (or a
small family of languages) used, reducing the likelihood of
collisions.

Google searches are (deliberately) a LOT more sloppy than just case
sensitivity. You can search for something without diacriticals and get
back results with diacriticals; you can transpose letters, omit
letters, have extra letters, and it'll generally figure out what you
want. This is absolutely awesome for a search engine, but equally
horrifying for name lookups in a program.

None of these is something I'd recommend following.

> Within a program source code (where you have mainly technical users), you
> can just impose some restrictions on keywords and identifiers otherwise
> there are plenty of problems even without case switching, if you want to
> allow Unicode here.

I would strongly support ASCII-only *language keywords*. You don't
have many of them (compared to the number of identifiers in a
program), and everyone has to type them. But for identifiers, Python 3
defines character validity based on Unicode categories, and performs
NFKC normalization on all names. That's pretty straight-forward. No
case sensitivity hassles, no messy non-transitive equalities, it's
easy.

ChrisA


From random832 at fastmail.com  Thu Nov 26 19:15:21 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 26 Nov 2015 19:15:21 -0500
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <m2si3s70x2.fsf@fastmail.com>

Chris Angelico <rosuav at gmail.com> writes:
> Windows: I'm not sure, and frankly, I don't trust it. A quick test
> showed a couple of failures:
> 
> It might be case insensitive only for ASCII.

Windows uses a simple WCHAR->WCHAR (lower->upper) mapping for case
comparison. it doesn't handle those cases, but it does handle all BMP
characters that have a simple case equivalent within the BMP as of the
unicode version that Microsoft supported when the disk was formatted.

It's unfair to pick the two worst examples that you know offhand and
declare that this means "only for ASCII". Pick any latin-1 (etc)
diacritic, any letter of the greek and cyrillic alphabet, and it'll
handle them just fine.

OSX fails the same cases, incidentally.



From rosuav at gmail.com  Thu Nov 26 19:48:14 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 27 Nov 2015 11:48:14 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <m2si3s70x2.fsf@fastmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <CAPTjJmoo_ZP2fatWLYsOHx9gjWZxzeu1_TibQvNhcruxMwrARQ@mail.gmail.com>

On Fri, Nov 27, 2015 at 11:15 AM, Random832 <random832 at fastmail.com> wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>> Windows: I'm not sure, and frankly, I don't trust it. A quick test
>> showed a couple of failures:
>>
>> It might be case insensitive only for ASCII.
>
> Windows uses a simple WCHAR->WCHAR (lower->upper) mapping for case
> comparison. it doesn't handle those cases, but it does handle all BMP
> characters that have a simple case equivalent within the BMP as of the
> unicode version that Microsoft supported when the disk was formatted.
>
> It's unfair to pick the two worst examples that you know offhand and
> declare that this means "only for ASCII". Pick any latin-1 (etc)
> diacritic, any letter of the greek and cyrillic alphabet, and it'll
> handle them just fine.
>

I picked a couple of test cases, found them to not do the case
insensitivity special cases, and concluded that I don't understand
Windows' file system case folding (with the possibility that it's an
ASCII-only case fold).

Anyway, it's still not something I would recommend; if you want true
case folding, you need to go the whole way - and it still has
problems.

ChrisA


From steve at pearwood.info  Thu Nov 26 20:09:53 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:09:53 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
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 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
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Message-ID: <5657ad63$0$1600$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 12:23 pm, BartC wrote:

> On 26/11/2015 00:31, Steven D'Aprano wrote:

>> In 2015, it's hard to think of any non-obsolete, non-toy language which
>> doesn't treat functions as first-class values, including creating them on
>> the fly. Fortran and C perhaps.
> 
> It's funny then that the vast majority of top-level function definitions
> I see in Python (and import and class statements too) are decidedly
> static.

I can't be held responsible for what code you see.

It is probably true that many, maybe even a majority, of top-level
functions, and methods, are static. So what? That's not the point. The
point is that *more than that is possible*, so when you need the power, you
have it.

Any time you see a function decorator:

@decorate
def function(arg): ...


you're probably seeing a dynamically-generated function. The typical
decorator idiom looks like this:

def decorate(function):
    @functools.wraps(function)
    def inner(arg):
        do stuff
        call the original function
        return the result
    return inner


Lo and behold, the simple @decorate idiom usually hides a function created
on the fly. (That would be the inner function, which is called a closure.)

Any time you see a function factory, chances are good that it involves
dynamic generation of function objects.

Any time you see lambda, you are definitely seeing the dynamic generation of
function objects. If you do any sort of programming involving callbacks
(for example, some GUI toolkits, like Tkinter, make extensive use of
callbacks) you probably will use lambda a lot.

The equivalent to lambda, code blocks, is even more powerful in Ruby, and
Ruby programmers use code blocks *a lot*. So much so that I know at least
one Ruby programmer who considers Python almost unusably primitive and
crippled because it lacks code blocks.

You really should read Paul Graham's essay, "Beating the Averages", and
understand the Blub Paradox. (It's not really a paradox.) It might open
your eyes.

[quote]
As long as our hypothetical Blub programmer is looking down the power
continuum, he knows he's looking down. Languages less powerful than Blub
are obviously less powerful, because they're missing some feature he's used
to. But when our hypothetical Blub programmer looks in the other direction,
up the power continuum, he doesn't realize he's looking up. What he sees
are merely weird languages. He probably considers them about equivalent in
power to Blub, but with all this other hairy stuff thrown in as well. Blub
is good enough for him, because he thinks in Blub.
[end quote]

http://www.paulgraham.com/avg.html


We're all Blub programmers. But some of us are aware that we're Blub
programmers, and when we see "weird languages" with "hairy stuff", we don't
immediately dismiss the possibility that maybe that stuff is powerful and
useful, just because we've never found a use for it.



> The names are declared, but the names are rarely bound to anything else.
> Functions are just called the same boring way they are in C.
> 
> /They might as well be static definitions/.

Sure. And that's probably true for, oh, I don't know, I'll be generous, and
say that 95% of Python functions in use are of a straight-forward
pseudo-static form, using no dynamic features.

But it's the other 5% -- one in twenty -- that *shine*. They're the ones
that do things that you can't do in Pascal or C except with the greatest of
difficulty.

Back when I was an undergrad at uni, I did a course on computational
mathematics. At the time, Pascal was the language of choice at my uni, and
when it came to solving ODEs (Ordinary Differential Equations) we used a
package of Pascal programs to do so.

Because Pascal doesn't have first-class functions, you couldn't pass a
function as an argument to another function. So the ODE solvers used a
hard-coded function as the equation to be solved. So if you wanted to solve
a particular equation, you had to *edit the source code of the program*,
modifying that hard-coded function to match your equation, then re-compile,
and then run the code. You couldn't just type in the equation you wanted to
solve and run the code.

Of course Pascal is Turing Complete, and the solver could have been written
to work that way. It just would have been much, much, much harder.
Something that in a language like Python you can do almost without
thinking:

function(another_function, x, y, z)

would have required hundreds, perhaps thousands or tens of thousands of
lines to do in standard Pascal. You would have had to build up all this
infrastructure for dealing with functions that Python gives you for free.

There's a lot to like about Pascal, but gosh it sure is lacking in power. C
at least has function pointers, which is a step up from Pascal, but still
pretty weak and feeble. If functions are first class values in Python,
Ruby, Lisp and others, they're second class values in C and third class in
Pascal.




-- 
Steven



From python at mrabarnett.plus.com  Thu Nov 26 20:15:00 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Fri, 27 Nov 2015 01:15:00 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <m2si3s70x2.fsf@fastmail.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <n36v80$1nt$1@dont-email.me>
 <mailman.140.1448547231.20593.python-list@python.org>
 <n380t1$b69$1@dont-email.me>
 <CAPTjJmr=6y1v66s5AEcBT7w9e7TvXPg8B-XnGU-sbi=WXgt49g@mail.gmail.com>
 <m2si3s70x2.fsf@fastmail.com>
Message-ID: <5657AE94.4010002@mrabarnett.plus.com>

On 2015-11-27 00:15, Random832 wrote:
> Chris Angelico <rosuav at gmail.com> writes:
>> Windows: I'm not sure, and frankly, I don't trust it. A quick test
>> showed a couple of failures:
>>
>> It might be case insensitive only for ASCII.
>
> Windows uses a simple WCHAR->WCHAR (lower->upper) mapping for case
> comparison. it doesn't handle those cases, but it does handle all BMP
> characters that have a simple case equivalent within the BMP as of the
> unicode version that Microsoft supported when the disk was formatted.
>
Interesting, on Windows 10, "dir" on the command line treats
"TE?TING.txt" and "te?ting.txt" as equivalent, whereas a file dialog
treats "TE?TING.txt", "te?ting.txt" and "TESSTING.txt" as equivalent.

They don't treat "Par?ld?YOR.txt" and "PARILDIYOR.txt" as equivalent,
which doesn't surprise me.

> It's unfair to pick the two worst examples that you know offhand and
> declare that this means "only for ASCII". Pick any latin-1 (etc)
> diacritic, any letter of the greek and cyrillic alphabet, and it'll
> handle them just fine.
>
> OSX fails the same cases, incidentally.
>



From steve at pearwood.info  Thu Nov 26 20:23:11 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:23:11 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
Message-ID: <5657b081$0$1586$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 07:27 pm, Marko Rauhamaa wrote:

> What I'm saying is that Python does not prevent mutable keys but tries
> to do that with lists and tuples.
> 
> I think Python should stop trying.
> 
> I have wanted to use lists as keys, and there should be no reason to
> allow mutable tuples. It should be enough to say that the behavior of a
> dictionary is undefined if a key should mutate on the fly.

Well, when you design your own language, you can make all the bad design
decisions you like :-)

Seriously, if you think *this* thread about mutable function defaults has
been long, can you imagine the bug reports and arguments if this was
possible in Python?


L = [1, 2]
d = {L: "found it"}

# much later, after L has been modified...

d[ [1, 2] ]
=> raises KeyError



But even worse:


a = [1, 2]
b = [1, 3]
d = {a: "spam", b: "ham"}
a[1] += 1

What will d[ [1, 3] ] return?


-- 
Steven



From vincentypedro at gmail.com  Thu Nov 26 20:24:38 2015
From: vincentypedro at gmail.com (Pedro Vincenty)
Date: Thu, 26 Nov 2015 17:24:38 -0800 (PST)
Subject: reading from a txt file
In-Reply-To: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
References: <175ab5d2-d8e3-44e7-a71f-88b3153daf89@googlegroups.com>
Message-ID: <1e567393-3750-43f2-8e7c-6e92f687ce9f@googlegroups.com>

All were really helpful thanks a lot.  Now I'm interested in identifying a particular index after being able to print out each word.  Printing each word to the console I have : 

['METEOSAT-7']
['1', '24932U', '97049B', '15319.57839525', '.00000058', '00000-0', '00000+0', '0', '9994']
['2', '24932', '9.9015', '42.7484', '0001500', '224.8381', '52.7416', '1.00266716', '66645']

It seems awkward because I was expecting to have brackets only outside of all the words.  I would like to identify one of these words.  Thanks again!


From steve at pearwood.info  Thu Nov 26 20:28:29 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:28:29 +1100
Subject: Question about output different with command dis.dis(code)
References: <f0dc1c2c-6fda-4bd8-a71b-29db358afe14@googlegroups.com>
Message-ID: <5657b1bf$0$1601$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 08:02 pm, fl wrote:

> Hi,
> 
> I see the following from a previous post:
> 
> 
> Python 1.5.2 (#1, Aug 27 2012, 09:09:18)  [GCC 4.1.2 20080704 (Red Hat
> 4.1.2-52)] on linux2
> Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>>> import dis
>>>> code = compile("(1, 2, 3)", "", "eval")
>>>> dis.dis(code)
>           0 SET_LINENO          0
>           3 LOAD_CONST          0 (1)
>           6 LOAD_CONST          1 (2)
>           9 LOAD_CONST          2 (3)
>          12 BUILD_TUPLE         3
>          15 RETURN_VALUE


This output is from Python 1.5, which is about 20 years old or so, and long
obsolete.


> When I run the above three line code, I get the following:
> 
> dis.dis(code)
>   1           0 LOAD_CONST               3 ((1, 2, 3))
>               3 RETURN_VALUE


This output is (probably) from Python 2.7, which is much more recent. The
byte-code compiler is much smarter now than in old versions of Python.


By the way, this is a really good question! I especially like the fact that
you tried running the code for yourself first.




-- 
Steven



From steve at pearwood.info  Thu Nov 26 20:34:02 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:34:02 +1100
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
Message-ID: <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 09:34 pm, Dave Farrance wrote:


> (Conversely, I see that unlike CPython, all PyPy's numbers have
> unchanging ids, even after exiting PyPy and restarting, so it seems that
> PyPy's numerical ids are "faked".)
> 
> [PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>>> id(1+2j)
> 679900119843984469027190799480815353863L
> 
> [PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>>> id(1+2j)
> 679900119843984469027190799480815353863L


I'm pretty sure that they are faked.

I remember seeing a question on the pypy-dev mailing list asking whether it
was important that object IDs remained stable. They had a problem where the
JIT compiler would take a Python list, convert it to a low-level array of
machine-sized ints for fast processing, and then recreate the list. This
all happened in the background without the user knowing, and the PyPy devs
needed to know if it was important that the object ID of the new list
matched the old list.

The language guarantees that the id of an object won't change for the
lifespan of the object, and consequently PyPy has to fake them.


-- 
Steven



From ben+python at benfinney.id.au  Thu Nov 26 20:40:06 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 27 Nov 2015 12:40:06 +1100
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <8537vs9q4p.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> On Thu, 26 Nov 2015 09:34 pm, Dave Farrance wrote:
>
>
> > (Conversely, I see that unlike CPython, all PyPy's numbers have
> > unchanging ids, even after exiting PyPy and restarting, so it seems
> > that PyPy's numerical ids are "faked".)
>
> I'm pretty sure that they are faked.

It's still not been expressed what ?fake? refers to here. Or, rather,
what ?real? thing was being expected, and how these don't qualify.

The object IDs are real IDs, they identify the object, they're not
pretending to be anything other than object IDs, they are perfectly
compliant with the language definition and all the documentation.

What is fake? What ?real? thing was expected, and *why* was that
expected?

-- 
 \     ?Do unto others twenty-five percent better than you expect them |
  `\      to do unto you. (The twenty-five percent is [to correct] for |
_o__)                            error.)? ?Linus Pauling's Golden Rule |
Ben Finney



From steve at pearwood.info  Thu Nov 26 20:43:05 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:43:05 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <56556DF8.1080407@rece.vub.ac.be>
 <mailman.56.1448440353.20593.python-list@python.org>
 <n349qb$qj4$1@dont-email.me> <878u5mns8z.fsf@elektro.pacujo.net>
 <n34dfe$8n5$1@dont-email.me> <874mganq2q.fsf@elektro.pacujo.net>
 <n34gor$kq8$1@dont-email.me>
 <56565822$0$1617$c3e8da3$5496439d@news.astraweb.com>
 <87oaeh2qy0.fsf@elektro.pacujo.net>
 <mailman.117.1448525450.20593.python-list@python.org>
 <87a8q1f9ni.fsf@elektro.pacujo.net>
 <mailman.120.1448526890.20593.python-list@python.org>
 <87610pf2uq.fsf@elektro.pacujo.net>
 <mailman.127.1448535849.20593.python-list@python.org>
 <87wpt5dmxg.fsf@elektro.pacujo.net>
Message-ID: <5657b52c$0$1617$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 10:23 pm, Marko Rauhamaa wrote:

> Chris Angelico <rosuav at gmail.com>:
> 
>> On Thu, Nov 26, 2015 at 9:54 PM, Marko Rauhamaa <marko at pacujo.net> wrote:
>>>
>>>    >>> hash([])
>>>    Traceback (most recent call last):
>>>      File "<stdin>", line 1, in <module>
>>>    TypeError: unhashable type: 'list'
>>>
>>> Annoying.
>>
>> Yes, it's really annoying that you get an immediate exception instead
>> of unpredictably getting bizarre failures that depend on the exact
>> bucket sizes and dict size and so on. It's such a pain to get told
>> exactly where the problem is.
> 
> The problem is that lists don't have __hash__ and __eq__ defined.


I'm pretty sure that lists have __eq__ defined :-P



>> Python tends to assume that programmers are intelligent people who are
>> prepared to fix their mistakes.
> 
> It's not letting me in the case of list.


Less whining, more programming:

class MyList(list):
    def __hash__(self):
        return 1


There you go, problem solved. New problems are your responsibility:


py> a = MyList([1, 2])
py> d = {a: "spam"}
py> d[MyList([1, 2])]  # Looks good so far.
'spam'
py> a.append(3)
py> d[MyList([1, 2])]  # Where did my key go?
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: [1, 2]


py> b = MyList([1, 3])
py> d[b] = "eggs"
py> d[MyList([1, 3])]  # So far so good.
'eggs'
py> b[1] -= 1
py> b.append(3)
py> d[b]  # What?
'spam'


All I can say is, this would be an absolutely awesome feature for Python to
have, if you were being paid by the hour for debugging.



-- 
Steven



From steve at pearwood.info  Thu Nov 26 20:46:01 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 12:46:01 +1100
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
Message-ID: <5657b5db$0$1617$c3e8da3$5496439d@news.astraweb.com>

On Thu, 26 Nov 2015 12:52 pm, Ned Batchelder wrote:

> For someone who claims to be interested in language design, you're
> remarkably dismissive of pretty much the entire industry.  I don't think
> it's worth the effort to try to change your mind.

In fairness to BartC, I don't think that's malicious or trolling. I think it
is as pure an example of what Paul Graham calls the Blub Paradox as I've
ever seen.



-- 
Steven



From bc at freeuk.com  Thu Nov 26 21:01:28 2015
From: bc at freeuk.com (BartC)
Date: Fri, 27 Nov 2015 02:01:28 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <5657b5db$0$1617$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <b70213fa-2b4a-475b-a444-eaaf43c2a69e@googlegroups.com>
 <5657b5db$0$1617$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n38ddi$jrc$1@dont-email.me>

On 27/11/2015 01:46, Steven D'Aprano wrote:
> On Thu, 26 Nov 2015 12:52 pm, Ned Batchelder wrote:
>
>> For someone who claims to be interested in language design, you're
>> remarkably dismissive of pretty much the entire industry.  I don't think
>> it's worth the effort to try to change your mind.
>
> In fairness to BartC, I don't think that's malicious or trolling. I think it
> is as pure an example of what Paul Graham calls the Blub Paradox as I've
> ever seen.

"Well, PaulGraham has a very (very) low opinion of OO, mostly because he 
does a lot of stuff that most people haven't been able to do, and he 
says he almost never "resorts" to it. However, more recent posts on LL1 
suggest PaulGraham is coming around. He's starting to be less derogatory 
to OO (and seems to have done a 180 on continuations). No one, not even 
PaulGraham himself, ever said that PaulGraham was immune to the 
BlubParadox. ;) "

http://c2.com/cgi/wiki?BlubParadox

-- 
bartc


From steve at pearwood.info  Thu Nov 26 21:17:53 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 13:17:53 +1100
Subject: Object identity has no necessary connection to memory location
References: <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <871tbdf2o0.fsf@elektro.pacujo.net>
 <70qd5b9lbtjlsotn7d21gor4rd67o79ou7@4ax.com>
 <mailman.129.1448537076.20593.python-list@python.org>
 <1esd5bdujvog21u4qu6llhna5c3d573873@4ax.com>
 <mailman.152.1448568068.20593.python-list@python.org>
Message-ID: <5657bd52$0$1610$c3e8da3$5496439d@news.astraweb.com>

On Fri, 27 Nov 2015 07:00 am, Ben Finney wrote:

> Dave Farrance <df at see.replyto.invalid> writes:
> 
>> >> >Dave Farrance <df at see.replyto.invalid>:
>> >> >
>> >> >> (Conversely, I see that unlike CPython, all PyPy's numbers have
>> >> >> unchanging ids, even after exiting PyPy and restarting, so it seems
>> >> >> that PyPy's numerical ids are "faked".)
>>
>> Hence
>>
>> https://en.wikipedia.org/wiki/Scare_quotes
> 
> I saw the scare quotes. They still communicate your position that object
> identity ?should? be reliably connected to the object's memory location.
> 
> Either you don't hold that position, in which case your original
> statement was as ambiguous as this most recent one you wrote; or you do
> hold that position, and my response stands.


Ben is right that object IDs are not promised to have any connection to
object memory location. In Jython and IronPython, for example, objects
appear to be given sequential IDs based on when you first ask for their ID.
This is in IronPython:

>>> a = []
>>> b = []
>>> id(b)
43
>>> id(a)
44


Jython is similar, except the IDs are 1 and 2 rather than 43 and 44. (All
these results are subject to change, of course.)

But (I think) that Dave is right that PyPy fakes IDs, in the sense that
objects can be destroyed and recreated behind the scenes in PyPy without
your knowledge.

As I understand it, what appears to be happening is that PyPy can take
Python objects, convert them to low-level machine values (destroying the
Python object in the process), perform processing on the machine values,
and recreate the Python object before you know it is gone. The consequence
of that is that what we see as a single Python object with a fixed lifespan
may in fact be multiple objects with much shorter lifespans.

I'm rather partial to science fiction analogies, so here is one: when
Captain Kirk uses the transporter to beam down to the Planet Of Hot Space
Babes Wearing Hats With A Moral Lesson For Us All, we see Kirk on the
Enterprise disappear and then re-appear on the planet a moment later. As
far as we are concerned, and as far as Kirk is concerned, he has existed
the whole time he was in transport. If he had an itchy nose just as he
left, it's still itchy when he arrives, and if he is transported
mid-thought, he finishes the thought when he arrives. There's no perception
of discontinuity.

But as Scotty well knows, in fact Kirk's entire body is ripped into atoms by
the transporter beam, utterly destroying Kirk in the process, then
transported via some oh-so-clever quantum-magical^W quantum-mechanical
trick, to be reassembled at the other end. Although Kirk doesn't feel like
he ceased to exist and then was re-created, in fact that's exactly what
happened. One second after arriving on the planet, Kirk's body is now
precisely one second old. It may not even be made of the same atoms that
his former body was made of.

In PyPy, an object's lifetime is not necessarily the same as the lifetime of
the actual block of memory used for that object. Not only might objects be
relocated in space (as they can be in IronPython and Jython) but in time as
well.



-- 
Steven



From steve at pearwood.info  Thu Nov 26 21:44:05 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 13:44:05 +1100
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
Message-ID: <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>

On Fri, 27 Nov 2015 12:40 pm, Ben Finney wrote:

> Steven D'Aprano <steve at pearwood.info> writes:
> 
>> On Thu, 26 Nov 2015 09:34 pm, Dave Farrance wrote:
>>
>>
>> > (Conversely, I see that unlike CPython, all PyPy's numbers have
>> > unchanging ids, even after exiting PyPy and restarting, so it seems
>> > that PyPy's numerical ids are "faked".)
>>
>> I'm pretty sure that they are faked.
> 
> It's still not been expressed what ?fake? refers to here. Or, rather,
> what ?real? thing was being expected, and how these don't qualify.

They are faked in the sense that in this implementation, the object lifespan
that you think of as the Python programmer has little if any connection to
the actual lifespan of the chunk of memory representing that object.

Suppose you have a Python object which in turn contains three other objects:

L = [10001, 10002, 10003]

Take the id of that list:

myid = id(L)

You do some long-running processing of that list, and then compare the id at
the end:

assert myid == id(L)

This is guaranteed to pass by the language definition.

We can say that at *every instant* from the creation of the list to the
moment it is garbage collected, if you took a snap-shot of the process'
memory, and manually scanned through it, you could be able to identify four
object structs, corresponding to the list and the three ints. They might
move around and be found in different memory locations, (as in IronPython
and Jython), but they will be there.

But not with PyPy. Not only might the objects have moved location, but in
some snapshots you won't find them at all. The JIT compiler may convert the
high-level Python objects (a list, and three ints) to (let's say) a
low-level array containing three C shorts, perform processing on that, and
then recreate the Python objects only when finished.

Looked at from the perspective of the implementation, the actual lifespan of
the objects (in the sense of the struct in memory that represents that
object) may be much less than what we see from the perspective of the
high-level Python code.

Of course in Python, the object continues to exist the whole time, as far as
we can tell -- there is no test we can do from Python code that can
distinguish the state of the object, just as there is no test we can do
from Python to tell whether an object has moved memory location or not. But
from outside of Python -- say, a debugger that hooks into the particular
implementation, or by taking a dump of the memory and looking at it in a
hex editor -- we can see the high-level objects come and go and move
around.

The PyPy implementation has to take special actions to preserve the ID
across object recreations. That is what I mean by "faked".



-- 
Steven



From python at mrabarnett.plus.com  Thu Nov 26 21:56:12 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Fri, 27 Nov 2015 02:56:12 +0000
Subject: What is a function parameter =[] for?
In-Reply-To: <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <5657C64C.1020807@mrabarnett.plus.com>

On 2015-11-27 02:44, Steven D'Aprano wrote:
> On Fri, 27 Nov 2015 12:40 pm, Ben Finney wrote:
>
>> Steven D'Aprano <steve at pearwood.info> writes:
>>
>>> On Thu, 26 Nov 2015 09:34 pm, Dave Farrance wrote:
>>>
>>>
>>> > (Conversely, I see that unlike CPython, all PyPy's numbers have
>>> > unchanging ids, even after exiting PyPy and restarting, so it seems
>>> > that PyPy's numerical ids are "faked".)
>>>
>>> I'm pretty sure that they are faked.
>>
>> It's still not been expressed what ?fake? refers to here. Or, rather,
>> what ?real? thing was being expected, and how these don't qualify.
>
> They are faked in the sense that in this implementation, the object lifespan
> that you think of as the Python programmer has little if any connection to
> the actual lifespan of the chunk of memory representing that object.
>
> Suppose you have a Python object which in turn contains three other objects:
>
> L = [10001, 10002, 10003]
>
> Take the id of that list:
>
> myid = id(L)
>
> You do some long-running processing of that list, and then compare the id at
> the end:
>
> assert myid == id(L)
>
> This is guaranteed to pass by the language definition.
>
> We can say that at *every instant* from the creation of the list to the
> moment it is garbage collected, if you took a snap-shot of the process'
> memory, and manually scanned through it, you could be able to identify four
> object structs, corresponding to the list and the three ints. They might
> move around and be found in different memory locations, (as in IronPython
> and Jython), but they will be there.
>
> But not with PyPy. Not only might the objects have moved location, but in
> some snapshots you won't find them at all. The JIT compiler may convert the
> high-level Python objects (a list, and three ints) to (let's say) a
> low-level array containing three C shorts, perform processing on that, and
> then recreate the Python objects only when finished.
>
> Looked at from the perspective of the implementation, the actual lifespan of
> the objects (in the sense of the struct in memory that represents that
> object) may be much less than what we see from the perspective of the
> high-level Python code.
>
> Of course in Python, the object continues to exist the whole time, as far as
> we can tell -- there is no test we can do from Python code that can
> distinguish the state of the object, just as there is no test we can do
> from Python to tell whether an object has moved memory location or not. But
> from outside of Python -- say, a debugger that hooks into the particular
> implementation, or by taking a dump of the memory and looking at it in a
> hex editor -- we can see the high-level objects come and go and move
> around.
>
> The PyPy implementation has to take special actions to preserve the ID
> across object recreations. That is what I mean by "faked".
>
You could argue that it _does_ continue to exist, it just changes its 
form...



From rosuav at gmail.com  Thu Nov 26 22:06:42 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 27 Nov 2015 14:06:42 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <5657C64C.1020807@mrabarnett.plus.com>
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
 <5657C64C.1020807@mrabarnett.plus.com>
Message-ID: <CAPTjJmrkn468vq9UGEowkbCVY=fNHOC7J72T1gU3=rUiSSCmiA@mail.gmail.com>

On Fri, Nov 27, 2015 at 1:56 PM, MRAB <python at mrabarnett.plus.com> wrote:
> You could argue that it _does_ continue to exist, it just changes its
> form...

PyPy: The Quantum Mechanics of Python programming. If you aren't
actually looking at something right at this instant, it might exist in
a different form... or not exist at all. But hey! By the time you get
to look at it again, it'll exist just as if it was never gone!

ChrisA


From random832 at fastmail.com  Thu Nov 26 23:33:53 2015
From: random832 at fastmail.com (Random832)
Date: Thu, 26 Nov 2015 23:33:53 -0500
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <m2lh9k6oy6.fsf@fastmail.com>

Steven D'Aprano <steve at pearwood.info> writes:

> On Thu, 26 Nov 2015 09:34 pm, Dave Farrance wrote:
>
>
>> (Conversely, I see that unlike CPython, all PyPy's numbers have
>> unchanging ids, even after exiting PyPy and restarting, so it seems that
>> PyPy's numerical ids are "faked".)
>> 
>> [PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>>>> id(1+2j)
>> 679900119843984469027190799480815353863L
>> 
>> [PyPy 2.6.1 with GCC 4.9.2] on linux2
>>>>>> id(1+2j)
>> 679900119843984469027190799480815353863L
>
>
> I'm pretty sure that they are faked.

The hex value may be instructive:

0x1ff800000000000020000000000000007L

That's 0x3ff00000000000004000000000000000 << 3 | 7.

3ff000... is the double representation of 1, 400000... is 2.

I bet that that three-bit field at the end has different values for all
the different types they are "faked" for, and one for the ones that
they're "not faked".



From ben+python at benfinney.id.au  Thu Nov 26 23:56:40 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 27 Nov 2015 15:56:40 +1100
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <85y4dk82gn.fsf@benfinney.id.au>

Steven D'Aprano <steve at pearwood.info> writes:

> On Fri, 27 Nov 2015 12:40 pm, Ben Finney wrote:
>
> > It's still not been expressed what ?fake? refers to here. Or, rather,
> > what ?real? thing was being expected, and how these don't qualify.
>
> They are faked in the sense that in this implementation, the object
> lifespan that you think of as the Python programmer has little if any
> connection to the actual lifespan of the chunk of memory representing
> that object.

Since that's nothing to do with the definition nor API of an object ID,
I think all the uses of ?faked? so far in this thread just don't apply
to PyPy's object IDs.

> The PyPy implementation has to take special actions to preserve the ID
> across object recreations. That is what I mean by "faked".

Thanks for the interesting explanation. I don't think any of this makes
PyPy's object IDs in any sense not-real-object-IDs, so I disagree with
using ?faked? to characterise them.

None of CPython, Jython, PyPy, etc. have object IDs that are anything
but real object IDs, IMO.

-- 
 \      ?[Entrenched media corporations will] maintain the status quo, |
  `\       or die trying. Either is better than actually WORKING for a |
_o__)                  living.? ?ringsnake.livejournal.com, 2007-11-12 |
Ben Finney



From zachary.ware+pylist at gmail.com  Fri Nov 27 00:48:30 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Thu, 26 Nov 2015 23:48:30 -0600
Subject: Help needed with compiling python
In-Reply-To: <878u5ke8zu.fsf@Equus.decebal.nl>
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl> <pdpd5b9nn14apgog6pie58lhr2ivfo9i57@4ax.com>
 <878u5ke8zu.fsf@Equus.decebal.nl>
Message-ID: <CAKJDb-Njb73BuLuHYHDdyGngpvKjXhd6bXx5hsXhsqd6GAPtjQ@mail.gmail.com>

On Thu, Nov 26, 2015 at 3:39 PM, Cecil Westerhof <Cecil at decebal.nl> wrote:
> On Thursday 26 Nov 2015 12:07 CET, Dave Farrance wrote:
>> zypper in -f <package-name>
>>
>> So you'll want to try package names like "python" and "python2.7".
>
> Sadly that also only installs only libraries and no applications.

Try "python-base".  (See `zypper wp /usr/bin/python`).

-- 
Zach


From kevin.p.dwyer at gmail.com  Fri Nov 27 01:46:23 2015
From: kevin.p.dwyer at gmail.com (Kev Dwyer)
Date: Fri, 27 Nov 2015 06:46:23 +0000
Subject: Help needed with compiling python
References: <877fl596c6.fsf@Equus.decebal.nl>
 <mailman.94.1448484579.20593.python-list@python.org>
 <8737vt927c.fsf@Equus.decebal.nl>
 <mailman.102.1448492328.20593.python-list@python.org>
 <87h9k9dz2t.fsf@Equus.decebal.nl>
 <5656c2e0$0$11120$c3e8da3@news.astraweb.com>
 <87d1uwe99e.fsf@Equus.decebal.nl>
Message-ID: <n38u7v$iid$1@ger.gmane.org>

Cecil Westerhof wrote:

> On Thursday 26 Nov 2015 09:29 CET, Steven D'Aprano wrote:
> 
>> On Thursday 26 November 2015 18:00, Cecil Westerhof wrote:
>>
>>> On Wednesday 25 Nov 2015 23:58 CET, Laura Creighton wrote:
>>>
>>>> In a message of Wed, 25 Nov 2015 22:52:23 +0100, Cecil Westerhof
>>>> writes:
>>>>>
>>>>> My system python was all-ready damaged: that is why I wanted to
>>>>> build myself.
>>>>
>>>> Your Suse system probably wants to use python for something. If
>>>> your system python is damaged, you badly need to fix that, using
>>>> the system package managers tools, before Suse does some sort of
>>>> update on you, using the broken python, which damages more of your
>>>> system.
>>>
>>> I tried that. But it installs only things in /usr/lib and
>>> /usr/lib64, nothing in /usr/bin, but at the same time it is adamant
>>> that it installed python. I wanted a quick fix, but it looks like
>>> that is not going to work. :'-( I'll have to find a way to get
>>> things fixed.
>>>
>>
>> On the assumption that you are more interested in fixing your broken
>> system than learning how to compile Python, what happens if you use
>> the Suse package manager to re-install Python?
>>
>> e.g. zypper python
> 
> It installs things in /usr/lib and /usr/lib64, but nothing in
> /usr/bin. So it installs libraries, but not programs.
> 
> 
> By the way: I am of-course most interested to fix my system, but I
> would not mind to have python compiled also, so I (can) work with the
> latest stable version. ;-)
> 

FWIW, I'm running OpenSuse 13.2 on a number of machines.  Pythons built
with make altinstall have the python executable placed in /usr/local/bin.

e.g.:

kev at pluto ~  which python3.5
/usr/local/bin/python3.5

kev at pluto ~  which python2.7
/usr/local/bin/python2.7


NB due to http://bugs.python.org/issue15631 I find I have to symlink 
lib-dynload to get a working python:

kev at pluto ~  ls -l /usr/local/lib/python3.5/lib-dynload
lrwxrwxrwx 1 root root 38 Sep 26 19:51 /usr/local/lib/python3.5/lib-dynload 
-> /usr/local/lib64/python3.5/lib-dynload

Having said that, I'd still recommend that you follow everyone else's advice 
and fix your system python/rebuild your OS.  Opensuse has not attempted to 
install python 2.7.9 on any of my (fully patched) machines, so something is 
wrong with your install, unless you're using Tumbleweed.

Cheers,

Kev



From dieter at handshake.de  Fri Nov 27 02:30:51 2015
From: dieter at handshake.de (dieter)
Date: Fri, 27 Nov 2015 08:30:51 +0100
Subject: Py_NewInterpreter() - Fatal Error with ceval - orphan tstate
References: <CAGQhfC5ZSZyyL7kmaQmL=ECqCU_Ruy4ytXMYpDeJR=HdKLQ05A@mail.gmail.com>
Message-ID: <87wpt3ew5w.fsf@handshake.de>

"ramjee a.g." <ramjee.ag at gmail.com> writes:

> I am using python 2.7 for extending my C++ application with python.
>
> And when two pthread of C is executing Py_NewInterpreter() it is throwing
> faltal error with ceval-orphan tstate.  There is no problem when sequential
> thread execution.

"tstate" likely stands for "thread state".

Python must somewhere store important information of the currently
running Python thread - and apparently, your use of "Py_NewInterpreter"
confuses this management.

Maybe, the "tstate" is a global variable and you cannot have multiple
interpreters at the same time. I suggest to have a look at Python's
C implementation, especially the location where the error comes from.



From jfong at ms4.hinet.net  Fri Nov 27 02:51:35 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Thu, 26 Nov 2015 23:51:35 -0800 (PST)
Subject: python response slow when running external DLL
Message-ID: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>

I am new to Python. As an exercise of it, I try to port a program which was written more than 10 years ago. This program use the Borland C++ Builder as its GUI front end and a DLL does the real work(it will takes a few seconds to complete). I saw a strange phenomenon in the following codes. The "var_status.set('Download...')" statement seems was deferred and didn't show up until the external DLL job was finished and I can only saw the result of "var_status.set('Download OK')" statement which immediately follows. I try to do the DLL function in a thread(selected by using the "test" flag in codes), but it didn't help.

Can anyone tell me what's the point I was missed?

-------------------------
def download():
    global iniFilename
    if test:  global result, busy
    ini = iniFilename
    iniFilename = "c:\\$$temp.in3"
    saveIniFile()
    iniFilename = ini
    #do the rest
    var_status.set('Download...')
    if not test:
        result = mydll.SayHello()
    else:
        busy = True
        _thread.start_new_thread(td_download, ())
        while busy:  pass
    if result:
        var_status.set("Download Fail at %s" % hex(result))
        showerror('Romter', 'Download Fail')
    else:
        var_status.set('Download OK')            
        showinfo('Romter', 'Download OK')

if test:
result = 0x5555
busy = True
def td_download():
    global busy, result
    result = mydll.SayHello()
    busy = False
--------------------------

Best Regards,
Jach


From __peter__ at web.de  Fri Nov 27 04:18:35 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 27 Nov 2015 10:18:35 +0100
Subject: python response slow when running external DLL
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
Message-ID: <n3975b$osk$1@ger.gmane.org>

jfong at ms4.hinet.net wrote:

> I am new to Python. As an exercise of it, I try to port a program which
> was written more than 10 years ago. This program use the Borland C++
> Builder as its GUI front end and a DLL does the real work(it will takes a
> few seconds to complete). I saw a strange phenomenon in the following
> codes. The "var_status.set('Download...')" statement seems was deferred
> and didn't show up until the external DLL job was finished and I can only
> saw the result of "var_status.set('Download OK')" statement which
> immediately follows. I try to do the DLL function in a thread(selected by
> using the "test" flag in codes), but it didn't help.
> 
> Can anyone tell me what's the point I was missed?

What does var_status.set() do? If it writes to stdout you may just need to 
flush().

Do you see the same behaviour when you replace mydll.SayHello() with 
something simple like time.sleep(1)?

> -------------------------
> def download():
>     global iniFilename
>     if test:  global result, busy
>     ini = iniFilename
>     iniFilename = "c:\\$$temp.in3"
>     saveIniFile()
>     iniFilename = ini
>     #do the rest
>     var_status.set('Download...')
>     if not test:
>         result = mydll.SayHello()
>     else:
>         busy = True
>         _thread.start_new_thread(td_download, ())
>         while busy:  pass
>     if result:
>         var_status.set("Download Fail at %s" % hex(result))
>         showerror('Romter', 'Download Fail')
>     else:
>         var_status.set('Download OK')
>         showinfo('Romter', 'Download OK')
> 
> if test:
> result = 0x5555
> busy = True
> def td_download():
>     global busy, result
>     result = mydll.SayHello()
>     busy = False
> --------------------------

As a general remark keep your test scripts as simple as possible. Example: 
If 

import mydll
print("Download...", end="")
mydll.SayHello()
print("OK")

showed the same behaviour it would be the ideal test script.



From rianconnery at googlemail.com  Fri Nov 27 04:43:53 2015
From: rianconnery at googlemail.com (justin bloomer)
Date: Fri, 27 Nov 2015 01:43:53 -0800 (PST)
Subject: Help with this program???
Message-ID: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>

Your program should contain a function that:
1. Seeks input from the user (via the keyboard);
2. To build a list of student exam results;
3. For each student their name (first and last), student number, and mark
out of 100 should be captured;
4. For full marks regular expressions or similar mechanisms should be used
to ensure the data appears valid.


From ben+python at benfinney.id.au  Fri Nov 27 04:57:27 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Fri, 27 Nov 2015 20:57:27 +1100
Subject: Help with this program???
References: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
Message-ID: <85poyv933s.fsf@benfinney.id.au>

justin bloomer via Python-list <python-list at python.org> writes:

> Your program should contain a function that:

This is a homework assignment, yes?

We're not going to write the code for you. If you have a program you
already wrote, we can offer feedback on *your* code.

You should also collaborate with other classmates in the course, or look
into the course material your teacher has provided.

-- 
 \     ?Why doesn't Python warn that it's not 100% perfect? Are people |
  `\         just supposed to ?know? this, magically?? ?Mitya Sirenef, |
_o__)                                     comp.lang.python, 2012-12-27 |
Ben Finney



From rosuav at gmail.com  Fri Nov 27 04:57:55 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Fri, 27 Nov 2015 20:57:55 +1100
Subject: Help with this program???
In-Reply-To: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
References: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
Message-ID: <CAPTjJmruTJK6raW36OYGYkSow3jDgQSjEbtcdwReE4tJDgjdnA@mail.gmail.com>

On Fri, Nov 27, 2015 at 8:43 PM, justin bloomer via Python-list
<python-list at python.org> wrote:
> Your program should contain a function that:
> 1. Seeks input from the user (via the keyboard);
> 2. To build a list of student exam results;
> 3. For each student their name (first and last), student number, and mark
> out of 100 should be captured;
> 4. For full marks regular expressions or similar mechanisms should be used
> to ensure the data appears valid.

I suggest you start by opening up a programmer's editor and saving an
empty file under the name "examresults.py". Then take your keyboard in
hand, and start writing code. The above text would make a good set of
"stub comments" - notes to indicate what parts of code you still need
to write - which you can progressively replace with actual code.

ChrisA


From lac at openend.se  Fri Nov 27 05:14:14 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 27 Nov 2015 11:14:14 +0100
Subject: Help with this program???
In-Reply-To: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
References: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
Message-ID: <201511271014.tARAEEJB025295@fido.openend.se>

In a message of Fri, 27 Nov 2015 01:43:53 -0800, justin bloomer via Python-list
 writes:
>Your program should contain a function that:
>1. Seeks input from the user (via the keyboard);
>2. To build a list of student exam results;
>3. For each student their name (first and last), student number, and mark
>out of 100 should be captured;
>4. For full marks regular expressions or similar mechanisms should be used
>to ensure the data appears valid.

Hello.

We don't do people's assignments for them.
However, over on the tutor mailing list,
https://mail.python.org/mailman/listinfo/tutor
we do help people who are learning Python.

You will have to post your code, along with any error messages
you get and explain what you were trying to do.

Laura




From bc at freeuk.com  Fri Nov 27 05:31:27 2015
From: bc at freeuk.com (BartC)
Date: Fri, 27 Nov 2015 10:31:27 +0000
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
In-Reply-To: <5657ad63$0$1600$c3e8da3$5496439d@news.astraweb.com>
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <5657ad63$0$1600$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <n39b9o$25t$1@dont-email.me>

On 27/11/2015 01:09, Steven D'Aprano wrote:
> On Thu, 26 Nov 2015 12:23 pm, BartC wrote:

[First-class functions]
>> The names are declared, but the names are rarely bound to anything else.
>> Functions are just called the same boring way they are in C.
>>
>> /They might as well be static definitions/.
>
> Sure. And that's probably true for, oh, I don't know, I'll be generous, and
> say that 95% of Python functions in use are of a straight-forward
> pseudo-static form, using no dynamic features.
>
> But it's the other 5% -- one in twenty -- that *shine*. They're the ones
> that do things that you can't do in Pascal or C except with the greatest of
> difficulty.

OK, you're worried about that 5%, I'm more concerned about the other 95%.

I'm not saying you shouldn't have dynamic functions at all, just that 
it's not necessary for 100% to be dynamic.

I understand now that they are dynamic because that is the only 
mechanism that Python has to create any function definition, even the 
boring, static ones.

Together with the ability to subsequently re-bind the function name to 
something else, that's a bit unfortunate because it makes it harder to 
identifier calls to those functions in order to streamline them, or even 
for someone to look at a bit of code and be sure whether that fn(a,b,c) 
is calling the function defined as 'fn' a few hundred lines earlier or 
something else entirely.

(MRAB mentioned Postscript, which also introduces functions using 
executable statements.

However, Postscript was designed to execute code on-the-fly being 
received a character at a time over a printer cable. It had a good excuse!)

> Because Pascal doesn't have first-class functions, you couldn't pass a
> function as an argument to another function. So the ODE solvers used a
> hard-coded function as the equation to be solved. So if you wanted to solve
> a particular equation, you had to *edit the source code of the program*,
> modifying that hard-coded function to match your equation, then re-compile,
> and then run the code. You couldn't just type in the equation you wanted to
> solve and run the code.

Wouldn't Python have the same problem? If the equation to be solved, or 
even the actual function to be executed, is input by the user, then 
doesn't that require whichever one of exec() or eval() it is that 
processes the source code?

> There's a lot to like about Pascal,

It was designed for teaching. The original language would have needed 
tweaking for use in general purpose programming.

> but gosh it sure is lacking in power. C
> at least has function pointers, which is a step up from Pascal, but still
> pretty weak and feeble. If functions are first class values in Python,
> Ruby, Lisp and others, they're second class values in C and third class in
> Pascal.

I think they are more first class in Lisp than they are in most other 
languages including Python. That doesn't stop Python still being jolly 
useful though...

-- 
Bartc


From jfong at ms4.hinet.net  Fri Nov 27 06:14:40 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Fri, 27 Nov 2015 03:14:40 -0800 (PST)
Subject: python response slow when running external DLL
In-Reply-To: <mailman.169.1448615930.20593.python-list@python.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
Message-ID: <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>

Peter Otten at 2015/11/27  UTC+8 5:19:17 PM wrote?

Hi! Peter, thanks for your prompt reply.

> What does var_status.set() do? If it writes to stdout you may just need to 
> flush().

   var_status is a StringVar which binds to a lable's textvariable. I use this label as the status bar to show message.

> Do you see the same behaviour when you replace mydll.SayHello() with 
> something simple like time.sleep(1)?

    I use time.sleep(3) to replace mydll.SayHello(), still get the same.

> As a general remark keep your test scripts as simple as possible. Example: 
> If 
> 
> import mydll
> print("Download...", end="")
> mydll.SayHello()
> print("OK")
> 
> showed the same behaviour it would be the ideal test script.

    I run the above statements in a test file, it works as expected. I can see "Download..." and then "OK".




From marko at pacujo.net  Fri Nov 27 06:30:54 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Fri, 27 Nov 2015 13:30:54 +0200
Subject: Late-binding of function defaults (was Re: What is a function
 parameter =[] for?)
References: <CAPTjJmpwjWnF=d6mpgbKS1biVLoR4APutgyH0n9t6CJ=Kh4dCg@mail.gmail.com>
 <mailman.484.1447964295.16136.python-list@python.org>
 <87d1v5emhl.fsf@elektro.pacujo.net>
 <564e6a62$0$1620$c3e8da3$5496439d@news.astraweb.com>
 <mailman.54.1448439359.20593.python-list@python.org>
 <565592e9$0$1615$c3e8da3$5496439d@news.astraweb.com>
 <n34cem$4l5$1@dont-email.me>
 <d1c4eaac-5f3d-4836-9b3e-1bdfee5f4f57@googlegroups.com>
 <n34qdc$sbp$1@dont-email.me>
 <mailman.95.1448484677.20593.python-list@python.org>
 <n35amf$21o$1@dont-email.me> <87k2p54tdr.fsf@elektro.pacujo.net>
 <n35dbc$ckb$1@dont-email.me>
 <565652e1$0$1619$c3e8da3$5496439d@news.astraweb.com>
 <n35mps$dv8$1@dont-email.me>
 <5657ad63$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <n39b9o$25t$1@dont-email.me>
Message-ID: <878u5jel1t.fsf@elektro.pacujo.net>

BartC <bc at freeuk.com>:

> I think [functions] are more first class in Lisp than they are in most
> other languages including Python.

Functions in Python and Lisp have the same status.

I would say that Python is one of the many modern Lisp derivatives. What
Python still lacks is:

 * A way to augment the language syntax on the fly. (How could I add an
   "until" statement to Python in my Python application?)

 * A unified syntax for code and data. (Why use braces for dictionaries
   instead of indentation?)


Marko


From __peter__ at web.de  Fri Nov 27 07:20:03 2015
From: __peter__ at web.de (Peter Otten)
Date: Fri, 27 Nov 2015 13:20:03 +0100
Subject: python response slow when running external DLL
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
Message-ID: <n39hpj$384$1@ger.gmane.org>

jfong at ms4.hinet.net wrote:

> Peter Otten at 2015/11/27  UTC+8 5:19:17 PM wrote?
> 
> Hi! Peter, thanks for your prompt reply.
> 
>> What does var_status.set() do? If it writes to stdout you may just need
>> to flush().
> 
>    var_status is a StringVar which binds to a lable's textvariable. I use
>    this label as the status bar to show message.

Can I conclude from the above that you are using tkinter? Widgets can only 
update when the event loop gets a chance to run. While a quick fix is to 
invoke update_idletasks() callbacks shouldn't generally contain long-running 
code that -- as you have seen -- will block the complete user interface.
 
>> Do you see the same behaviour when you replace mydll.SayHello() with
>> something simple like time.sleep(1)?
> 
>     I use time.sleep(3) to replace mydll.SayHello(), still get the same.
> 
>> As a general remark keep your test scripts as simple as possible.
>> Example: If
>> 
>> import mydll
>> print("Download...", end="")
>> mydll.SayHello()
>> print("OK")
>> 
>> showed the same behaviour it would be the ideal test script.
> 
>     I run the above statements in a test file, it works as expected. I can
>     see "Download..." and then "OK".
> 
> 

Quick-fix example:

#!/usr/bin/env python3
import tkinter as tk
import time

def download():
    var.set("Starting download...")
    root.update_idletasks()
    time.sleep(3)
    var.set("... done")


root = tk.Tk()
var = tk.StringVar()
label = tk.Label(root, textvariable=var)
label.pack()
button = tk.Button(root, text="Download", command=download)
button.pack()

root.mainloop()

A cleaner solution can indeed involve threads; you might adapt the approach 
from <http://effbot.org/zone/tkinter-threads.htm> (Python 2 code).




From denismfmcmahon at gmail.com  Fri Nov 27 07:28:09 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Fri, 27 Nov 2015 12:28:09 -0000 (UTC)
Subject: Help with this program???
References: <c3c2d9d0-d59c-489b-bf3e-9488b202225b@googlegroups.com>
Message-ID: <n39i8p$k01$1@dont-email.me>

On Fri, 27 Nov 2015 01:43:53 -0800, justin bloomer wrote:

> Your program should contain a function that:
> 1. Seeks input from the user (via the keyboard);
> 2. To build a list of student exam results;
> 3. For each student their name (first and last), student number, and
> mark out of 100 should be captured;
> 4. For full marks regular expressions or similar mechanisms should be
> used to ensure the data appears valid.

Try writing a function that does the following:

1. Seeks input from the user (via the keyboard);
2. Builds a list of student exam results;
3. Captures name (first and last), student number, and mark out of 100 
for each student;
4. Uses regular expressions or similar mechanisms to ensure the data 
appears valid.

-- 
Denis McMahon, denismfmcmahon at gmail.com


From lac at openend.se  Fri Nov 27 07:49:47 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 27 Nov 2015 13:49:47 +0100
Subject: python response slow when running external DLL
In-Reply-To: <n39hpj$384$1@ger.gmane.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <n39hpj$384$1@ger.gmane.org>
Message-ID: <201511271249.tARCnlsJ027820@fido.openend.se>

In a message of Fri, 27 Nov 2015 13:20:03 +0100, Peter Otten writes:

>A cleaner solution can indeed involve threads; you might adapt the approach 
>from <http://effbot.org/zone/tkinter-threads.htm> (Python 2 code).

But it is probably better to use threading

http://code.activestate.com/recipes/82965-threads-tkinter-and-asynchronous-io/

Laura


From delphicr at gmail.com  Fri Nov 27 07:52:58 2015
From: delphicr at gmail.com (RENISH RUDANI)
Date: Fri, 27 Nov 2015 18:22:58 +0530
Subject: Fwd: convert php in to python
In-Reply-To: <CAP9M=4B6oBxOG1g8E2WJSKEtCNV=WcowvU_EO7sU=eA3jaMF1w@mail.gmail.com>
References: <CAP9M=4B6oBxOG1g8E2WJSKEtCNV=WcowvU_EO7sU=eA3jaMF1w@mail.gmail.com>
Message-ID: <CAP9M=4BabE0gg5svMB5rQJacAK-vEGR7_4suaJQ45u9NqwHqaQ@mail.gmail.com>

Hi,

Please help me to convert this code in python.


*Thanks & Regards,*

*Renish Rudani*

*Action Speaks Louder than Words*


From steve at pearwood.info  Fri Nov 27 07:57:29 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Fri, 27 Nov 2015 23:57:29 +1100
Subject: What is a function parameter =[] for?
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
 <mailman.162.1448592976.20593.python-list@python.org>
Message-ID: <5658533c$0$1591$c3e8da3$5496439d@news.astraweb.com>

On Fri, 27 Nov 2015 01:56 pm, MRAB wrote:

> On 2015-11-27 02:44, Steven D'Aprano wrote:

>> The PyPy implementation has to take special actions to preserve the ID
>> across object recreations. That is what I mean by "faked".
>>
> You could argue that it _does_ continue to exist, it just changes its
> form...

*Something* continues to exist, but it is no longer an object.

I like Chris' analogy of it being like quantum mechanics -- the *object*
isn't guaranteed to exist except when you try to access it, until then you
don't know what form it will take at any instance.



-- 
Steven



From lac at openend.se  Fri Nov 27 08:24:36 2015
From: lac at openend.se (Laura Creighton)
Date: Fri, 27 Nov 2015 14:24:36 +0100
Subject: What is a function parameter =[] for?
In-Reply-To: <5658533c$0$1591$c3e8da3$5496439d@news.astraweb.com>
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
 <mailman.162.1448592976.20593.python-list@python.org>
 <5658533c$0$1591$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <201511271324.tARDOafP028282@fido.openend.se>

In a message of Fri, 27 Nov 2015 23:57:29 +1100, "Steven D'Aprano" writes:
>On Fri, 27 Nov 2015 01:56 pm, MRAB wrote:
>
>> On 2015-11-27 02:44, Steven D'Aprano wrote:
>
>>> The PyPy implementation has to take special actions to preserve the ID
>>> across object recreations. That is what I mean by "faked".
>>>
>> You could argue that it _does_ continue to exist, it just changes its
>> form...
>
>*Something* continues to exist, but it is no longer an object.
>
>I like Chris' analogy of it being like quantum mechanics -- the *object*
>isn't guaranteed to exist except when you try to access it, until then you
>don't know what form it will take at any instance.

I think it's just another instance of Just-In-Time Manufacturing
https://en.wikipedia.org/wiki/Just-in-time_manufacturing

"As soon as you need a object, we'll have one ready". :)

Laura


From rosuav at gmail.com  Fri Nov 27 08:29:49 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sat, 28 Nov 2015 00:29:49 +1100
Subject: What is a function parameter =[] for?
In-Reply-To: <201511271324.tARDOafP028282@fido.openend.se>
References: <mailman.33.1448398558.20593.python-list@python.org>
 <n32jqq$k4j$1@dont-email.me>
 <mailman.35.1448400323.20593.python-list@python.org>
 <56550273$0$1585$c3e8da3$5496439d@news.astraweb.com>
 <mailman.64.1448445391.20593.python-list@python.org>
 <5655f27b$0$1614$c3e8da3$5496439d@news.astraweb.com>
 <w2dh9k9bjhq.fsf@daphne.csail.mit.edu>
 <mailman.109.1448504727.20593.python-list@python.org>
 <w2dd1uxbd1c.fsf@daphne.csail.mit.edu>
 <6imd5b9it55sucrcl95o95tppro7errfsi@4ax.com>
 <5657b30d$0$1600$c3e8da3$5496439d@news.astraweb.com>
 <mailman.160.1448588423.20593.python-list@python.org>
 <5657c376$0$1618$c3e8da3$5496439d@news.astraweb.com>
 <mailman.162.1448592976.20593.python-list@python.org>
 <5658533c$0$1591$c3e8da3$5496439d@news.astraweb.com>
 <201511271324.tARDOafP028282@fido.openend.se>
Message-ID: <CAPTjJmoEiT68aMwMpuYVT+Cenyd=bGJoRj0ZunOrJ9f-2QWn=A@mail.gmail.com>

On Sat, Nov 28, 2015 at 12:24 AM, Laura Creighton <lac at openend.se> wrote:
> I think it's just another instance of Just-In-Time Manufacturing
> https://en.wikipedia.org/wiki/Just-in-time_manufacturing
>
> "As soon as you need a object, we'll have one ready". :)

Just-In-Time Quantum Manufacturing: "As soon as you need an electron,
we'll have the same one ready!"

ChrisA


From paul.hermeneutic at gmail.com  Fri Nov 27 11:45:35 2015
From: paul.hermeneutic at gmail.com (paul.hermeneutic at gmail.com)
Date: Fri, 27 Nov 2015 09:45:35 -0700
Subject: fexit: file transfer of ANY size
In-Reply-To: <n36vf2$86s$1@news2.informatik.uni-stuttgart.de>
References: <n36vf2$86s$1@news2.informatik.uni-stuttgart.de>
Message-ID: <CAJ4+4ar8oB6+MJmS-xcEKJxNn824LQdvuwvFp6B7ofdtnh9y2g@mail.gmail.com>

> And what is F*EX?
> ==> Frams' Fast File EXchange, a service for transfering files of ANY size
> from any user A to any user B in the internet.
> For details see: http://fex.rus.uni-stuttgart.de/
>
> I am now looking for beta testers. If you are interested, send me a mail.

Can you tell us a git or svn repository from which the kit is available?
Or, is this a proprietary product?


From framstag at rus.uni-stuttgart.de  Fri Nov 27 13:32:29 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Fri, 27 Nov 2015 18:32:29 +0000 (UTC)
Subject: fexit: file transfer of ANY size
References: <n36vf2$86s$1@news2.informatik.uni-stuttgart.de>
 <mailman.178.1448642737.20593.python-list@python.org>
Message-ID: <n3a7jt$4mv$1@news2.informatik.uni-stuttgart.de>

paul.hermeneutic at gmail.com wrote:

> > I am now looking for beta testers. If you are interested, send me a mail.
> 
> Can you tell us a git or svn repository from which the kit is available?

Available via email request.


> Or, is this a proprietary product?

No.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From real-not-anti-spam-address at apple-juice.co.uk  Fri Nov 27 19:37:21 2015
From: real-not-anti-spam-address at apple-juice.co.uk (D.M. Procida)
Date: Sat, 28 Nov 2015 00:37:21 +0000
Subject: Python 3 virtualenvs
Message-ID: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>

I have a new installation of Debian Jessie, with Python 2.7 and 3.4
installed.

I want to use Python 3.4 by default for most things, so I want
virtualenv to create Python 3.4 virtualenvs unless I ask it to
otherwise.

It turns out that this seems to be inordinately complex.

The best solution I have come up with is to alias virtualenv to
'virtualenv -p python3.5', which seems really ugly and clunky.

Then I discover things like
<http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualenv-vs-virtualenv-and-python-3>
and realise it's not just me, it really is a nasty mess and nobody seems
to understand what's going on.

Daniele


From lac at openend.se  Fri Nov 27 20:09:20 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 02:09:20 +0100
Subject: Python 3 virtualenvs
In-Reply-To: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
Message-ID: <201511280109.tAS19KpM009020@fido.openend.se>

In a message of Sat, 28 Nov 2015 00:37:21 +0000, D.M. Procida writes:
>I have a new installation of Debian Jessie, with Python 2.7 and 3.4
>installed.
>
>I want to use Python 3.4 by default for most things, so I want
>virtualenv to create Python 3.4 virtualenvs unless I ask it to
>otherwise.
>
>It turns out that this seems to be inordinately complex.
>
>The best solution I have come up with is to alias virtualenv to
>'virtualenv -p python3.5', which seems really ugly and clunky.

This will get you python3.5 which I infinitely prefer over 3.4. 
But you said you wanted to use 3.4 ...

>Then I discover things like
><http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualenv-vs-virtualenv-and-python-3>
>and realise it's not just me, it really is a nasty mess and nobody seems
>to understand what's going on.
>
>Daniele

What I found out.
https://bugs.python.org/issue25151
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732703
https://bugs.python.org/issue25152
https://bugs.python.org/issue25154

pyenv is going away.  use python -m venv instead, if you want a 
venv.  You will never (unless somebody does a backport, which seems
very unlikley) be able to get a venv with 2.7.

I've long ago aliased virtualenv to v, so things aren't as clunky
for me.

Laura


From real-not-anti-spam-address at apple-juice.co.uk  Fri Nov 27 20:35:54 2015
From: real-not-anti-spam-address at apple-juice.co.uk (D.M. Procida)
Date: Sat, 28 Nov 2015 01:35:54 +0000
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <mailman.179.1448672987.20593.python-list@python.org>
Message-ID: <1mekoqg.11rv2hi1owcmgjN%real-not-anti-spam-address@apple-juice.co.uk>

Laura Creighton <lac at openend.se> wrote:

> In a message of Sat, 28 Nov 2015 00:37:21 +0000, D.M. Procida writes:
> >I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> >installed.
> >
> >I want to use Python 3.4 by default for most things, so I want
> >virtualenv to create Python 3.4 virtualenvs unless I ask it to
> >otherwise.
> >
> >It turns out that this seems to be inordinately complex.
> >
> >The best solution I have come up with is to alias virtualenv to
> >'virtualenv -p python3.5', which seems really ugly and clunky.
> 
> This will get you python3.5 which I infinitely prefer over 3.4. 
> But you said you wanted to use 3.4 ...

Typo!

> >Then I discover things like
> ><http://askubuntu.com/questions/603935/pyvenv-vs-venv-vs-python-virtualen
> >v-vs-virtualenv-and-python-3> and realise it's not just me, it really is
> >a nasty mess and nobody seems to understand what's going on.

> What I found out.
> https://bugs.python.org/issue25151
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=732703
> https://bugs.python.org/issue25152
> https://bugs.python.org/issue25154

Good lord.

> I've long ago aliased virtualenv to v, so things aren't as clunky
> for me.

I'll stick with virtualenv as an alias to virtualenv -p python3.5.
 
Thanks,

Daniele


From ben+python at benfinney.id.au  Fri Nov 27 20:42:30 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Sat, 28 Nov 2015 12:42:30 +1100
Subject: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <201511280109.tAS19KpM009020@fido.openend.se>
Message-ID: <85lh9i99x5.fsf_-_@benfinney.id.au>

Laura Creighton <lac at openend.se> writes:

> [?] python3.5 which I infinitely prefer over 3.4. 

That's strong language :-)

Laura ? and anyone else ? what in your opinion are the best improvements
brought by Python 3.5 (over Python 3.4)?

-- 
 \     ?DRM doesn't inconvenience [lawbreakers] ? indeed, over time it |
  `\     trains law-abiding users to become [lawbreakers] out of sheer |
_o__)                        frustration.? ?Charles Stross, 2010-05-09 |
Ben Finney



From lac at openend.se  Fri Nov 27 21:23:23 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 03:23:23 +0100
Subject: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)
In-Reply-To: <85lh9i99x5.fsf_-_@benfinney.id.au>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <201511280109.tAS19KpM009020@fido.openend.se>
 <85lh9i99x5.fsf_-_@benfinney.id.au>
Message-ID: <201511280223.tAS2NNuj010015@fido.openend.se>

In a message of Sat, 28 Nov 2015 12:42:30 +1100, Ben Finney writes:
>Laura Creighton <lac at openend.se> writes:
>
>> [?] python3.5 which I infinitely prefer over 3.4. 
>
>That's strong language :-)
>
>Laura ? and anyone else ? what in your opinion are the best improvements
>brought by Python 3.5 (over Python 3.4)?

The interactive console started working again.
https://bugs.python.org/issue23441

Laura


From rhills at medimorphosis.com.au  Fri Nov 27 21:35:16 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Sat, 28 Nov 2015 10:35:16 +0800
Subject: Find relative url in mixed text/html
Message-ID: <565912E4.4000908@medimorphosis.com.au>

Hi,

For my sins I am migrating a volunteer association forum from one
platform (WebWiz) to another (phpBB).  I am (I hope) 95% of the way
through the process.

Posts to our original forum comprise a soup of plain text, HTML and
BBCodes.  A post */may/* include links done as either standard HTML
links ( <a href=... ), BBCode links ( [url]http://... [/url] ) or
sometimes just text: ( http://blah.blah.com.au or even just
www.blah.blah.com.au ).

In my conversion process, I am trying to identify cross-links (links
from one post on the forum to another) so I can convert them to links
that will work in the new forum.

My current code uses a Regular Expression (yes, I read the recent posts
on this forum about regex and HTML!) to pull out "absolute" links (
starting with http:// ) and then I use Python to identify and convert
the specific links I am interested in.  However, the forum also contains
"cross-links" done using relative links and I'm unsure how best to
proceed with that one.  Googling so far has not been helpful, but that
might be me using the wrong search terms. 

Some examples of what I am talking about are:

    Post fragment containing an "Absolute" cross-link:

    <br />ive made a new thread:
    <br />http://www.aeva.asn.au/forums/forum_posts.asp?TID=316&PID=1958#1958
    <br />

    converts to:

    <br />
    <br />ive made a new thread:
    <br />/viewtopic.php?t=316&p=1958#1958

    Post fragment containing a "Relative" cross-link:

    <font size="3"><u>Battery Management System</u></font><br /><a href="/forum_posts.asp?TID=980&PID=15479#15479" target="_blank" rel="nofollow">Veroboard prototype</a><br />

    Needs converting to:

    <font size="3"><u>Battery Management System</u></font><br /><a href="/viewtopic.php?p=15479&t=980#15479" target="_blank" rel="nofollow">Veroboard prototype</a><br />

So, my question is:  What is the best way to extract a list of "relative
links" from mixed text/html that I can then walk through to identify the
specific ones I want to convert?

Note, in the beginning of this project, I looked at using "Beautiful
Soup" but my reading and limited testing lead me to believe that it is
designed for well-formed HTML/XML and therefore was unsuitable for the
text/html soup I have.  If that belief is incorrect, I'd be grateful for
general tips about using Beautiful Soup in this scenario...

TIA,

-- 
Rob Hills
Waikiki, Western Australia



From no.email at nospam.invalid  Sat Nov 28 00:11:58 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Fri, 27 Nov 2015 21:11:58 -0800
Subject: Find relative url in mixed text/html
References: <mailman.182.1448678122.20593.python-list@python.org>
Message-ID: <8737vqyag1.fsf@jester.gateway.pace.com>

Rob Hills <rhills at medimorphosis.com.au> writes:
> Note, in the beginning of this project, I looked at using "Beautiful
> Soup" but my reading and limited testing lead me to believe that it is
> designed for well-formed HTML/XML and therefore was unsuitable for the
> text/html soup I have.  If that belief is incorrect, I'd be grateful for
> general tips about using Beautiful Soup in this scenario...

Beautiful Soup can deal with badly formed HTML pretty well, or at least
it could in earlier versions.  It gives you several different parsing
options to choose from now.  I think the default is lxml which is fast
but maybe more strict.  Check what the others are and see if a loose
slow one is still there.  It really is pretty slow so plan on a big
computation task if you're converting a large forum.

phpBB gets a bad rap that's maybe well-deserved but I don't know what to
suggest instead.


From snailcoder at retrosite.invalid  Sat Nov 28 02:07:32 2015
From: snailcoder at retrosite.invalid (Grobu)
Date: Sat, 28 Nov 2015 08:07:32 +0100
Subject: Find relative url in mixed text/html
In-Reply-To: <mailman.182.1448678122.20593.python-list@python.org>
References: <mailman.182.1448678122.20593.python-list@python.org>
Message-ID: <n3bjmq$pdi$1@dont-email.me>

On 28/11/15 03:35, Rob Hills wrote:
> Hi,
>
> For my sins I am migrating a volunteer association forum from one
> platform (WebWiz) to another (phpBB).  I am (I hope) 95% of the way
> through the process.
>
> Posts to our original forum comprise a soup of plain text, HTML and
> BBCodes.  A post */may/* include links done as either standard HTML
> links ( <a href=... ), BBCode links ( [url]http://... [/url] ) or
> sometimes just text: ( http://blah.blah.com.au or even just
> www.blah.blah.com.au ).
>
> In my conversion process, I am trying to identify cross-links (links
> from one post on the forum to another) so I can convert them to links
> that will work in the new forum.
>
> My current code uses a Regular Expression (yes, I read the recent posts
> on this forum about regex and HTML!) to pull out "absolute" links (
> starting with http:// ) and then I use Python to identify and convert
> the specific links I am interested in.  However, the forum also contains
> "cross-links" done using relative links and I'm unsure how best to
> proceed with that one.  Googling so far has not been helpful, but that
> might be me using the wrong search terms.
>
> Some examples of what I am talking about are:
>
>      Post fragment containing an "Absolute" cross-link:
>
>      <br />ive made a new thread:
>      <br />http://www.aeva.asn.au/forums/forum_posts.asp?TID=316&PID=1958#1958
>      <br />
>
>      converts to:
>
>      <br />
>      <br />ive made a new thread:
>      <br />/viewtopic.php?t=316&p=1958#1958
>
>      Post fragment containing a "Relative" cross-link:
>
>      <font size="3"><u>Battery Management System</u></font><br /><a href="/forum_posts.asp?TID=980&PID=15479#15479" target="_blank" rel="nofollow">Veroboard prototype</a><br />
>
>      Needs converting to:
>
>      <font size="3"><u>Battery Management System</u></font><br /><a href="/viewtopic.php?p=15479&t=980#15479" target="_blank" rel="nofollow">Veroboard prototype</a><br />
>
> So, my question is:  What is the best way to extract a list of "relative
> links" from mixed text/html that I can then walk through to identify the
> specific ones I want to convert?
>
> Note, in the beginning of this project, I looked at using "Beautiful
> Soup" but my reading and limited testing lead me to believe that it is
> designed for well-formed HTML/XML and therefore was unsuitable for the
> text/html soup I have.  If that belief is incorrect, I'd be grateful for
> general tips about using Beautiful Soup in this scenario...
>
> TIA,
>

Hi Rob

Is it safe to assume that all the relative (cross) links take one of the 
following forms? :

	http://www.aeva.asn.au/forums/forum_posts.asp
	www.aeva.asn.au/forums/forum_posts.asp
	/forums/forum_posts.asp
	/forum_posts.asp (are you really sure about this one?)

If so, and if your goal boils down to converting all instances of old 
style URLs to new style ones regardless of the context where they 
appear, why would a regex fail to meet your needs?




From songofacandy at gmail.com  Sat Nov 28 02:17:17 2015
From: songofacandy at gmail.com (INADA Naoki)
Date: Sat, 28 Nov 2015 16:17:17 +0900
Subject: Faviourite improvements in Python 3.5 (was: Python 3 virtualenvs)
In-Reply-To: <85lh9i99x5.fsf_-_@benfinney.id.au>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <201511280109.tAS19KpM009020@fido.openend.se>
 <85lh9i99x5.fsf_-_@benfinney.id.au>
Message-ID: <CAEfz+TxCG5PkWpDGKw3eMHDN4KK6V6C=UheFCt8Dnnbdrwm0HQ@mail.gmail.com>

OrderedDict is now faster and efficient.

On Sat, Nov 28, 2015 at 10:42 AM, Ben Finney <ben+python at benfinney.id.au>
wrote:

> Laura Creighton <lac at openend.se> writes:
>
> > [?] python3.5 which I infinitely prefer over 3.4.
>
> That's strong language :-)
>
> Laura ? and anyone else ? what in your opinion are the best improvements
> brought by Python 3.5 (over Python 3.4)?
>
> --
>  \     ?DRM doesn't inconvenience [lawbreakers] ? indeed, over time it |
>   `\     trains law-abiding users to become [lawbreakers] out of sheer |
> _o__)                        frustration.? ?Charles Stross, 2010-05-09 |
> Ben Finney
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
INADA Naoki  <songofacandy at gmail.com>


From jfong at ms4.hinet.net  Sat Nov 28 02:37:58 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Fri, 27 Nov 2015 23:37:58 -0800 (PST)
Subject: python response slow when running external DLL
In-Reply-To: <mailman.173.1448626828.20593.python-list@python.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
Message-ID: <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>

Peter Otten at 2015/11/27 UTC+8 8:20:54PM wrote?

> Quick-fix example:
> def download():
>     var.set("Starting download...")
>     root.update_idletasks()
>     time.sleep(3)
>     var.set("... done")

Thanks, Peter, The update_idletasks() works. In my trivial program it's easy to apply for there are only two places call the DLL function.

> A cleaner solution can indeed involve threads; you might adapt the approach 
> from <http://effbot.org/zone/tkinter-threads.htm> (Python 2 code).

Using thread is obviously more logical. I think my mistake was the "while busy:  pass" loop which makes no sense because it blocks the main thread, just as the time.sleep() does. That's why in your link (and Laura's too) the widget.after() scheduling was used for this purpose.

>From what I had learned here, the other way I can do is making the codes modified as follows. It will get ride of the "result" and "busy" global variables, but it also makes the codes looks a little ugly. I think I will take the update_idletasks() way in this porting for it seems more simpler, and can be used on thread or non-thread calling. Thank you again.
    .....
    .....
    #do the rest
    var_status.set('Download...')
    _thread.start_new_thread(td_download, ())  #must use threading

def td_download():
    result = mydll.SayHello()
    if result:
        var_status.set("Download Fail at %s" % hex(result))
        showerror('Romter', 'Download Fail')
    else:
        var_status.set('Download OK')            
        showinfo('Romter', 'Download OK')



From __peter__ at web.de  Sat Nov 28 05:13:38 2015
From: __peter__ at web.de (Peter Otten)
Date: Sat, 28 Nov 2015 11:13:38 +0100
Subject: python response slow when running external DLL
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
 <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>
Message-ID: <n3buoh$3r1$1@ger.gmane.org>

jfong at ms4.hinet.net wrote:

> Peter Otten at 2015/11/27 UTC+8 8:20:54PM wrote?
> 
>> Quick-fix example:
>> def download():
>>     var.set("Starting download...")
>>     root.update_idletasks()
>>     time.sleep(3)
>>     var.set("... done")
> 
> Thanks, Peter, The update_idletasks() works. In my trivial program it's
> easy to apply for there are only two places call the DLL function.
> 
>> A cleaner solution can indeed involve threads; you might adapt the
>> approach from <http://effbot.org/zone/tkinter-threads.htm> (Python 2
>> code).
> 
> Using thread is obviously more logical. I think my mistake was the "while
> busy:  pass" loop which makes no sense because it blocks the main thread,
> just as the time.sleep() does. That's why in your link (and Laura's too)
> the widget.after() scheduling was used for this purpose.

No, the point of both recipes is that tkinter operations are only ever 
invoked from the main thread. The main thread has polling code that 
repeatedly looks if there are results from the helper thread. As far I 
understand the polling method has the structure

f():
   # did we get something back from the other thread?
   # a queue is used to avoid race conditions

   # if yes react.
   # var_status.set() goes here

   # reschedule f to run again in a few millisecs; 
   # that's what after() does
 
> From what I had learned here, the other way I can do is making the codes
> modified as follows. It will get ride of the "result" and "busy" global
> variables, but it also makes the codes looks a little ugly. I think I will
> take the update_idletasks() way in this porting for it seems more simpler,
> and can be used on thread or non-thread calling. Thank you again.
>     .....
>     .....
>     #do the rest
>     var_status.set('Download...')
>     _thread.start_new_thread(td_download, ())  #must use threading
> 
> def td_download():
>     result = mydll.SayHello()
>     if result:
>         var_status.set("Download Fail at %s" % hex(result))
>         showerror('Romter', 'Download Fail')
>     else:
>         var_status.set('Download OK')
>         showinfo('Romter', 'Download OK')

As td_download() runs in the other thread the var_status.set() methods are 
problematic.

Another complication that inevitably comes with concurrency: what if the 
user triggers another download while one download is already running? If you 
don't keep track of all downloads the message will already switch to 
"Download OK" while one download is still running.



From framstag at rus.uni-stuttgart.de  Sat Nov 28 05:29:55 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Sat, 28 Nov 2015 10:29:55 +0000 (UTC)
Subject: askopenfilename() (was: Re: non-blocking getkey?)
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:
> eryksun <eryksun at gmail.com> wrote:
> > On Thu, Nov 19, 2015 at 10:31 AM, Michael Torrie <torriem at gmail.com> wrote:
> > > One windows it might be possible to use the win32 api to enumerate the
> > > windows, find your console window and switch to it.
> > 
> > You can call GetConsoleWindow [1] and then SetForegroundWindow [2].
> (...)
> 
> great, this works! Thanks!

One of my Windows test users reports, that the file dialog window of
askopenfilename() starts behind the console window and has no focus.
On Linux (XFCE) I do not have this problem.

I start it with:

  Tk().withdraw()
  file = askopenfilename(title='select a file',initialdir=HOME)
  set_window_focus() # give focus back to console window

Can one force askopenfilename() to start in foreground with focus?

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From lac at openend.se  Sat Nov 28 05:51:55 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 11:51:55 +0100
Subject: python response slow when running external DLL
In-Reply-To: <n3buoh$3r1$1@ger.gmane.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
 <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>
 <n3buoh$3r1$1@ger.gmane.org>
Message-ID: <201511281051.tASAptQQ016625@fido.openend.se>

In a message of Sat, 28 Nov 2015 11:13:38 +0100, Peter Otten writes:
>jfong at ms4.hinet.net wrote:
>> Using thread is obviously more logical. I think my mistake was the "while
>> busy:  pass" loop which makes no sense because it blocks the main thread,
>> just as the time.sleep() does. That's why in your link (and Laura's too)
>> the widget.after() scheduling was used for this purpose.

I never saw the reply that Peter is replying to.
The threading module constructs a higher level interface on top of the
low level thread module.  Thus it is the preferred way to go for
standard Python code -- and even Fredrik's recipe contains the
line:
	import thread # should use the threading module instead!

Laura



From jeanpierreda at gmail.com  Sat Nov 28 06:31:14 2015
From: jeanpierreda at gmail.com (Devin Jeanpierre)
Date: Sat, 28 Nov 2015 03:31:14 -0800
Subject: Looking for ideas to improve library API
In-Reply-To: <CABMb9GtR_WVngUUmNAVP83vXJbUZK40REfUBeBpCn3XL2YFaPw@mail.gmail.com>
References: <CABMb9Gu+m9cJXQavXwxc0iouhsKsFSFKVvepLXhJcorc8aUkRw@mail.gmail.com>
 <CABicbJJkNCTW6PAWw_P5mQmHAwysJaG49N8C+zLV9vKQkWB8_Q@mail.gmail.com>
 <CABMb9GtR_WVngUUmNAVP83vXJbUZK40REfUBeBpCn3XL2YFaPw@mail.gmail.com>
Message-ID: <CABicbJKi=ZuCNhw2DTgn0F43=EYFvctjQiiRyyoceQA-QV7BvA@mail.gmail.com>

Documentation is all you can do.

-- Devin

On Thu, Nov 26, 2015 at 5:35 AM, Chris Lalancette <clalancette at gmail.com> wrote:
> On Thu, Nov 26, 2015 at 7:46 AM, Devin Jeanpierre
> <jeanpierreda at gmail.com> wrote:
>> Why not take ownership of the file object, instead of requiring users
>> to manage lifetimes?
>
> Yeah, I've kind of been coming to this conclusion.  So my question
> then becomes: how do I "take ownership" of it?  I already keep a
> reference to it, but how would I signal to the API user that they
> should no longer use that file object (other than documentation)?
>
> Thanks,
> Chris


From auriocus at gmx.de  Sat Nov 28 06:45:18 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 28 Nov 2015 12:45:18 +0100
Subject: askopenfilename()
In-Reply-To: <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hfe1$n3l$1@dont-email.me> <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3c3vu$a8t$1@dont-email.me>

Am 28.11.15 um 11:29 schrieb Ulli Horlacher:
> One of my Windows test users reports, that the file dialog window of
> askopenfilename() starts behind the console window and has no focus.
> On Linux (XFCE) I do not have this problem.
>
> I start it with:
>
>    Tk().withdraw()
>    file = askopenfilename(title='select a file',initialdir=HOME)
>    set_window_focus() # give focus back to console window
>
> Can one force askopenfilename() to start in foreground with focus?

I can't test it right now, but I think it /should/ go into the 
foreground by itself. For a toplevel window, which you create manually, 
there is a lift() method which asks the OS to move the window to the 
top. But on Windows, this file dialog is a native call and cannot be 
influenced that much.

I see two thingd:

1) Tk().withdraw()

- this seems odd to me, because you don't keep a reference to the Tk 
object around. Better do

	root=Tk()
	roo.withdraw()

2) Maybe it helps if you inject an update() after the withdraw(), maybe not

	root.update()

3) I can confirm, that also on OSX the file dialog does not raise above 
the console window, though it is not as bad because the dialog window is 
muhc bigger then the console window.

I think that you are curing a lot of symptoms with the focus setting to 
the console etc. Many problems would simply go away if you wrote the 
whole thing as a GUI program. If I understand correctly, what you want - 
a program to select files and folders to upload to your server - then 
this would not be that much more work than the CLI with input() which 
you are writing, and definitely less work to get it correct than the 
plastering of the symptoms.

For example, a very simple approach would use a listbox with a + and a - 
button. upon hitting - (or the delete key), you delete the selected 
entries. Upon hitting +, you pop up the file selection dialog. upon 
hitting a Go button, you send the files to the server. A minimalistic 
version of it is included below. That is less then 50 lines of code, 
including comments, without all the focus problems, providing a standard 
desktop GUI metaphor. I haven't seen your command line code, but I doubt 
that it is significantly simpler.

Of course, the code below can still use a great deal of polishing, like 
scrollbars for the listbox, allowing multiple selection both for the 
file dialog and the listbox, nice icons for the buttons, trapping the 
close button on the main window with an "are you sure?"-type question, 
maybe wrapping it up in a class, a progress bar during the upload and a 
way to interrupt it... which is left as an exercise to the reader.

	Christian

=================================
import Tkinter as tk, tkFileDialog as fd, ttk
from Tkinter import N,S,W,E
# create one ttk::frame to fill the main window
root=tk.Tk()
main=ttk.Frame(master=root)
# tell the pack geometry manager to completely
# fill the toplevel with this frame
main.pack(fill=tk.BOTH, expand=1)

# now create a listbox and a button frame
lb=tk.Listbox(master=main)
bf=ttk.Frame(master=main)

# use the grid manager to stack them, whereby
# the listbox should expand
lb.grid(row=0, column=0, sticky=(N,S,E,W))
bf.grid(row=1, column=0, sticky=(N,S,E,W))
main.rowconfigure(0, weight=1)
main.columnconfigure(0, weight=1)

def addfile():
	filename=fd.askopenfilename()
	if filename:
		lb.insert(tk.END, filename)

def remove(*args):
	sel=lb.curselection()
	if sel:
		lb.delete(sel)

def submit():
	print("Submitting files:")
	for filename in lb.get(0,tk.END):
		print("Sending %s"%filename)

# create the three buttons
btnplus=ttk.Button(master=bf, text="+", command=addfile)
btnminus=ttk.Button(master=bf, text="-", command=remove)
btngo=ttk.Button(master=bf, text="Submit", command=submit)

btnplus.pack(side=tk.LEFT)
btnminus.pack(side=tk.LEFT)
btngo.pack(side=tk.LEFT)

# bind also the delete and Backspace keys
lb.bind('<Delete>', remove)
lb.bind('<BackSpace>', remove)

root.mainloop()
===================================================





From framstag at rus.uni-stuttgart.de  Sat Nov 28 07:48:43 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Sat, 28 Nov 2015 12:48:43 +0000 (UTC)
Subject: askopenfilename()
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@net.de> <n2ia83$icf$2@nuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de> <n3c3vu$a8t$1@dont-email.me>
Message-ID: <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de>

Christian Gollwitzer <auriocus at gmx.de> wrote:

> Am 28.11.15 um 11:29 schrieb Ulli Horlacher:
> > One of my Windows test users reports, that the file dialog window of
> > askopenfilename() starts behind the console window and has no focus.
> > On Linux (XFCE) I do not have this problem.
> >
> > I start it with:
> >
> >    Tk().withdraw()
> >    file = askopenfilename(title='select a file',initialdir=HOME)
> >    set_window_focus() # give focus back to console window
> >
> > Can one force askopenfilename() to start in foreground with focus?
> 
> I can't test it right now, but I think it /should/ go into the 
> foreground by itself. 

This is what I think, too :-)
But my test user reports me, it is not so.


> I see two thingd:
> 
> 1) Tk().withdraw()
> 
> - this seems odd to me, because you don't keep a reference to the Tk 
> object around. 

I thought, I need it for Tk initialization.
But true, it is superfluous


> I think that you are curing a lot of symptoms with the focus setting to 
> the console etc.

This is done after the file selection window is closed. This works.


> Many problems would simply go away if you wrote the whole thing as a GUI
> program.

Too much hassle.
The predecessor was a Perl/Tk program and I have had to invest 90% of the 
programming work into the GUI handling. No fun at all.
Now, with fexit in Python, I skipped most of these problems.
The only GUI part is the file selection.


> If I understand correctly, what you want - a program to select files and
> folders to upload to your server 

This is only one of the tasks. The main menu looks:

[s]  send a file or directory
[g]  get a file
[c]  change login data (user, server, auth-ID)
[l]  login with webbrowser
[u]  update fexit
[h]  help
[q]  quit

(with more features to come in the future)

And the CLI:

framstag at juhu:~: ./fexit.py -h
usage: fexit [-C "comment"] [-a container] file(s) recipient[,...]
example: fexit flupp.avi framstag at rus.uni-stuttgart.de
example: fexit -C "more data" -a labdata *.png x1 at flupp.org,x2 at flupp.org

usage: fexit FEX-download-URL
example: fexit http://fex.rus.uni-stuttgart.de/fop/jHn34yp7/flupp.avi


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From jon+usenet at unequivocal.co.uk  Sat Nov 28 08:29:54 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Sat, 28 Nov 2015 13:29:54 -0000 (UTC)
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
Message-ID: <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk> wrote:
> I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> installed.
>
> I want to use Python 3.4 by default for most things, so I want
> virtualenv to create Python 3.4 virtualenvs unless I ask it to
> otherwise.
>
> It turns out that this seems to be inordinately complex.

sudo apt-get remove python-virtualenv
sudo apt-get install python3-virtualenv


From auriocus at gmx.de  Sat Nov 28 08:34:27 2015
From: auriocus at gmx.de (Christian Gollwitzer)
Date: Sat, 28 Nov 2015 14:34:27 +0100
Subject: askopenfilename()
In-Reply-To: <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@net.de> <n2ia83$icf$2@nuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de> <n3c3vu$a8t$1@dont-email.me>
 <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3cacj$o5$1@dont-email.me>

Am 28.11.15 um 13:48 schrieb Ulli Horlacher:
> Christian Gollwitzer <auriocus at gmx.de> wrote:
>> Many problems would simply go away if you wrote the whole thing as a GUI
>> program.
>
> Too much hassle.
> The predecessor was a Perl/Tk program and I have had to invest 90% of the
> programming work into the GUI handling. No fun at all.

As I see it, the program consists only of user interface - or is there 
any "algorithm" working behinds the scenes? Maybe you could pass the 
task on to somebody who enjoys GUI programming?

> Now, with fexit in Python, I skipped most of these problems.
> The only GUI part is the file selection.
>
>
>> If I understand correctly, what you want - a program to select files and
>> folders to upload to your server
>
> This is only one of the tasks. The main menu looks:
>
> [s]  send a file or directory
> [g]  get a file
> [c]  change login data (user, server, auth-ID)
> [l]  login with webbrowser
> [u]  update fexit
> [h]  help
> [q]  quit

All of this is easily integrated into a GUI like the one I posted (have 
you tried it?), either as a button or as a menu entry. IMO the most 
common GUI pattern for this kind of thing is a side-by-side view of the 
directories on the server and on the client, and a button (or 
drag'n'drop) to move files between both views. I understand this is not 
as easy as the script posted by me - nonetheless quite doable. For an 
experienced GUI script writer it'll take a weekend to get the basics 
running.

> (with more features to come in the future)
>
> And the CLI:
>
> framstag at juhu:~: ./fexit.py -h
> usage: fexit [-C "comment"] [-a container] file(s) recipient[,...]
> example: fexit flupp.avi framstag at rus.uni-stuttgart.de
> example: fexit -C "more data" -a labdata *.png x1 at flupp.org,x2 at flupp.org
>
> usage: fexit FEX-download-URL
> example: fexit http://fex.rus.uni-stuttgart.de/fop/jHn34yp7/flupp.avi
>

This part should probably stay as it is. For a command line tool, an 
scp-like interface seems well-fitting. But for guided user input, an 
interface which prompts the user for input has never been a good 
solution. You have to work very hard to make that convenient. Have a 
look at lftp, for instance. In the end, real GUI programming will be 
easier (and more accessible)

A (still) alternative solution would be an interface to the OS to make 
it a remote mounted folder (works for WebDAV on any modern OS, for 
instance) or a daemon, which watches and synchronizes a directory (this 
is how Dropbox works). This way it feels much more integrated to the 
user - they can use whatever file manager they like to do the transfer, 
or even "save" from any application (like Word, Firefox, ...) into the 
remote folder.

	Christian



From gengyangcai at gmail.com  Sat Nov 28 10:25:10 2015
From: gengyangcai at gmail.com (Cai Gengyang)
Date: Sat, 28 Nov 2015 07:25:10 -0800 (PST)
Subject: An Educational Software Platform written in Python
Message-ID: <88e7805c-700f-4a39-9698-f5c00401a335@googlegroups.com>

So after reading YCombinator's new RFS, I have decided I want to build an educational software platform written in Python (mostly, if not entirely).


Here is the description from YCombinator's RFS :

If we can fix education, we can eventually do everything else on this list.
The first attempts to use technology to fix education have focused on using the Internet to distribute traditional content to a wider audience. This is good, but the Internet is a fundamentally different medium and capable of much more.

Solutions that combine the mass scale of technology with one-on-one in-person interaction are particularly interesting to us.

This may not require a "breakthrough" technology in the classical sense, but at a minimum it will require very new ways of doing things.


What resources would I need to obtain, learn and utilise on order to create this platform? Can I create something like this entirely in Python, or would I need to learn other technologies? Anyone can give some directions, thanks alot !


Gengyang


From lac at openend.se  Sat Nov 28 11:02:31 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 17:02:31 +0100
Subject: askopenfilename()
In-Reply-To: <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de>
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hlr7$d1j$2@net.de> <n2ia83$icf$2@nuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de> <n3c3vu$a8t$1@dont-email.me>
 <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de>
Message-ID: <201511281602.tASG2VgT020533@fido.openend.se>

Maybe Wei Li Jiang's  hack will work for you?
http://stackoverflow.com/questions/3375227/how-to-give-tkinter-file-dialog-focus

But then see if it works under MacOS.  I fear it will not.

Laura


From framstag at rus.uni-stuttgart.de  Sat Nov 28 11:05:57 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Sat, 28 Nov 2015 16:05:57 +0000 (UTC)
Subject: askopenfilename()
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2hkho$d1j$1@news2.informatik.uni-stuttgart.de> <n2hlr7$d1j$2@net.de>
 <n2ia83$icf$2@nuttgart.de> <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3cjd5$pip$1@news2.informatik.uni-stuttgart.de>

Ulli Horlacher <framstag at rus.uni-stuttgart.de> wrote:

> One of my Windows test users reports, that the file dialog window of
> askopenfilename() starts behind the console window and has no focus.

I have got a followup: this happens only with Windows XP, not with Windows
7. Therefore I will ignore this problem :-)


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From rhills at medimorphosis.com.au  Sat Nov 28 11:25:07 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Sun, 29 Nov 2015 00:25:07 +0800
Subject: Find relative url in mixed text/html
In-Reply-To: <8737vqyag1.fsf@jester.gateway.pace.com>
References: <mailman.182.1448678122.20593.python-list@python.org>
 <8737vqyag1.fsf@jester.gateway.pace.com>
Message-ID: <5659D563.6000005@medimorphosis.com.au>

Hi Paul,

On 28/11/15 13:11, Paul Rubin wrote:
> Rob Hills <rhills at medimorphosis.com.au> writes:
>> Note, in the beginning of this project, I looked at using "Beautiful
>> Soup" but my reading and limited testing lead me to believe that it is
>> designed for well-formed HTML/XML and therefore was unsuitable for the
>> text/html soup I have.  If that belief is incorrect, I'd be grateful for
>> general tips about using Beautiful Soup in this scenario...
> Beautiful Soup can deal with badly formed HTML pretty well, or at least
> it could in earlier versions.  It gives you several different parsing
> options to choose from now.  I think the default is lxml which is fast
> but maybe more strict.  Check what the others are and see if a loose
> slow one is still there.  It really is pretty slow so plan on a big
> computation task if you're converting a large forum.

I've had another look at Beautiful Soup and while it doesn't really help
me much with urls (relative or absolute) embedded within text, it seems
to do a good job of separating out links from the rest, so that could be
useful in itself.

WRT time, I'm converting about 65MB of data which currently takes 14
seconds (on a 3yo laptop with a SSD running Ubuntu), which I reckon is
pretty amazing performance for Python3, especially given my relatively
crude coding skills.  It'll be interesting to see if using Beautiful
Soup adds significantly to that.

> phpBB gets a bad rap that's maybe well-deserved but I don't know what to
> suggest instead.

I did start to investigate Python-based alternatives; I've not heard
much good said about php, but I probably move in the wrong circles. 
However, our hosting service doesn't support Python so I stopped
hunting.  Plus there is a significant group of forum members who hold
very strong opinions about the functionality they want and it took a lot
of work to get them to agree on something!

All that said, I'd be interested to see specific (and hopefully
unbiased) info about phpBB's failings...

Cheers,

-- 
Rob Hills
Waikiki, Western Australia



From marko at pacujo.net  Sat Nov 28 11:39:36 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Sat, 28 Nov 2015 18:39:36 +0200
Subject: An Educational Software Platform written in Python
References: <88e7805c-700f-4a39-9698-f5c00401a335@googlegroups.com>
Message-ID: <87r3ja13jr.fsf@elektro.pacujo.net>

Cai Gengyang <gengyangcai at gmail.com>:

> Can I create something like this entirely in Python,

Absolutely. It will only take ten to one hundred years for one person to
create.


Marko


From framstag at rus.uni-stuttgart.de  Sat Nov 28 11:45:51 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Sat, 28 Nov 2015 16:45:51 +0000 (UTC)
Subject: askopenfilename()
References: <n2hdfn$b1d$1@news2.informatik.uni-stuttgart.de>
 <n2ia83$icf$2@news2.informatik.uni-stuttgart.de>
 <mailman.419.1447869376.16136.python-list@python.org>
 <n2kqvn$8de$1@news2.informatik.uni-stuttgart.de> <564DF94E.8020302@gmail.com>
 <mailman.509.1448009036.16136.python-list@python.org>
 <n2vgq3$76g$1@news2.informatik.uni-stuttgart.de>
 <n3bvn3$k2f$1@news2.informatik.uni-stuttgart.de> <n3c3vu$a8t$1@dont-email.me>
 <n3c7rb$m4v$1@news2.informatik.uni-stuttgart.de> <n3cacj$o5$1@dont-email.me>
Message-ID: <n3clnv$pip$2@news2.informatik.uni-stuttgart.de>

Christian Gollwitzer <auriocus at gmx.de> wrote:

> Am 28.11.15 um 13:48 schrieb Ulli Horlacher:
> > Christian Gollwitzer <auriocus at gmx.de> wrote:
> >> Many problems would simply go away if you wrote the whole thing as a GUI
> >> program.
> >
> > Too much hassle.
> > The predecessor was a Perl/Tk program and I have had to invest 90% of the
> > programming work into the GUI handling. No fun at all.
> 
> As I see it, the program consists only of user interface - or is there 
> any "algorithm" working behinds the scenes?

There is a lot of "algorithms", about 50 kB of code:
- resuming upload and download after link failures
- sending multiple files as zip or tar containers
- deleting files
- configuring login
- handling HTTP proxy
- many other things...


> Maybe you could pass the task on to somebody who enjoys GUI programming?

No, I then have to maintain it. I do not like to support foreign code. I
was in this situation already. The client was written in Java, which I do
not know. I have had to throw it away some day, because I was not able to
fix the bugs.

Therefore I started to write the new client fexit in Python.
Here we are :-)


> > This is only one of the tasks. The main menu looks:
> >
> > [s]  send a file or directory
> > [g]  get a file
> > [c]  change login data (user, server, auth-ID)
> > [l]  login with webbrowser
> > [u]  update fexit
> > [h]  help
> > [q]  quit
> 
> All of this is easily integrated into a GUI like the one I posted (have 
> you tried it?)

As I wrote: I have done this already with Perl/Tk and it was HASSLE.
No fun at all.


> IMO the most common GUI pattern for this kind of thing is a side-by-side
> view of the directories on the server and on the client

There is no directory view on server side.


> For an experienced GUI script writer it'll take a weekend to get the
> basics running.

I am not even a beginner GUI script writer and I do not want to become one.
GUIs are most superfluous and delay the work flow.


> for guided user input, an interface which prompts the user for input has
> never been a good solution. You have to work very hard to make that
> convenient. 

This is easy, because they have no alternative :-)


> Have a look at lftp, for instance. 

Yes. Horrible user interface and even more horrible to program :-}


> A (still) alternative solution would be an interface to the OS to make 
> it a remote mounted folder 

There are no remote folders.


> (works for WebDAV on any modern OS, for instance) or a daemon, which
> watches and synchronizes a directory (this is how Dropbox works).

A VERY bad idea, if you have to send TB files.


> This way it feels much more integrated to the user 

It shall not look integrated. The user should think before using it.


> they can use whatever file manager they like to do the transfer

There are no file manager which supports the F*EX protocol.
Therefore I am forced to write my own clients.
I am a lazy guy: if there is already a program, I will happily use it.
Only if there is none, I program it by myself.


> or even "save" from any application (like Word, Firefox, ...) into the
> remote folder.

There are no remote folders.

-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From lac at openend.se  Sat Nov 28 12:04:08 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 18:04:08 +0100
Subject: Find relative url in mixed text/html
In-Reply-To: <5659D563.6000005@medimorphosis.com.au>
References: <mailman.182.1448678122.20593.python-list@python.org>
 <8737vqyag1.fsf@jester.gateway.pace.com>
 <5659D563.6000005@medimorphosis.com.au>
Message-ID: <201511281704.tASH48eB021469@fido.openend.se>

In a message of Sun, 29 Nov 2015 00:25:07 +0800, Rob Hills writes:
>All that said, I'd be interested to see specific (and hopefully
>unbiased) info about phpBB's failings...

People I know of who run different bb software say that the spammers
really prefer phpBB.  So keeping it spam free is about 4 times the
work as for, for instance, IPB.

Hackers seem to like it too -- possibly due to this:
http://defensivedepth.com/2009/03/03/anatomy-of-a-hack-the-phpbbcom-attack/

make sure you aren't vulnerable.



From amfarrell at mit.edu  Sat Nov 28 12:18:05 2015
From: amfarrell at mit.edu (Andrew Farrell)
Date: Sat, 28 Nov 2015 11:18:05 -0600
Subject: An Educational Software Platform written in Python
In-Reply-To: <87r3ja13jr.fsf@elektro.pacujo.net>
References: <88e7805c-700f-4a39-9698-f5c00401a335@googlegroups.com>
 <87r3ja13jr.fsf@elektro.pacujo.net>
Message-ID: <CA+y5TLaZowUg1tJ2fkEBZ-EQWcueYvSv4VEGe3BudLamNDgxYg@mail.gmail.com>

I would look first at the open source software released by EdX:
https://open.edx.org/

On Sat, Nov 28, 2015 at 10:39 AM, Marko Rauhamaa <marko at pacujo.net> wrote:

> Cai Gengyang <gengyangcai at gmail.com>:
>
> > Can I create something like this entirely in Python,
>
> Absolutely. It will only take ten to one hundred years for one person to
> create.
>
>
> Marko
> --
> https://mail.python.org/mailman/listinfo/python-list
>


From rhills at medimorphosis.com.au  Sat Nov 28 12:40:49 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Sun, 29 Nov 2015 01:40:49 +0800
Subject: Find relative url in mixed text/html
In-Reply-To: <201511281704.tASH48eB021469@fido.openend.se>
References: <mailman.182.1448678122.20593.python-list@python.org>
 <8737vqyag1.fsf@jester.gateway.pace.com>
 <5659D563.6000005@medimorphosis.com.au>
 <201511281704.tASH48eB021469@fido.openend.se>
Message-ID: <5659E721.4020007@medimorphosis.com.au>

Hi Laura,

On 29/11/15 01:04, Laura Creighton wrote:
> In a message of Sun, 29 Nov 2015 00:25:07 +0800, Rob Hills writes:
>> All that said, I'd be interested to see specific (and hopefully
>> unbiased) info about phpBB's failings...
> People I know of who run different bb software say that the spammers
> really prefer phpBB.  So keeping it spam free is about 4 times the
> work as for, for instance, IPB.
>
> Hackers seem to like it too -- possibly due to this:
> http://defensivedepth.com/2009/03/03/anatomy-of-a-hack-the-phpbbcom-attack/
>
> make sure you aren't vulnerable.

Thanks for the link and the advice.

Personally, I'd rather go with something based on a language I am
reasonably familiar with (eg Python or Java) however it seems the vast
bulk of Forum software is based on PHP :-(

Cheers,

-- 
Rob Hills
Waikiki, Western Australia



From rhills at medimorphosis.com.au  Sat Nov 28 12:44:58 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Sun, 29 Nov 2015 01:44:58 +0800
Subject: Find relative url in mixed text/html
In-Reply-To: <n3bjmq$pdi$1@dont-email.me>
References: <mailman.182.1448678122.20593.python-list@python.org>
 <n3bjmq$pdi$1@dont-email.me>
Message-ID: <5659E81A.3090202@medimorphosis.com.au>

Hi Grobu,

On 28/11/15 15:07, Grobu wrote:
> Is it safe to assume that all the relative (cross) links take one of
> the following forms? :
>
>     http://www.aeva.asn.au/forums/forum_posts.asp
>     www.aeva.asn.au/forums/forum_posts.asp
>     /forums/forum_posts.asp
>     /forum_posts.asp (are you really sure about this one?)
>
> If so, and if your goal boils down to converting all instances of old
> style URLs to new style ones regardless of the context where they
> appear, why would a regex fail to meet your needs?

I'm actually not discounting anything and as I mentioned, I've already
used some regex to extract the properly-formed URLs (those starting with
http://).  I was fortunately able to find some example regex that I
could figure out enough to tweak for my purpose.  Unfortunately, my
small brain hurts whenever I try and understand what a piece of regex is
doing and I don't like having bits in my code that hurt my brain. 

BTW, that's not meant to be an invitation to someone to produce some
regex for me, if I can't find any other way of doing it, I'll try and
create my own regex and come back here if I can't get that working.

Cheers,

-- 
Rob Hills
Waikiki, Western Australia



From no.email at nospam.invalid  Sat Nov 28 13:10:28 2015
From: no.email at nospam.invalid (Paul Rubin)
Date: Sat, 28 Nov 2015 10:10:28 -0800
Subject: Find relative url in mixed text/html
References: <mailman.182.1448678122.20593.python-list@python.org>
 <8737vqyag1.fsf@jester.gateway.pace.com>
 <5659D563.6000005@medimorphosis.com.au>
 <201511281704.tASH48eB021469@fido.openend.se>
 <mailman.190.1448732454.20593.python-list@python.org>
Message-ID: <87a8pyc7vv.fsf@nightsong.com>

Rob Hills <rhills at medimorphosis.com.au> writes:
> Personally, I'd rather go with something based on a language I am
> reasonably familiar with (eg Python or Java) however it seems the vast
> bulk of Forum software is based on PHP :-(

It's certainly possible to write good software in PHP, so it's mostly
a matter of the design and implementation quality.

I was on a big PhpBB forum years ago and it got very slow as the
database got large, and there were multiple incidents of database
corruption.  The board eventually switched to VBB which was a lot
better.  VBB is the best one I know of but it's not FOSS.

I'm on another one right now which uses IPB (also not FOSS) and don't
like it much (too clever for its own good).

Another one is FluxBB which is nice and lightweight and FOSS, but it's a
small forum and the software might not be up to handling a bigger one.

Some people like Discourse.  I don't like it much myself, but that's
just me.

There's certainly plenty of cheap hosting available these days (or raw
VPS) that let you run Python or whatever else you want.  But it seems to
me that forum software is something of a ghetto.  I do think there is
some written in Python but I don't remember any specifics.


From real-not-anti-spam-address at apple-juice.co.uk  Sat Nov 28 14:37:21 2015
From: real-not-anti-spam-address at apple-juice.co.uk (D.M. Procida)
Date: Sat, 28 Nov 2015 19:37:21 +0000
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
Message-ID: <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>

Jon Ribbens <jon+usenet at unequivocal.co.uk> wrote:

> On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk>
wrote:
> > I have a new installation of Debian Jessie, with Python 2.7 and 3.4
> > installed.
> >
> > I want to use Python 3.4 by default for most things, so I want
> > virtualenv to create Python 3.4 virtualenvs unless I ask it to
> > otherwise.
> >
> > It turns out that this seems to be inordinately complex.
> 
> sudo apt-get remove python-virtualenv
> sudo apt-get install python3-virtualenv

Yup, I did try installing python3-virtualenv, but it didn't appear
actually do do anything. It didn't provide me with a virtualenv command,
that's for sure.

And pages such as https://packages.debian.org/jessie/python3-virtualenv
are not exactly informative.

Is something else required?

Daniele 


From joel.goldstick at gmail.com  Sat Nov 28 16:33:40 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sat, 28 Nov 2015 16:33:40 -0500
Subject: An Educational Software Platform written in Python
In-Reply-To: <87r3ja13jr.fsf@elektro.pacujo.net>
References: <88e7805c-700f-4a39-9698-f5c00401a335@googlegroups.com>
 <87r3ja13jr.fsf@elektro.pacujo.net>
Message-ID: <CAPM-O+wrKROvFDP2mYwSBTkvWbm3ygX5ZphwpXa7kQGiBgwEZg@mail.gmail.com>

On Sat, Nov 28, 2015 at 11:39 AM, Marko Rauhamaa <marko at pacujo.net> wrote:

> Cai Gengyang <gengyangcai at gmail.com>:
>
> > Can I create something like this entirely in Python,
>
> Absolutely. It will only take ten to one hundred years for one person to
> create.
>
>
> Marko
> --
> https://mail.python.org/mailman/listinfo/python-list
>


Cai,

Start small.  write some 10 line programs.  Then some 30 line programs.
 then write 100 more usefull programs.  Then you will understand what it is
you can do or can't.
-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From matthew.herzog at gmail.com  Sat Nov 28 16:45:34 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sat, 28 Nov 2015 13:45:34 -0800 (PST)
Subject: Generate config file from template using Python search and replace.
Message-ID: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>

I need to generate a config file based on an existing "template" file. I need to replace a set of strings with other strings globally in the generated file.

Here is a snippet of the template file, where CONTENT_PATH and DAMPATH are two "placeholders" or variables. There are several other such placeholders.

      $include "_dispatcher_publish_filters.any"
      /1000 { /type "allow"  /glob "* /CONTENT_PATH/*.html*" }
      /1001 { /type "allow"  /glob "POST /DAMPATH/www/*.html *" }

The script's user will be asked to type in unique values when prompted for DAMPATH or CONTENT_PATH.

Since I know the variables themselves are not going to change (because the contents of the template file don't spontaneously change) should I be using regex to search for them or is there a better way? I was planning on using re.sub but I don't know whether that's the best way. Here's what my script looks like today.

from sys import argv
import re
from os.path import exists

script, template_file = argv
print "Opening the template file..."

in_file = open(template_file)
lines = in_file.readlines()

print "What is the serial number of the site?",
_NNN = raw_input()

print "What is the brand, or product name?",
_BRAND = raw_input()

print "What is the content path?",
_CONTENT_PATH = raw_input()

out_file = open(_nnn + _brand + "_farm.any", 'w')

for line in lines:
   re.sub('NNN', _NNN, line)
   re.sub('BRAND, _BRAND', line)
   re.sub('CONTENT_PATH', _CONTENT_PATH, line)

out_file.close()


From jon+usenet at unequivocal.co.uk  Sat Nov 28 16:48:37 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Sat, 28 Nov 2015 21:48:37 -0000 (UTC)
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
Message-ID: <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk> wrote:
> Jon Ribbens <jon+usenet at unequivocal.co.uk> wrote:
>
>> On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk>
> wrote:
>> > I have a new installation of Debian Jessie, with Python 2.7 and 3.4
>> > installed.
>> >
>> > I want to use Python 3.4 by default for most things, so I want
>> > virtualenv to create Python 3.4 virtualenvs unless I ask it to
>> > otherwise.
>> >
>> > It turns out that this seems to be inordinately complex.
>> 
>> sudo apt-get remove python-virtualenv
>> sudo apt-get install python3-virtualenv
>
> Yup, I did try installing python3-virtualenv, but it didn't appear
> actually do do anything. It didn't provide me with a virtualenv command,
> that's for sure.
>
> And pages such as https://packages.debian.org/jessie/python3-virtualenv
> are not exactly informative.
>
> Is something else required?

Hmm. Well basically the answer to your question is that you want
virtualenv to be installed by Python 3, then it will default to using
it. Debian's package management is mysterious and apparently bizarre
and frankly in respect to Python, not very good. So perhaps the best
thing to do is simply ignore it and install virtualenv yourself with:

  sudo apt-get install python3-pip
  sudo pip3 install virtualenv

... although you might want to install pip manually too.


From ryanshuell at gmail.com  Sat Nov 28 17:03:10 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Sat, 28 Nov 2015 14:03:10 -0800 (PST)
Subject: Does Python allow variables to be passed into function for dynamic
 screen scraping?
Message-ID: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>

I'm looking at this URL.
https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names

If I hit F12 I can see tags such as these:
<a title=
<a class=
And so on and so forth.  

I'm wondering if someone can share a script, or a function, that will allow me to pass in variables and download (or simply print) the results.  I saw a sample online that I thought would work, and I made a few modifications but now I keep getting a message that says: ValueError: All objects passed were None

Here's the script that I'm playing around with.

import requests
import pandas as pd
from bs4 import BeautifulSoup

#Get the relevant webpage set the data up for parsing
url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
r = requests.get(url)
soup=BeautifulSoup(r.content,"lxml")

#set up a function to parse the "soup" for each category of information and put it in a DataFrame
def get_match_info(soup,tag,class_name):
    info_array=[]
    for info in soup.find_all('%s'%tag,attrs={'class':'%s'%class_name}):
        return pd.DataFrame(info_array)

#for each category pass the above function the relevant information i.e. tag names
tag1 = get_match_info(soup,"td","title")
tag2 = get_match_info(soup,"td","class")

#Concatenate the DataFrames to present a final table of all the above info 
match_info = pd.concat([tag1,tag2],ignore_index=False,axis=1)

print match_info

I'd greatly appreciate any help with this.



From matthew.herzog at gmail.com  Sat Nov 28 17:04:38 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sat, 28 Nov 2015 14:04:38 -0800 (PST)
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
Message-ID: <8324634d-5afe-48d6-942a-1b006ddc0ce4@googlegroups.com>

I should mention the template file is small, just 98 lines long and the working config file will be the same size.


From lac at openend.se  Sat Nov 28 17:28:25 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 23:28:25 +0100
Subject: Does Python allow variables to be passed into function for
 dynamic screen scraping?
In-Reply-To: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
References: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
Message-ID: <201511282228.tASMSPhf025908@fido.openend.se>

In a message of Sat, 28 Nov 2015 14:03:10 -0800, ryguy7272 writes:
>I'm looking at this URL.
>https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
>
>If I hit F12 I can see tags such as these:
><a title=
><a class=
>And so on and so forth.  
>
>I'm wondering if someone can share a script, or a function, that will allow me to pass in variables and download (or simply print) the results.  I saw a sample online that I thought would work, and I made a few modifications but now I keep getting a message that says: ValueError: All objects passed were None
>
>Here's the script that I'm playing around with.
>
>import requests
>import pandas as pd
>from bs4 import BeautifulSoup
>
>#Get the relevant webpage set the data up for parsing
>url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
>r = requests.get(url)
>soup=BeautifulSoup(r.content,"lxml")
>
>#set up a function to parse the "soup" for each category of information and put it in a DataFrame
>def get_match_info(soup,tag,class_name):
>    info_array=[]
>    for info in soup.find_all('%s'%tag,attrs={'class':'%s'%class_name}):
>        return pd.DataFrame(info_array)
>
>#for each category pass the above function the relevant information i.e. tag names
>tag1 = get_match_info(soup,"td","title")
>tag2 = get_match_info(soup,"td","class")
>
>#Concatenate the DataFrames to present a final table of all the above info 
>match_info = pd.concat([tag1,tag2],ignore_index=False,axis=1)
>
>print match_info
>
>I'd greatly appreciate any help with this.

Post your error traceback.  If you are getting Value Errors about None,
then probably something you expect to return a match, isn't.  But without
the actual error, we cannot help much.

Laura



From ryanshuell at gmail.com  Sat Nov 28 17:37:26 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Sat, 28 Nov 2015 14:37:26 -0800 (PST)
Subject: Does Python allow variables to be passed into function for
 dynamic screen scraping?
In-Reply-To: <mailman.1.1448749716.14615.python-list@python.org>
References: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
 <mailman.1.1448749716.14615.python-list@python.org>
Message-ID: <48f7bb74-93f0-4bf8-b781-e7f4b2daf032@googlegroups.com>

On Saturday, November 28, 2015 at 5:28:55 PM UTC-5, Laura Creighton wrote:
> In a message of Sat, 28 Nov 2015 14:03:10 -0800, ryguy7272 writes:
> >I'm looking at this URL.
> >https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
> >
> >If I hit F12 I can see tags such as these:
> ><a title=
> ><a class=
> >And so on and so forth.  
> >
> >I'm wondering if someone can share a script, or a function, that will allow me to pass in variables and download (or simply print) the results.  I saw a sample online that I thought would work, and I made a few modifications but now I keep getting a message that says: ValueError: All objects passed were None
> >
> >Here's the script that I'm playing around with.
> >
> >import requests
> >import pandas as pd
> >from bs4 import BeautifulSoup
> >
> >#Get the relevant webpage set the data up for parsing
> >url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
> >r = requests.get(url)
> >soup=BeautifulSoup(r.content,"lxml")
> >
> >#set up a function to parse the "soup" for each category of information and put it in a DataFrame
> >def get_match_info(soup,tag,class_name):
> >    info_array=[]
> >    for info in soup.find_all('%s'%tag,attrs={'class':'%s'%class_name}):
> >        return pd.DataFrame(info_array)
> >
> >#for each category pass the above function the relevant information i.e. tag names
> >tag1 = get_match_info(soup,"td","title")
> >tag2 = get_match_info(soup,"td","class")
> >
> >#Concatenate the DataFrames to present a final table of all the above info 
> >match_info = pd.concat([tag1,tag2],ignore_index=False,axis=1)
> >
> >print match_info
> >
> >I'd greatly appreciate any help with this.
> 
> Post your error traceback.  If you are getting Value Errors about None,
> then probably something you expect to return a match, isn't.  But without
> the actual error, we cannot help much.
> 
> Laura


Ok.  How do I post the error traceback?  I'm using Spyder Python 2.7.


From lac at openend.se  Sat Nov 28 17:44:21 2015
From: lac at openend.se (Laura Creighton)
Date: Sat, 28 Nov 2015 23:44:21 +0100
Subject: Does Python allow variables to be passed into function for
 dynamic screen scraping?
In-Reply-To: <48f7bb74-93f0-4bf8-b781-e7f4b2daf032@googlegroups.com>
References: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
 <mailman.1.1448749716.14615.python-list@python.org>
 <48f7bb74-93f0-4bf8-b781-e7f4b2daf032@googlegroups.com>
Message-ID: <201511282244.tASMiLKp026166@fido.openend.se>

In a message of Sat, 28 Nov 2015 14:37:26 -0800, ryguy7272 writes:
>On Saturday, November 28, 2015 at 5:28:55 PM UTC-5, Laura Creighton wrote:
>> In a message of Sat, 28 Nov 2015 14:03:10 -0800, ryguy7272 writes:
>> >I'm looking at this URL.
>> >https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
>> >
>> >If I hit F12 I can see tags such as these:
>> ><a title=
>> ><a class=
>> >And so on and so forth.  
>> >
>> >I'm wondering if someone can share a script, or a function, that will allow me to pass in variables and download (or simply print) the results.  I saw a sample online that I thought would work, and I made a few modifications but now I keep getting a message that says: ValueError: All objects passed were None
>> >
>> >Here's the script that I'm playing around with.
>> >
>> >import requests
>> >import pandas as pd
>> >from bs4 import BeautifulSoup
>> >
>> >#Get the relevant webpage set the data up for parsing
>> >url = "https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names"
>> >r = requests.get(url)
>> >soup=BeautifulSoup(r.content,"lxml")
>> >
>> >#set up a function to parse the "soup" for each category of information and put it in a DataFrame
>> >def get_match_info(soup,tag,class_name):
>> >    info_array=[]
>> >    for info in soup.find_all('%s'%tag,attrs={'class':'%s'%class_name}):
>> >        return pd.DataFrame(info_array)
>> >
>> >#for each category pass the above function the relevant information i.e. tag names
>> >tag1 = get_match_info(soup,"td","title")
>> >tag2 = get_match_info(soup,"td","class")
>> >
>> >#Concatenate the DataFrames to present a final table of all the above info 
>> >match_info = pd.concat([tag1,tag2],ignore_index=False,axis=1)
>> >
>> >print match_info
>> >
>> >I'd greatly appreciate any help with this.
>> 
>> Post your error traceback.  If you are getting Value Errors about None,
>> then probably something you expect to return a match, isn't.  But without
>> the actual error, we cannot help much.
>> 
>> Laura
>
>
>Ok.  How do I post the error traceback?  I'm using Spyder Python 2.7.

You cut and paste it out of wherever you are reading it, and paste it
into the email, along with your code, also cut and pasted from somewhere
(like an editor).  That way we get the exact code that caused the exact
traceback you are getting.

Laura



From __peter__ at web.de  Sat Nov 28 18:07:53 2015
From: __peter__ at web.de (Peter Otten)
Date: Sun, 29 Nov 2015 00:07:53 +0100
Subject: Generate config file from template using Python search and
 replace.
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
Message-ID: <n3dc4a$bli$1@ger.gmane.org>

Mr Zaug wrote:

> I need to generate a config file based on an existing "template" file. I
> need to replace a set of strings with other strings globally in the
> generated file.
> 
> Here is a snippet of the template file, where CONTENT_PATH and DAMPATH are
> two "placeholders" or variables. There are several other such
> placeholders.
> 
>       $include "_dispatcher_publish_filters.any"
>       /1000 { /type "allow"  /glob "* /CONTENT_PATH/*.html*" }
>       /1001 { /type "allow"  /glob "POST /DAMPATH/www/*.html *" }
> 
> The script's user will be asked to type in unique values when prompted for
> DAMPATH or CONTENT_PATH.
> 
> Since I know the variables themselves are not going to change (because the
> contents of the template file don't spontaneously change) should I be
> using regex to search for them or is there a better way? I was planning on
> using re.sub but I don't know whether that's the best way. Here's what my
> script looks like today.
> 
> from sys import argv
> import re
> from os.path import exists
> 
> script, template_file = argv
> print "Opening the template file..."
> 
> in_file = open(template_file)
> lines = in_file.readlines()
> 
> print "What is the serial number of the site?",
> _NNN = raw_input()
> 
> print "What is the brand, or product name?",
> _BRAND = raw_input()
> 
> print "What is the content path?",
> _CONTENT_PATH = raw_input()
> 
> out_file = open(_nnn + _brand + "_farm.any", 'w')
> 
> for line in lines:
>    re.sub('NNN', _NNN, line)
>    re.sub('BRAND, _BRAND', line)
>    re.sub('CONTENT_PATH', _CONTENT_PATH, line)
> 
> out_file.close()

There are many templating systems out there. Pick the one that suits you 
best. A very basic one is str.format():

>>> "{foo} {bar}".format(foo=1, bar=2)
'1 2'

Here's what your script might become if you choose that one:

$ cat interactive_template.txt
      $include "_dispatcher_publish_filters.any"
      /1000 {{ /type "allow"  /glob "* /{CONTENT_PATH}/*.html*" }}
      /1001 {{ /type "allow"  /glob "POST /{DAMPATH}/www/*.html *" }}
$ cat interactive_template.py

try:
    format_map = str.format_map
except AttributeError:  # python 2 compatibility
    import string

    def format_map(text, lookup):
        return string.Formatter().vformat(text, (), lookup)
    input = raw_input


class Lookup(dict):
    def __missing__(self, key):
        self[key] = value = input("{}: ".format(key))
        return value


def main():
    import argparse

    parser = argparse.ArgumentParser()
    parser.add_argument("template_file")
    parser.add_argument("generated_file", nargs="?")
    args = parser.parse_args()

    with open(args.template_file) as instream:
        template_text = instream.read()

    lookup = Lookup()
    generated_text = format_map(template_text, lookup)
    generated_file = args.generated_file
    if generated_file is None:
        generated_file = format_map("{nnn}{brand}_farm.any", lookup)
    print("Writing {}".format(generated_file))
    with open(generated_file, "w") as outstream:
        outstream.write(generated_text)


if __name__ == "__main__":
    main()
$ python interactive_template.py interactive_template.txt
CONTENT_PATH: foo
DAMPATH: bar
nnn: baz
brand: ham
Writing bazham_farm.any
$ cat bazham_farm.any 
      $include "_dispatcher_publish_filters.any"
      /1000 { /type "allow"  /glob "* /foo/*.html*" }
      /1001 { /type "allow"  /glob "POST /bar/www/*.html *" }




From steve at pearwood.info  Sat Nov 28 20:58:42 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Sun, 29 Nov 2015 12:58:42 +1100
Subject: Does Python allow variables to be passed into function for
 dynamic screen scraping?
References: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
Message-ID: <565a5bd5$0$1606$c3e8da3$5496439d@news.astraweb.com>

On Sun, 29 Nov 2015 09:03 am, ryguy7272 wrote:

> I'm looking at this URL.
> https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names

Don't screen-scrape Wikipedia. Just don't. They have an official API for
downloading content, use it. There's even a Python library for downloading
from Wikipedia and other Mediawiki sites:

https://www.mediawiki.org/wiki/Manual:Pywikibot

Wikimedia does a fantastic job, for free, and automated screen-scraping
hurts their ability to provide that service. It is rude and anti-social.
Please don't do it.



-- 
Steven



From jfong at ms4.hinet.net  Sat Nov 28 21:55:10 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Sat, 28 Nov 2015 18:55:10 -0800 (PST)
Subject: python response slow when running external DLL
In-Reply-To: <mailman.184.1448705627.20593.python-list@python.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
 <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>
 <mailman.184.1448705627.20593.python-list@python.org>
Message-ID: <3ec6a016-dae5-4986-b035-c1a8cd4dc3e7@googlegroups.com>

Peter Otten at 2015/11/28 UTC+8 6:14:09PM wrote?
> No, the point of both recipes is that tkinter operations are only ever 
> invoked from the main thread. The main thread has polling code that 
> repeatedly looks if there are results from the helper thread. As far I 
> understand the polling method has the structure
> 
> f():
>    # did we get something back from the other thread?
>    # a queue is used to avoid race conditions
> 
>    # if yes react.
>    # var_status.set() goes here
> 
>    # reschedule f to run again in a few millisecs; 
>    # that's what after() does

Have no idea how the main thread poll on all those events (or it use a queue)?
All I know now is that the main thread(mainloop()?) can be easily blocked by event handlers if the handler didn't run as a separate thread.

> >     .....
> >     .....
> >     #do the rest
> >     var_status.set('Download...')
> >     _thread.start_new_thread(td_download, ())  #must use threading
> > 
> > def td_download():
> >     result = mydll.SayHello()
> >     if result:
> >         var_status.set("Download Fail at %s" % hex(result))
> >         showerror('Romter', 'Download Fail')
> >     else:
> >         var_status.set('Download OK')
> >         showinfo('Romter', 'Download OK')
> 
> As td_download() runs in the other thread the var_status.set() methods are 
> problematic.

No idea what kind of problem it will encounter. Can you explain?

> Another complication that inevitably comes with concurrency: what if the 
> user triggers another download while one download is already running? If you 
> don't keep track of all downloads the message will already switch to 
> "Download OK" while one download is still running.

Hummm...this thought never comes to my mind. After take a quick test I found, you are right, a second "download" was triggered immediately. That's a shock to me. I suppose the same event shouldn't be triggered again, or at least not triggered immediately, before its previous handler was completed. ...I will take a check later on Borland C++ builder to see how it reacts!

Anyway to prevent this happens? if Python didn't take care it for us.


From jfong at ms4.hinet.net  Sat Nov 28 22:04:23 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Sat, 28 Nov 2015 19:04:23 -0800 (PST)
Subject: python response slow when running external DLL
In-Reply-To: <mailman.185.1448707926.20593.python-list@python.org>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
 <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>
 <n3buoh$3r1$1@ger.gmane.org>
 <mailman.185.1448707926.20593.python-list@python.org>
Message-ID: <3ee1f8f1-afaa-4610-a942-f6cdef61995e@googlegroups.com>

Laura Creighton at 2015/11/28 UTC+8 6:52:25PM wrote?
> I never saw the reply that Peter is replying to.
> The threading module constructs a higher level interface on top of the
> low level thread module.  Thus it is the preferred way to go for
> standard Python code -- and even Fredrik's recipe contains the
> line:
> 	import thread # should use the threading module instead!
> 
> Laura
Hi! Laura, 

takes the porting of an old BCB GUI program as an exercise in my learning python, I just quickly grab the required tools (mainly the tkinter) in python to complete this "work" and get a feeling of how python performs on doing this. Most of my knowledge of python comes from Mark Lutz's book "Learning python" and "Programming python". I didn't dive into this language deeply yet. There are topics about "_thread" and "threading" modules in the book and I just pick the lower level one for this because the "threading" is based on the "_thread".

Thanks for your note and link.

--Jach




From ryanshuell at gmail.com  Sat Nov 28 23:52:59 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Sat, 28 Nov 2015 20:52:59 -0800 (PST)
Subject: Does Python allow variables to be passed into function for
 dynamic screen scraping?
In-Reply-To: <565a5bd5$0$1606$c3e8da3$5496439d@news.astraweb.com>
References: <e13afc4b-ac4e-4a75-bca6-1c7be9399cb6@googlegroups.com>
 <565a5bd5$0$1606$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <2e25f82c-1ed6-4c56-836d-8f9a25990ea9@googlegroups.com>

On Saturday, November 28, 2015 at 8:59:04 PM UTC-5, Steven D'Aprano wrote:
> On Sun, 29 Nov 2015 09:03 am, ryguy7272 wrote:
> 
> > I'm looking at this URL.
> > https://en.wikipedia.org/wiki/Wikipedia:Unusual_place_names
> 
> Don't screen-scrape Wikipedia. Just don't. They have an official API for
> downloading content, use it. There's even a Python library for downloading
> from Wikipedia and other Mediawiki sites:
> 
> https://www.mediawiki.org/wiki/Manual:Pywikibot
> 
> Wikimedia does a fantastic job, for free, and automated screen-scraping
> hurts their ability to provide that service. It is rude and anti-social.
> Please don't do it.
> 
> 
> 
> -- 
> Steven

Thanks Steven.  Do you know of a good tutorial for learning about Wikipedia APIs?  I'm not sure where to get started on this topic.  I did some Google searches, but didn't come up with a lot of useful info...not much actually...


From plucena24 at gmail.com  Sun Nov 29 03:14:03 2015
From: plucena24 at gmail.com (Pablo Lucena)
Date: Sun, 29 Nov 2015 03:14:03 -0500
Subject: https://www.python.org/downloads/ offline
Message-ID: <CAB_tDZyWubAdN8H-2J5YXU5L+r4Zeyeenkvgv1Ve2e246D4Oog@mail.gmail.com>

Is anyone else getting 503 errors when accessing the downloads page of
python.org?


-- 
*Pablo Lucena*


From rosuav at gmail.com  Sun Nov 29 04:26:12 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Sun, 29 Nov 2015 20:26:12 +1100
Subject: https://www.python.org/downloads/ offline
In-Reply-To: <CAB_tDZyWubAdN8H-2J5YXU5L+r4Zeyeenkvgv1Ve2e246D4Oog@mail.gmail.com>
References: <CAB_tDZyWubAdN8H-2J5YXU5L+r4Zeyeenkvgv1Ve2e246D4Oog@mail.gmail.com>
Message-ID: <CAPTjJmpyR6vfPyv54fu0zV53YQ5gULSiyBE_hm_=3LXTgaJm+w@mail.gmail.com>

On Sun, Nov 29, 2015 at 7:14 PM, Pablo Lucena <plucena24 at gmail.com> wrote:
> Is anyone else getting 503 errors when accessing the downloads page of
> python.org?
>
>
> --
> *Pablo Lucena*
> --
> https://mail.python.org/mailman/listinfo/python-list

Yes, the whole site seems to be down. Cc'ing the www list, although
someone probably knows already.

ChrisA


From lele at metapensiero.it  Sun Nov 29 07:19:46 2015
From: lele at metapensiero.it (Lele Gaifax)
Date: Sun, 29 Nov 2015 13:19:46 +0100
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
Message-ID: <8737vp0zh9.fsf@metapensiero.it>

Jon Ribbens <jon+usenet at unequivocal.co.uk> writes:

> On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk> wrote:
>>
>> Is something else required?
>
> Debian's package management is mysterious and apparently bizarre
> and frankly in respect to Python, not very good.

I do not agree with you on the quality of Python support on Debian systems,
but I think Daniele is missing the package "pythonX.Y-venv": they install the
needed stuff, and in particular /usr/bin/pyvenv-X-Y.

ciao, lele.
-- 
nickname: Lele Gaifax | Quando vivr? di quello che ho pensato ieri
real: Emanuele Gaifas | comincer? ad aver paura di chi mi copia.
lele at metapensiero.it  |                 -- Fortunato Depero, 1929.



From lac at openend.se  Sun Nov 29 07:27:02 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 29 Nov 2015 13:27:02 +0100
Subject: Python 3 virtualenvs
In-Reply-To: <8737vp0zh9.fsf@metapensiero.it>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
Message-ID: <201511291227.tATCR2on004824@fido.openend.se>

In a message of Sun, 29 Nov 2015 13:19:46 +0100, Lele Gaifax writes:
>Jon Ribbens <jon+usenet at unequivocal.co.uk> writes:
>
>> On 2015-11-28, D.M. Procida <real-not-anti-spam-address at apple-juice.co.uk> wrote:
>>>
>>> Is something else required?
>>
>> Debian's package management is mysterious and apparently bizarre
>> and frankly in respect to Python, not very good.
>
>I do not agree with you on the quality of Python support on Debian systems,
>but I think Daniele is missing the package "pythonX.Y-venv": they install the
>needed stuff, and in particular /usr/bin/pyvenv-X-Y.
>
>ciao, lele.

No, Pyvenv is precisely what Daniele can not use.
The problem is that venv does not come with a big sign saying

ONLY FOR PYTHON 3.x
ABSOLUTELY DOES NOT WORK FOR BUILDING 2.7 VIRTUALENVS
USE virtualenv INSTEAD for Python 2.7

----

which means you can waste a whole lot of time finding this out
the hard way.

Laura


From jon+usenet at unequivocal.co.uk  Sun Nov 29 08:23:19 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Sun, 29 Nov 2015 13:23:19 -0000 (UTC)
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
Message-ID: <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-29, Laura Creighton <lac at openend.se> wrote:
> In a message of Sun, 29 Nov 2015 13:19:46 +0100, Lele Gaifax writes:
>>Jon Ribbens <jon+usenet at unequivocal.co.uk> writes:
> No, Pyvenv is precisely what Daniele can not use.
> The problem is that venv does not come with a big sign saying
>
> ONLY FOR PYTHON 3.x
> ABSOLUTELY DOES NOT WORK FOR BUILDING 2.7 VIRTUALENVS
> USE virtualenv INSTEAD for Python 2.7
>
> ----
>
> which means you can waste a whole lot of time finding this out
> the hard way.

More specifically, "only for Python >= 3.4", because before that
it does not install pip, which makes it fairly useless.

In my experience the best thing to do is ignore pyvenv and ignore
Debian's package management for anything other than installing
the Python interpreter itself. Install pip by hand, then use that
to install virtualenv, then just use those to create virtualenvs
to run your stuff.

I don't know if, in future, pyvenv will be the way to go and
virtualenv will be deprecated, but either way we do not appear
to be there yet.


From stefan_ml at behnel.de  Sun Nov 29 08:26:41 2015
From: stefan_ml at behnel.de (Stefan Behnel)
Date: Sun, 29 Nov 2015 14:26:41 +0100
Subject: Writing SOME class methods in C
In-Reply-To: <CAHVvXxSEN5PYeJ==u=fWKxAkmsZXU8FhsFOFDQd_05T8M5OgBw@mail.gmail.com>
References: <slrnn4obfa.db7.dh@dotcom.mfs32>
 <CAHVvXxSEN5PYeJ==u=fWKxAkmsZXU8FhsFOFDQd_05T8M5OgBw@mail.gmail.com>
Message-ID: <n3eueh$pfd$1@ger.gmane.org>

Oscar Benjamin schrieb am 18.11.2015 um 13:52:
> On 18 November 2015 at 07:50, Daniel Haude wrote:
>>
>> I'm trying to implement some (but not all) methods of a Python class in C.
>> What I've found on the Net is:
>>  - how to implement entire modules in C so that I can import that module and
>>    use the C functions (successfully done it, too).
>>  - how to implement entire classes in C
> 
> I would suggest to use Cython here. You can write your class in Python
> (that will be compiled to C) and then call out to any C code from any
> of its methods.

Or, in fact, do the reverse: Implement the base class in Cython and inherit
from it in a Python class that extends it. That would give you a fast,
native extension type at the base and leaves you with all the freedom to
extend it in Python code or even natively in other Cython code.

I strongly recommend not to resort to writing real C code here (using the
C-API of CPython). It will be slower and will contain more bugs.

Stefan




From vadodsantos at yahoo.com  Sun Nov 29 08:30:20 2015
From: vadodsantos at yahoo.com (Osvaldo Dias dos Santos)
Date: Sun, 29 Nov 2015 14:30:20 +0100
Subject: Caret key quits idle on pt keyboard
Message-ID: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>

Hi,

I can?t enter a caret in regex on a Portuguese keyboard because by pressing it, IDLE quits.
Any help ?

Thanks.
Kind regards,
Osvaldo





From lac at openend.se  Sun Nov 29 09:12:20 2015
From: lac at openend.se (Laura Creighton)
Date: Sun, 29 Nov 2015 15:12:20 +0100
Subject: Python 3 virtualenvs
In-Reply-To: <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
Message-ID: <201511291412.tATECKN8006265@fido.openend.se>

In a message of Sun, 29 Nov 2015 13:23:19 +0000, Jon Ribbens writes:
>I don't know if, in future, pyvenv will be the way to go and
>virtualenv will be deprecated, but either way we do not appear
>to be there yet.

pyenv is going away.  python -m venv is the preferred way to get a venv

https://bugs.python.org/issue25154

Of course if you try it, you may get:

  Error: Command '['<directory>/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1

which turns out to mean:

Your Python isn't configured with ensure-pip!

.....

Right now, I personally don't know why there is a venv at all.  Despite
the similarity of names, it doesn't seem to be about doing what virtualenv
does.  I think it is only meant to be used by people who want to install
packages but not site-wide, but I am not sure about that.  I don't think
there are any plans to give venv the functionality of virtualenv, so
presumably there are people who like it just fine the way it is now.
They must have very different needs than I do.

Laura


From cescus92 at gmail.com  Sun Nov 29 10:05:30 2015
From: cescus92 at gmail.com (cescus92 at gmail.com)
Date: Sun, 29 Nov 2015 07:05:30 -0800 (PST)
Subject: New JSON encoding method proposal for custom objects
Message-ID: <aac1b6e8-e294-4916-9485-ffc031c3aeb3@googlegroups.com>

Hello everyone!

I'm writing here since I've read on the Pyhton's documentation that this is the most common path that a new proposal should follow. I'd be really glad if this proposal could become a PEP if I see a good response from the community or, in the worst case, understand why this proposal is not good enough.

In this day I stumbled upon a very simple task: I had a list of instances of a custom class and I had to convert i into a JSON.

Actually, from what I've discovered, there are 2 ways to get the JSON out of a custom non serializable instance:
- defining a new method ( e.g. to_json() ) inside the class that converts the item manually (quicker)
- a custom encoder/decoder that goes to extend the ones from the json lib (cleander, I think)

Since I thought it was the most cost-effective and I was in hurry, I took the first way that drove me to a "problem": if I wanted to get the JSON out from my list, it obviously would have given me the "non serializable object" error since the json lib didn't know how to transform it into JSON!

I was astonished that Python was requiring me such ugly ways to accomplish this simple task! JSON WebServices are becoming more and more popular and Python _must_ keep the pace of time! And here it is my proposal to make this task easier in the best Pythonic way :)

I propose that every custom class that wants to allow its instances to have a JSON representation could implement a simple method, __json__().

The way how it works it very straightforward: every time json lib is required to convert an object that doesn't know, it looks for the __json__() method to learn how to treat the object. The duty of this method should be to reduce the complexity of an object instance into an elementary data type (int, str, list, dict, etc..).

Often the process to get the JSON out of an object is a one-way need, in this way it would become even simpler to do it in the most flawless way so the programmer should no more care to implement some custom logic to handle quickly these situations.

Let me give you a very small example of what a __json__ method could be like:

class CustomObj():
  def __init__(self, p1, p2):
    self.p1 = p1
    self.p2 = p2

  def __json__(self):
    return {
      'p1': self.p1,
      'p2': self.p2
    }

Once more, the job of __json__ should simply be the one of make our object json-readable :)

What do you think of it? Do you think it's good? If not, why?

Do you have any guidance to make this idea advance?

Do you advice me to write down a preliminary PEP or to make directly a pull request to the Python's source code?

Thank you for you're time!
I'm waiting for your feedback :)
Have a good Sunday!

Francesco


From __peter__ at web.de  Sun Nov 29 10:46:13 2015
From: __peter__ at web.de (Peter Otten)
Date: Sun, 29 Nov 2015 16:46:13 +0100
Subject: New JSON encoding method proposal for custom objects
References: <aac1b6e8-e294-4916-9485-ffc031c3aeb3@googlegroups.com>
Message-ID: <n3f6k4$h5o$1@ger.gmane.org>

cescus92 at gmail.com wrote:

> Hello everyone!
> 
> I'm writing here since I've read on the Pyhton's documentation that this
> is the most common path that a new proposal should follow. I'd be really
> glad if this proposal could become a PEP if I see a good response from the
> community or, in the worst case, understand why this proposal is not good
> enough.
> 
> In this day I stumbled upon a very simple task: I had a list of instances
> of a custom class and I had to convert i into a JSON.
> 
> Actually, from what I've discovered, there are 2 ways to get the JSON out
> of a custom non serializable instance: - defining a new method ( e.g.
> to_json() ) inside the class that converts the item manually (quicker) - a
> custom encoder/decoder that goes to extend the ones from the json lib
> (cleander, I think)
> 
> Since I thought it was the most cost-effective and I was in hurry, I took
> the first way that drove me to a "problem": if I wanted to get the JSON
> out from my list, it obviously would have given me the "non serializable
> object" error since the json lib didn't know how to transform it into
> JSON!
> 
> I was astonished that Python was requiring me such ugly ways to accomplish
> this simple task! JSON WebServices are becoming more and more popular and
> Python _must_ keep the pace of time! And here it is my proposal to make
> this task easier in the best Pythonic way :)
> 
> I propose that every custom class that wants to allow its instances to
> have a JSON representation could implement a simple method, __json__().
> 
> The way how it works it very straightforward: every time json lib is
> required to convert an object that doesn't know, it looks for the
> __json__() method to learn how to treat the object. The duty of this
> method should be to reduce the complexity of an object instance into an
> elementary data type (int, str, list, dict, etc..).
> 
> Often the process to get the JSON out of an object is a one-way need, in
> this way it would become even simpler to do it in the most flawless way so
> the programmer should no more care to implement some custom logic to
> handle quickly these situations.
> 
> Let me give you a very small example of what a __json__ method could be
> like:
> 
> class CustomObj():
>   def __init__(self, p1, p2):
>     self.p1 = p1
>     self.p2 = p2
> 
>   def __json__(self):
>     return {
>       'p1': self.p1,
>       'p2': self.p2
>     }
> 
> Once more, the job of __json__ should simply be the one of make our object
> json-readable :)
> 
> What do you think of it? Do you think it's good? If not, why?

I'm not sure if that is needed often enough so that adding yet another 
__dunder__ method is worthwhile, particularly as the current mechanism 
already makes an implementation of your idea a matter of a few lines:

>>> import json
>>> class Encoder(json.JSONEncoder):
...   def default(self, obj):
...     try: encode = obj.__json__
...     except AttributeError: return super().default(obj)
...     return encode()
... 
>>> class Foo:
...     def __json__(self): return dict(bar=1, baz=2)
... 
>>> json.dumps({1:2, 3:Foo()}, cls=Encoder)
'{"1": 2, "3": {"baz": 2, "bar": 1}}'

Personally I would find it more interesting if there were a unified 
mechanism for json and pickle. At the very least you should come up with a 
decoding mechanism.

> Do you have any guidance to make this idea advance?

Go to python-ideas for a lengthy discussion ;)

> Do you advice me to write down a preliminary PEP or to make directly a
> pull request to the Python's source code?
> 
> Thank you for you're time!
> I'm waiting for your feedback :)
> Have a good Sunday!
> 
> Francesco




From rossmcm at gmail.com  Sun Nov 29 15:08:26 2015
From: rossmcm at gmail.com (rossmcm at gmail.com)
Date: Sun, 29 Nov 2015 12:08:26 -0800 (PST)
Subject: Installing the gcalcli Python app under windows
Message-ID: <0d7cc2ff-075a-48f9-86f8-943d171a3042@googlegroups.com>

gcalcli (https://github.com/insanum/gcalcli) is a Python application that provides a command-line interface to Google calendar.  All of the stuff I can find on installation seems to be written for *nix platforms and there is precious little for windows.  I'm wondering if anyone can provide the steps involved in getting this thing going under Windows.

My setup:
 - Windows 10
 - Python 2.7
 - PyDev Eclipse 

I don't want to clone the repository, I just want to get the source files I need and anything else I need to run this utility from a command prompt.

I downloaded a zip file from the GitHuib site and then ran a command line "setup.py install" and this produced a whole lot of output:

----------------------------------------------------------------------------
C:\Users\Public\Documents\Downloads\Python\gcalcli\gcalcli-master>setup.py install
running install
running bdist_egg
running egg_info
creating gcalcli.egg-info
writing requirements to gcalcli.egg-info\requires.txt
writing gcalcli.egg-info\PKG-INFO
writing top-level names to gcalcli.egg-info\top_level.txt
writing dependency_links to gcalcli.egg-info\dependency_links.txt
writing manifest file 'gcalcli.egg-info\SOURCES.txt'
reading manifest file 'gcalcli.egg-info\SOURCES.txt'
writing manifest file 'gcalcli.egg-info\SOURCES.txt'
installing library code to build\bdist.win32\egg
running install_lib
warning: install_lib: 'build\lib' does not exist -- no Python modules to install

creating build
creating build\bdist.win32
creating build\bdist.win32\egg
creating build\bdist.win32\egg\EGG-INFO
installing scripts to build\bdist.win32\egg\EGG-INFO\scripts
running install_scripts
running build_scripts
creating build\scripts-2.7
copying and adjusting gcalcli -> build\scripts-2.7
creating build\bdist.win32\egg\EGG-INFO\scripts
copying build\scripts-2.7\gcalcli -> build\bdist.win32\egg\EGG-INFO\scripts
copying gcalcli.egg-info\PKG-INFO -> build\bdist.win32\egg\EGG-INFO
copying gcalcli.egg-info\SOURCES.txt -> build\bdist.win32\egg\EGG-INFO
copying gcalcli.egg-info\dependency_links.txt -> build\bdist.win32\egg\EGG-INFO
copying gcalcli.egg-info\requires.txt -> build\bdist.win32\egg\EGG-INFO
copying gcalcli.egg-info\top_level.txt -> build\bdist.win32\egg\EGG-INFO
zip_safe flag not set; analyzing archive contents...
creating dist
creating 'dist\gcalcli-3.3.2-py2.7.egg' and adding 'build\bdist.win32\egg' to it
removing 'build\bdist.win32\egg' (and everything under it)
Processing gcalcli-3.3.2-py2.7.egg
Copying gcalcli-3.3.2-py2.7.egg to c:\python27\lib\site-packages
Adding gcalcli 3.3.2 to easy-install.pth file
Installing gcalcli script to C:\Python27\Scripts

Installed c:\python27\lib\site-packages\gcalcli-3.3.2-py2.7.egg
Processing dependencies for gcalcli==3.3.2
Searching for oauth2client<=1.4.12
Reading https://pypi.python.org/simple/oauth2client/
Reading http://code.google.com/p/google-api-python-client/
Reading http://github.com/google/oauth2client/
Best match: oauth2client 1.4.12
Downloading https://pypi.python.org/packages/2.7/o/oauth2client/oauth2client-1.4.12-py2.7.egg#md5=8265f6985905a5590c622741980a47e5
Processing oauth2client-1.4.12-py2.7.egg
Moving oauth2client-1.4.12-py2.7.egg to c:\python27\lib\site-packages
Adding oauth2client 1.4.12 to easy-install.pth file

Installed c:\python27\lib\site-packages\oauth2client-1.4.12-py2.7.egg
Searching for google-api-python-client
Best match: google-api-python-client 1.2
Downloading http://google-api-python-client.googlecode.com/files/google-api-python-client-1.2.zip
Processing google-api-python-client-1.2.zip
Writing c:\users\ross\appdata\local\temp\easy_install-a2jaif\google-api-python-client-1.2\setup.cfg
Running google-api-python-client-1.2\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-a2jaif\google-api-python-client-1.2\egg-dist-tmp-uumuki
warning: no files found matching '*.json' under directory 'apiclient'
zip_safe flag not set; analyzing archive contents...
Moving google_api_python_client-1.2-py2.7.egg to c:\python27\lib\site-packages
Adding google-api-python-client 1.2 to easy-install.pth file

Installed c:\python27\lib\site-packages\google_api_python_client-1.2-py2.7.egg
Searching for httplib2
Reading https://pypi.python.org/simple/httplib2/
Reading http://code.google.com/p/httplib2/
Reading https://github.com/jcgregorio/httplib2
Best match: httplib2 0.9.2
Downloading https://pypi.python.org/packages/source/h/httplib2/httplib2-0.9.2.zip#md5=404bac4a4e0d10b3ba498ce483c8c456
Processing httplib2-0.9.2.zip
Writing c:\users\ross\appdata\local\temp\easy_install-jps_ft\httplib2-0.9.2\setup.cfg
Running httplib2-0.9.2\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-jps_ft\httplib2-0.9.2\egg-dist-tmp-cpfwpj
zip_safe flag not set; analyzing archive contents...
httplib2.__init__: module references __file__
creating c:\python27\lib\site-packages\httplib2-0.9.2-py2.7.egg
Extracting httplib2-0.9.2-py2.7.egg to c:\python27\lib\site-packages
Adding httplib2 0.9.2 to easy-install.pth file

Installed c:\python27\lib\site-packages\httplib2-0.9.2-py2.7.egg
Searching for python-gflags
Reading https://pypi.python.org/simple/python-gflags/
Reading http://code.google.com/p/python-gflags
Best match: python-gflags 2.0
Downloading https://pypi.python.org/packages/source/p/python-gflags/python-gflags-2.0.tar.gz#md5=23c9a793959a54971b1f094b0c6d03b1
Processing python-gflags-2.0.tar.gz
Writing c:\users\ross\appdata\local\temp\easy_install-n_jqlw\python-gflags-2.0\setup.cfg
Running python-gflags-2.0\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-n_jqlw\python-gflags-2.0\egg-dist-tmp-0xznni
zip_safe flag not set; analyzing archive contents...
Moving python_gflags-2.0-py2.7.egg to c:\python27\lib\site-packages
Adding python-gflags 2.0 to easy-install.pth file

Installed c:\python27\lib\site-packages\python_gflags-2.0-py2.7.egg
Searching for python-dateutil
Reading https://pypi.python.org/simple/python-dateutil/
Reading http://labix.org/python-dateutil
Reading https://dateutil.readthedocs.org
Best match: python-dateutil 2.4.2
Downloading https://pypi.python.org/packages/source/p/python-dateutil/python-dateutil-2.4.2.tar.gz#md5=4ef68e1c485b09e9f034e10473e5add2
Processing python-dateutil-2.4.2.tar.gz
Writing c:\users\ross\appdata\local\temp\easy_install-5nw3ie\python-dateutil-2.4.2\setup.cfg
Running python-dateutil-2.4.2\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-5nw3ie\python-dateutil-2.4.2\egg-dist-tmp-80gzmb
Moving python_dateutil-2.4.2-py2.7.egg to c:\python27\lib\site-packages
Adding python-dateutil 2.4.2 to easy-install.pth file

Installed c:\python27\lib\site-packages\python_dateutil-2.4.2-py2.7.egg
Searching for six>=1.6.1
Reading https://pypi.python.org/simple/six/
Best match: six 1.10.0
Downloading https://pypi.python.org/packages/source/s/six/six-1.10.0.tar.gz#md5=34eed507548117b2ab523ab14b2f8b55
Processing six-1.10.0.tar.gz
Writing c:\users\ross\appdata\local\temp\easy_install-v1g4z3\six-1.10.0\setup.cfg
Running six-1.10.0\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-v1g4z3\six-1.10.0\egg-dist-tmp-_zal4h
no previously-included directories found matching 'documentation\_build'
zip_safe flag not set; analyzing archive contents...
six: module references __path__
creating c:\python27\lib\site-packages\six-1.10.0-py2.7.egg
Extracting six-1.10.0-py2.7.egg to c:\python27\lib\site-packages
Adding six 1.10.0 to easy-install.pth file

Installed c:\python27\lib\site-packages\six-1.10.0-py2.7.egg
Searching for rsa>=3.1.4
Reading https://pypi.python.org/simple/rsa/
Best match: rsa 3.2.3
Downloading https://pypi.python.org/packages/source/r/rsa/rsa-3.2.3.tar.gz#md5=0e93ca942184650116d84452d4b90253
Processing rsa-3.2.3.tar.gz
Writing c:\users\ross\appdata\local\temp\easy_install-ewgfp0\rsa-3.2.3\setup.cfg
Running rsa-3.2.3\setup.py -q bdist_egg --dist-dir c:\users\ross\appdata\local\temp\easy_install-ewgfp0\rsa-3.2.3\egg-dist-tmp-xaruhh
warning: no files found matching 'README'
zip_safe flag not set; analyzing archive contents...
Moving rsa-3.2.3-py2.7.egg to c:\python27\lib\site-packages
Adding rsa 3.2.3 to easy-install.pth file
Installing pyrsa-encrypt-bigfile-script.py script to C:\Python27\Scripts
Installing pyrsa-encrypt-bigfile.exe script to C:\Python27\Scripts
Installing pyrsa-encrypt-bigfile.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-encrypt-script.py script to C:\Python27\Scripts
Installing pyrsa-encrypt.exe script to C:\Python27\Scripts
Installing pyrsa-encrypt.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-verify-script.py script to C:\Python27\Scripts
Installing pyrsa-verify.exe script to C:\Python27\Scripts
Installing pyrsa-verify.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-sign-script.py script to C:\Python27\Scripts
Installing pyrsa-sign.exe script to C:\Python27\Scripts
Installing pyrsa-sign.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-priv2pub-script.py script to C:\Python27\Scripts
Installing pyrsa-priv2pub.exe script to C:\Python27\Scripts
Installing pyrsa-priv2pub.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-decrypt-script.py script to C:\Python27\Scripts
Installing pyrsa-decrypt.exe script to C:\Python27\Scripts
Installing pyrsa-decrypt.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-decrypt-bigfile-script.py script to C:\Python27\Scripts
Installing pyrsa-decrypt-bigfile.exe script to C:\Python27\Scripts
Installing pyrsa-decrypt-bigfile.exe.manifest script to C:\Python27\Scripts
Installing pyrsa-keygen-script.py script to C:\Python27\Scripts
Installing pyrsa-keygen.exe script to C:\Python27\Scripts
Installing pyrsa-keygen.exe.manifest script to C:\Python27\Scripts

Installed c:\python27\lib\site-packages\rsa-3.2.3-py2.7.egg
Searching for pyasn1-modules>=0.0.5
Reading https://pypi.python.org/simple/pyasn1_modules/
Best match: pyasn1-modules 0.0.8
Downloading https://pypi.python.org/packages/2.7/p/pyasn1-modules/pyasn1_modules-0.0.8-py2.7.egg#md5=f03fff5bc43106475a64a1c34d4052d7
Processing pyasn1_modules-0.0.8-py2.7.egg
Moving pyasn1_modules-0.0.8-py2.7.egg to c:\python27\lib\site-packages
Adding pyasn1-modules 0.0.8 to easy-install.pth file

Installed c:\python27\lib\site-packages\pyasn1_modules-0.0.8-py2.7.egg
Searching for pyasn1>=0.1.7
Reading https://pypi.python.org/simple/pyasn1/
Best match: pyasn1 0.1.9
Downloading https://pypi.python.org/packages/2.7/p/pyasn1/pyasn1-0.1.9-py2.7.egg#md5=08eef0e822233609f6cad55b419ae00c
Processing pyasn1-0.1.9-py2.7.egg
Moving pyasn1-0.1.9-py2.7.egg to c:\python27\lib\site-packages
Adding pyasn1 0.1.9 to easy-install.pth file

Installed c:\python27\lib\site-packages\pyasn1-0.1.9-py2.7.egg
Finished processing dependencies for gcalcli==3.3.2
----------------------------------------------------------------------------

but at the end of this I'm not sure what has happened - it has found my Python installation and copied a whole bunch of stuff there, but there seems to be no trace of a file gcalcli.py on my machine, which is what I was expecting to be created.

Any comments appreciated!



From matthew.herzog at gmail.com  Sun Nov 29 15:23:12 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 12:23:12 -0800 (PST)
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <mailman.3.1448752087.14615.python-list@python.org>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
Message-ID: <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>

When I run this script on OS X El Capitan, I see,
  
  # permission sensitive cache
  $include "_dispatcher_shared_auth-checker: 

Was I supposed to incorporate it into the script I posted?


From denismfmcmahon at gmail.com  Sun Nov 29 15:40:31 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Sun, 29 Nov 2015 20:40:31 -0000 (UTC)
Subject: New JSON encoding method proposal for custom objects
References: <aac1b6e8-e294-4916-9485-ffc031c3aeb3@googlegroups.com>
Message-ID: <n3fnru$5sf$3@dont-email.me>

On Sun, 29 Nov 2015 07:05:30 -0800, cescus92 wrote:

> In this day I stumbled upon a very simple task: I had a list of
> instances of a custom class and I had to convert i into a JSON.

That's all well and good, but firstly you need to both dumps and loads to 
work properly with json, and secondly there's no mechanism in json that 
tells you what class of object you have.

So you may have a __json_dumps__ that will dump your object out to a json 
string representation, but then how does json.loads recognise that it's 
loading your object to call your object's __json_loads__?

-- 
Denis McMahon, denismfmcmahon at gmail.com


From matthew.herzog at gmail.com  Sun Nov 29 16:36:57 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 13:36:57 -0800 (PST)
Subject: I can't understand re.sub
Message-ID: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>

I need to use re.sub to replace strings in a text file. I can't seem to understand how to use the re module to this end.

result = re.sub(pattern, repl, string, count=0, flags=0);

I think I understand that pattern is the regex I'm searching for and repl is the thing I want to substitute for whatever pattern finds but what is string?

The items I'm searching for are few and they do not change. They are "CONTENT_PATH", "ENV" and "NNN". These appear on a few lines in a template file. They do not appear together on any line and they only appear once on each line.

This should be simple, right?


From rxjwg98 at gmail.com  Sun Nov 29 16:36:58 2015
From: rxjwg98 at gmail.com (fl)
Date: Sun, 29 Nov 2015 13:36:58 -0800 (PST)
Subject: What use is this class?
Message-ID: <783981e2-a996-42f9-ad90-8e90a3bd6492@googlegroups.com>

Hi,

When I search around tutorial about None, I came across this link:

http://jaredgrubb.blogspot.ca/2009/04/python-is-none-vs-none.html

I don't understand what use of this class example:



>>> class Zero(): # a class that is zero
...    def __nonzero__(self):
...       return False


I can only get the following code running:

cz1=Zero()
cz1.__nonzero__()
Out[119]: False


Here are my questions:
1. Is there any other means to use class Zero?
2. What connection to None on the original author's intention?


Thanks,


From python at lucidity.plus.com  Sun Nov 29 16:53:51 2015
From: python at lucidity.plus.com (Erik)
Date: Sun, 29 Nov 2015 21:53:51 +0000
Subject: I can't understand re.sub
In-Reply-To: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
Message-ID: <565B73EF.9080708@lucidity.plus.com>

On 29/11/15 21:36, Mr Zaug wrote:
> I need to use re.sub to replace strings in a text file.

Do you? Is there any other way?

> result = re.sub(pattern, repl, string, count=0, flags=0);
>
> I think I understand that pattern is the regex I'm searching for and
> repl is the thing I want to substitute for whatever pattern finds but
> what is string?

Where do you think the function gets the string you want to transform from?

> This should be simple, right?

It is. And it could be even simpler if you don't bother with regexes at 
all (if your input is as fixed as you say it is):

 >>> foo = "foo bar baz spam CONTENT_PATH bar spam"
 >>> ' Substitute '.join(foo.split(' CONTENT_PATH ', 1))
'foo bar baz spam Substitute bar spam'
 >>>

E.


From denismfmcmahon at gmail.com  Sun Nov 29 17:01:34 2015
From: denismfmcmahon at gmail.com (Denis McMahon)
Date: Sun, 29 Nov 2015 22:01:34 -0000 (UTC)
Subject: I can't understand re.sub
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
Message-ID: <n3fsju$348$2@dont-email.me>

On Sun, 29 Nov 2015 13:36:57 -0800, Mr Zaug wrote:

> result = re.sub(pattern, repl, string, count=0, flags=0);

re.sub works on a string, not on a file.

Read the file to a string, pass it in as the string.

Or pre-compile the search pattern(s) and process the file line by line:

import re

patts = [
 (re.compile("axe"), "hammer"),
 (re.compile("cat"), "dog"),
 (re.compile("tree"), "fence")
 ]

with open("input.txt","r") as inf, open("output.txt","w") as ouf:
    line = inf.readline()
    for patt in patts:
        line = patt[0].sub(patt[1], line)
    ouf.write(line)

Not tested, but I think it should do the trick.

Or use a single patt and a replacement func:

import re

patt = re.compile("(axe)|(cat)|(tree)")

def replfunc(match):
    if match == 'axe':
        return 'hammer'
    if match == 'cat':
        return 'dog'
    if match == 'tree':
        return 'fence'
    return match

with open("input.txt","r") as inf, open("output.txt","w") as ouf:
    line = inf.readline()
    line = patt.sub(replfunc, line)
    ouf.write(line)

(also not tested)

-- 
Denis McMahon, denismfmcmahon at gmail.com


From __peter__ at web.de  Sun Nov 29 17:50:17 2015
From: __peter__ at web.de (Peter Otten)
Date: Sun, 29 Nov 2015 23:50:17 +0100
Subject: Generate config file from template using Python search and
 replace.
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
Message-ID: <n3fvf8$pnn$1@ger.gmane.org>

Mr Zaug wrote:

> When I run this script on OS X El Capitan, I see,
>   
>   # permission sensitive cache
>   $include "_dispatcher_shared_auth-checker:
> 
> Was I supposed to incorporate it into the script I posted?

Are you referring to my post? I'm sorry, I can't make sense of your 
question.



From lac at openend.se  Sun Nov 29 19:00:08 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 30 Nov 2015 01:00:08 +0100
Subject: What use is this class?
In-Reply-To: <783981e2-a996-42f9-ad90-8e90a3bd6492@googlegroups.com>
References: <783981e2-a996-42f9-ad90-8e90a3bd6492@googlegroups.com>
Message-ID: <201511300000.tAU008b9013896@fido.openend.se>

In a message of Sun, 29 Nov 2015 13:36:58 -0800, fl writes:
>Hi,
>
>When I search around tutorial about None, I came across this link:
>
>http://jaredgrubb.blogspot.ca/2009/04/python-is-none-vs-none.html
>
>I don't understand what use of this class example:
>
>
>
>>>> class Zero(): # a class that is zero
>...    def __nonzero__(self):
>...       return False
>
>
>I can only get the following code running:
>
>cz1=Zero()
>cz1.__nonzero__()
>Out[119]: False
>
>
>Here are my questions:
>1. Is there any other means to use class Zero?
>2. What connection to None on the original author's intention?

The person who wrote this was curious as to why PEP 8 says:
"Comparisons to singletons like None should always be done 
 with 'is' or 'is not', never the equality operators."

He wrote this class to play around with, to see if it really made
a difference whether you write:

if x is None:

vs

if x == None:

and it does.  A class is free to implement its own version of '==' if
if likes, and there, 'being equal to None' might means something
complicated and crazy.  People who are just testing against None will
burn their fingers if they use '==' there.

Also its a bad problem when porting code to Jython.
A java null is supposed to be None.
But using '==' will call the underlying .equals method.
If you call that on a null, Java will spit out a Null Pointer Exception.

Laura



From ryanshuell at gmail.com  Sun Nov 29 19:49:16 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Sun, 29 Nov 2015 16:49:16 -0800 (PST)
Subject: How can I count word frequency in a web site?
Message-ID: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>

I'm trying to figure out how to count words in a web site.  Here is a sample of the link I want to scrape data from and count specific words.
http://finance.yahoo.com/q/h?s=STRP+Headlines

I only want to count certain words, like 'fraud', 'lawsuit', etc.  I want to have a way to control for specific words.  I have a couple Python scripts that do this for a text file, but not for a web site.  I can post that, if that's helpful.



From rantingrickjohnson at gmail.com  Sun Nov 29 20:12:04 2015
From: rantingrickjohnson at gmail.com (Rick Johnson)
Date: Sun, 29 Nov 2015 17:12:04 -0800 (PST)
Subject: I can't understand re.sub
In-Reply-To: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
Message-ID: <feee81b6-2549-4bfa-b741-35da861a0317@googlegroups.com>

On Sunday, November 29, 2015 at 3:37:34 PM UTC-6, Mr Zaug wrote:

> The items I'm searching for are few and they do not change. They are "CONTENT_PATH", "ENV" and "NNN". These appear on a few lines in a template file. They do not appear together on any line and they only appear once on each line. This should be simple, right?

Yes. In fact so simple that string methods and a "for loop" will suffice. Using regexps for this tasks would be like using a dump truck to haul a teaspoon of salt.



From matthew.herzog at gmail.com  Sun Nov 29 20:20:31 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 17:20:31 -0800 (PST)
Subject: I can't understand re.sub
In-Reply-To: <n3fsju$348$2@dont-email.me>
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
 <n3fsju$348$2@dont-email.me>
Message-ID: <58af2723-cd82-4ce5-a6fd-fbe31d4bf692@googlegroups.com>

Thanks. That does help quite a lot.


From matthew.herzog at gmail.com  Sun Nov 29 20:24:34 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 17:24:34 -0800 (PST)
Subject: I can't understand re.sub
In-Reply-To: <feee81b6-2549-4bfa-b741-35da861a0317@googlegroups.com>
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
 <feee81b6-2549-4bfa-b741-35da861a0317@googlegroups.com>
Message-ID: <967ecfa3-b240-44d6-9a75-bbd9f3865da4@googlegroups.com>

On Sunday, November 29, 2015 at 8:12:25 PM UTC-5, Rick Johnson wrote:
> On Sunday, November 29, 2015 at 3:37:34 PM UTC-6, Mr Zaug wrote:
> 
> > The items I'm searching for are few and they do not change. They are "CONTENT_PATH", "ENV" and "NNN". These appear on a few lines in a template file. They do not appear together on any line and they only appear once on each line. This should be simple, right?
> 
> Yes. In fact so simple that string methods and a "for loop" will suffice. Using regexps for this tasks would be like using a dump truck to haul a teaspoon of salt.

I rarely get a chance to do any scripting so yeah, I stink at it.

Ideally I would have a script that will spit out a config file such as 087_pre-prod_snakeoil_farm.any and not need to manually rename said output file.


From matthew.herzog at gmail.com  Sun Nov 29 20:28:14 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 17:28:14 -0800 (PST)
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <mailman.11.1448837430.14615.python-list@python.org>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
Message-ID: <0dd0db34-7f8f-4e8b-ad6a-c82ad19c2e5e@googlegroups.com>

On Sunday, November 29, 2015 at 5:50:51 PM UTC-5, Peter Otten wrote:
> Mr Zaug wrote:
> 
> > When I run this script on OS X El Capitan, I see,
> >   
> >   # permission sensitive cache
> >   $include "_dispatcher_shared_auth-checker:
> > 
> > Was I supposed to incorporate it into the script I posted?
> 
> Are you referring to my post? I'm sorry, I can't make sense of your 
> question.

Yes. The snippet you posted went way over my head. When I ran it, it printed 

# permission sensitive cache 
  $include "_dispatcher_shared_auth-checker: 


From rxjwg98 at gmail.com  Sun Nov 29 21:06:38 2015
From: rxjwg98 at gmail.com (fl)
Date: Sun, 29 Nov 2015 18:06:38 -0800 (PST)
Subject: variable vs. object
Message-ID: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>

Hi,

I read several parts on line about Python that everything in Python is an 
object. Yes, it is a key difference with other languages. Then, I read a page
it says variables: global and local variable at:

http://www.tutorialspoint.com/python/python_functions.htm


I have a question that whether variables are objects?

For example,

a=10

'a' is an integer. Is it an object too?

Thanks,


From joel.goldstick at gmail.com  Sun Nov 29 21:16:04 2015
From: joel.goldstick at gmail.com (Joel Goldstick)
Date: Sun, 29 Nov 2015 21:16:04 -0500
Subject: variable vs. object
In-Reply-To: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <CAPM-O+zb_c-7Fz9R8P3zYRgOthsWZQOLd675cTbORu_VRLCj+A@mail.gmail.com>

On Sun, Nov 29, 2015 at 9:06 PM, fl <rxjwg98 at gmail.com> wrote:

> Hi,
>
> I read several parts on line about Python that everything in Python is an
> object. Yes, it is a key difference with other languages. Then, I read a
> page
> it says variables: global and local variable at:
>
> http://www.tutorialspoint.com/python/python_functions.htm
>
>
> I have a question that whether variables are objects?
>
> For example,
>
> a=10
>
> 'a' is an integer. Is it an object too?
>

yes

>
> Thanks,
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Joel Goldstick
http://joelgoldstick.com/stats/birthdays


From andre.roberge at gmail.com  Sun Nov 29 21:24:21 2015
From: andre.roberge at gmail.com (=?ISO-8859-1?Q?Andr=E9_Roberge?=)
Date: Sun, 29 Nov 2015 18:24:21 -0800 (PST)
Subject: variable vs. object
In-Reply-To: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <2c516888-de4f-4dd7-b1c0-fe56bb03f754@googlegroups.com>

On Sunday, 29 November 2015 22:06:58 UTC-4, fl  wrote:
> Hi,
> 
> I read several parts on line about Python that everything in Python is an 
> object. Yes, it is a key difference with other languages. Then, I read a page
> it says variables: global and local variable at:
> 
> http://www.tutorialspoint.com/python/python_functions.htm
> 
> 
> I have a question that whether variables are objects?
> 
> For example,
> 
> a=10
> 
> 'a' is an integer. Is it an object too?
> 
> Thanks,

In Python, a "variable" is a name given to an object.  In Python, the "=" sign is used to assign a name to an object: the name is on the left-hand side, and the object is on the right hand side.   Multiple names can be assigned to the same object.  In the example you gave, "a" is a name given to the object "10" which is an integer.    

If you do:

a = 10
b = a
a = "hello"

b will be 10.  b was just another name given to object 10 to which the name "a" was referring to at that point, even though we decided later that a should refer to the string "hello" (which is an object).

Andr?


From matthew.herzog at gmail.com  Sun Nov 29 21:31:28 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Sun, 29 Nov 2015 18:31:28 -0800 (PST)
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <mailman.11.1448837430.14615.python-list@python.org>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
Message-ID: <11d4423f-7912-426c-9d20-d2cb5efba18b@googlegroups.com>

On Sunday, November 29, 2015 at 5:50:51 PM UTC-5, Peter Otten wrote:
> Mr Zaug wrote:
> 
> > When I run this script on OS X El Capitan, I see,
> >   
> >   # permission sensitive cache
> >   $include "_dispatcher_shared_auth-checker:
> > 
> > Was I supposed to incorporate it into the script I posted?
> 
> Are you referring to my post? I'm sorry, I can't make sense of your 
> question.

I seem to be heading in this direction.

#!/usr/bin/env python
import re
from os.path import exists

script, template_file = argv
print "Opening the template file..."

with open (template_file, "r") as a_string:
    data=a_string.read().replace('BRAND', 'Fluxotine')
print(data)

So now the challenge is to use the read().replace magic for multiple values.


From cfkaran2 at gmail.com  Sun Nov 29 21:31:49 2015
From: cfkaran2 at gmail.com (Cem Karan)
Date: Sun, 29 Nov 2015 21:31:49 -0500
Subject: How can I count word frequency in a web site?
In-Reply-To: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
Message-ID: <AE33E0E3-35FA-4C1B-A708-BFD2F83A55D2@gmail.com>

You might want to look into Beautiful Soup (https://pypi.python.org/pypi/beautifulsoup4), which is an HTML screen-scraping tool.  I've never used it, but I've heard good things about it.

Good luck,
Cem Karan

On Nov 29, 2015, at 7:49 PM, ryguy7272 <ryanshuell at gmail.com> wrote:

> I'm trying to figure out how to count words in a web site.  Here is a sample of the link I want to scrape data from and count specific words.
> http://finance.yahoo.com/q/h?s=STRP+Headlines
> 
> I only want to count certain words, like 'fraud', 'lawsuit', etc.  I want to have a way to control for specific words.  I have a couple Python scripts that do this for a text file, but not for a web site.  I can post that, if that's helpful.
> 
> -- 
> https://mail.python.org/mailman/listinfo/python-list



From rhills at medimorphosis.com.au  Sun Nov 29 21:40:29 2015
From: rhills at medimorphosis.com.au (Rob Hills)
Date: Mon, 30 Nov 2015 10:40:29 +0800
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <11d4423f-7912-426c-9d20-d2cb5efba18b@googlegroups.com>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
 <11d4423f-7912-426c-9d20-d2cb5efba18b@googlegroups.com>
Message-ID: <565BB71D.1010303@medimorphosis.com.au>

A program I am writing at present does exactly this and I simply do
multiple calls to string.replace (see below)

On 30/11/15 10:31, Mr Zaug wrote:
> I seem to be heading in this direction.
>
> #!/usr/bin/env python
> import re
> from os.path import exists
>
> script, template_file = argv
> print "Opening the template file..."
>
> with open (template_file, "r") as a_string:
>     data=a_string.read().replace('BRAND', 'Fluxotine')

        data=data.replace('STRING_2', 'New String 2')
        data=data.replace('STRING_3', 'New String 3')

> print(data)
>
> So now the challenge is to use the read().replace magic for multiple values.

It's crude, but it works well for me!

-- 
Rob Hills
Waikiki, Western Australia



From ben+python at benfinney.id.au  Sun Nov 29 21:41:42 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 30 Nov 2015 13:41:42 +1100
Subject: variable vs. object
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <85a8pw8azd.fsf@benfinney.id.au>

fl <rxjwg98 at gmail.com> writes:

> I read several parts on line about Python that everything in Python is an 
> object.

Yes, every piece of information that you can get to with your program,
is made available as an object.

The phrase ?everything is an object? is significant when newcomers are
surprised that, for example, every function is an object; every type is
an object; every number is an object.

> Then, I read a page it says variables [?] I have a question that
> whether variables are objects?

A ?variable?, as we use the term in Python, is a *way to access* a
specific object. It is a binding between a name and an object.

> For example,
>
> a=10
>
> 'a' is an integer. Is it an object too?

More specifically, ?a? is a name. That name is, at any point in time,
bound to some object. The object to which that name is bound is, in your
example, the integer ?10?.

A variable is a specific kind of binding: a binding between one name and
one object. An assignment statement (?a = 10? in your example) binds a
reference to an object. If that reference is a name, then we call that a
?variable?.

The object is not a variable; objects typically do not know whether any
names are bound to them.

The binding from a name to an object is often called a variable.

Everyone serious about Python should watch Ned Batchelder's presentation
on names and values <URL:http://nedbatchelder.com/text/names.html>,
which covers this territory well.

-- 
 \       ?I went to a general store. They wouldn't let me buy anything |
  `\                                     specifically.? ?Steven Wright |
_o__)                                                                  |
Ben Finney



From ben+python at benfinney.id.au  Sun Nov 29 21:45:55 2015
From: ben+python at benfinney.id.au (Ben Finney)
Date: Mon, 30 Nov 2015 13:45:55 +1100
Subject: variable vs. object
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
 <2c516888-de4f-4dd7-b1c0-fe56bb03f754@googlegroups.com>
Message-ID: <85610k8asc.fsf@benfinney.id.au>

Andr? Roberge <andre.roberge at gmail.com> writes:

> In Python, a "variable" is a name given to an object. In Python, the
> "=" sign is used to assign a name to an object: the name is on the
> left-hand side, and the object is on the right hand side. Multiple
> names can be assigned to the same object.

Take care with the directionality of those statements.

In Python we don't give the name *to* the object, which would imply that
the object ?has? that name in some sense. The object is totally
unaffected, and assignment does not give the object any knowledge about
that name.

We also don't assign names *to* objects; if anything, we assign the
object to the name.

It is the name that ?has? the object. Or perhaps less confusingly, the
name is *bound to* the object.

It is frequently a point of confusion that assignment *never* affects
the object, so it's best to avoid giving that false impression.

> In the example you gave, "a" is a name given to the object "10" which
> is an integer.

Rather, I'd prefer to say that ?a? now refers to the object ?10?. The
object ?10? was not ?given? anything.

-- 
 \       ?When I get new information, I change my position. What, sir, |
  `\             do you do with new information?? ?John Maynard Keynes |
_o__)                                                                  |
Ben Finney



From lac at openend.se  Sun Nov 29 21:51:28 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 30 Nov 2015 03:51:28 +0100
Subject: How can I count word frequency in a web site?
In-Reply-To: <AE33E0E3-35FA-4C1B-A708-BFD2F83A55D2@gmail.com>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
 <AE33E0E3-35FA-4C1B-A708-BFD2F83A55D2@gmail.com>
Message-ID: <201511300251.tAU2pSBS016224@fido.openend.se>

In a message of Sun, 29 Nov 2015 21:31:49 -0500, Cem Karan writes:
>You might want to look into Beautiful Soup (https://pypi.python.org/pypi/beautifulsoup4), which is an HTML screen-scraping tool.  I've never used it, but I've heard good things about it.
>
>Good luck,
>Cem Karan

http://codereview.stackexchange.com/questions/73887/finding-the-occurrences-of-all-words-in-movie-scripts

scrapes a site of movie scripts and then spits out the 10 most common
words.  I suspect the OP could modify this script to suit his or her needs.

Laura


From ryanshuell at gmail.com  Sun Nov 29 21:54:11 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Sun, 29 Nov 2015 18:54:11 -0800 (PST)
Subject: How can I count word frequency in a web site?
In-Reply-To: <mailman.14.1448850720.14615.python-list@python.org>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
 <mailman.14.1448850720.14615.python-list@python.org>
Message-ID: <88ec2ba2-6b06-421b-89d5-ece408bb4c8e@googlegroups.com>

On Sunday, November 29, 2015 at 9:32:22 PM UTC-5, Cem Karan wrote:
> You might want to look into Beautiful Soup (https://pypi.python.org/pypi/beautifulsoup4), which is an HTML screen-scraping tool.  I've never used it, but I've heard good things about it.
> 
> Good luck,
> Cem Karan
> 
> On Nov 29, 2015, at 7:49 PM, ryguy7272 wrote:
> 
> > I'm trying to figure out how to count words in a web site.  Here is a sample of the link I want to scrape data from and count specific words.
> > http://finance.yahoo.com/q/h?s=STRP+Headlines
> > 
> > I only want to count certain words, like 'fraud', 'lawsuit', etc.  I want to have a way to control for specific words.  I have a couple Python scripts that do this for a text file, but not for a web site.  I can post that, if that's helpful.
> > 
> > -- 
> > https://mail.python.org/mailman/listinfo/python-list

Ok, this small script will grab everything from the link.

import requests
from bs4 import BeautifulSoup
r = requests.get("http://finance.yahoo.com/q/h?s=STRP+Headlines")
soup = BeautifulSoup(r.content)
htmltext = soup.prettify()
print htmltext


Now, how can I count specific words like 'fraud' and 'lawsuit'?


From python at mrabarnett.plus.com  Sun Nov 29 22:23:34 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Mon, 30 Nov 2015 03:23:34 +0000
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <565BB71D.1010303@medimorphosis.com.au>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
 <11d4423f-7912-426c-9d20-d2cb5efba18b@googlegroups.com>
 <565BB71D.1010303@medimorphosis.com.au>
Message-ID: <565BC136.1050708@mrabarnett.plus.com>

On 2015-11-30 02:40, Rob Hills wrote:
> A program I am writing at present does exactly this and I simply do
> multiple calls to string.replace (see below)
>
> On 30/11/15 10:31, Mr Zaug wrote:
>> I seem to be heading in this direction.
>>
>> #!/usr/bin/env python
>> import re
>> from os.path import exists
>>
>> script, template_file = argv
>> print "Opening the template file..."
>>
>> with open (template_file, "r") as a_string:
>>     data=a_string.read().replace('BRAND', 'Fluxotine')
>
>          data=data.replace('STRING_2', 'New String 2')
>          data=data.replace('STRING_3', 'New String 3')
>
>> print(data)
>>
>> So now the challenge is to use the read().replace magic for multiple values.
>
> It's crude, but it works well for me!
>
You do need to watch out for matches that are part of something else.

For example, if you had this:

     template = "REPLACE_THIS but DONT_REPLACE_THIS"

and you did:

     result = template.replace("REPLACE_THIS", "Python")

you would get:

     "Python but DONT_Python"



From marko at pacujo.net  Mon Nov 30 00:28:06 2015
From: marko at pacujo.net (Marko Rauhamaa)
Date: Mon, 30 Nov 2015 07:28:06 +0200
Subject: variable vs. object
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <87y4dgys2h.fsf@elektro.pacujo.net>

fl <rxjwg98 at gmail.com>:

> I read several parts on line about Python that everything in Python is
> an object.

Python has two distinct entities: objects and references.

All numbers, strings, classes, modules, class instances, files etc are
objects.

Variables, however, are not objects. They are references. Here are
different references:

   a                  # variable
   a.x                # attribute
   a[3]               # subscription

> Yes, it is a key difference with other languages.

Python shares this feature with many higher-level languages.


Marko


From motoom at xs4all.nl  Mon Nov 30 02:56:32 2015
From: motoom at xs4all.nl (Michiel Overtoom)
Date: Mon, 30 Nov 2015 08:56:32 +0100
Subject: How can I count word frequency in a web site?
In-Reply-To: <88ec2ba2-6b06-421b-89d5-ece408bb4c8e@googlegroups.com>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
 <mailman.14.1448850720.14615.python-list@python.org>
 <88ec2ba2-6b06-421b-89d5-ece408bb4c8e@googlegroups.com>
Message-ID: <3EE25A27-CCBF-4B3B-B6D2-F649086050F5@xs4all.nl>


> On 30 Nov 2015, at 03:54, ryguy7272 <ryanshuell at gmail.com> wrote:
> 
> Now, how can I count specific words like 'fraud' and 'lawsuit'?

- convert the page to plain text
- remove any interpunction
- split into words
- see what words occur
- enumerate all the words and increase a counter for each word

Something like this:

s = """Today we're rounding out our planetary tour with ice giants Uranus
and Neptune. Both have small rocky cores, thick mantles of ammonia, water,
and methane, and atmospheres that make them look greenish and blue. Uranus
has a truly weird rotation and relatively dull weather, while Neptune has
clouds and storms whipped by tremendous winds. Both have rings and moons,
with Neptune's Triton probably being a captured iceball that has active
geology."""

import collections
cleaned = s.lower().replace("\n", " ").replace(".", "").replace(",", "").replace("'", " ")
count = collections.Counter(cleaned.split(" "))
for interesting in ("neptune", "and"):
    print "The word '%s' occurs %d times" % (interesting, count[interesting])


# Outputs:

The word 'neptune' occurs 3 times
The word 'and' occurs 7 times






From gandalf at shopzeus.com  Mon Nov 30 03:09:32 2015
From: gandalf at shopzeus.com (=?UTF-8?Q?Nagy_L=c3=a1szl=c3=b3_Zsolt?=)
Date: Mon, 30 Nov 2015 09:09:32 +0100
Subject: variable vs. object
In-Reply-To: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <565C043C.1000003@shopzeus.com>


> a=10
>
> 'a' is an integer. Is it an object too?
In Python, objects have an identity. When you do "a=10" then you *bind*
the object to the name *a*. By "variable", the documentation refers to a
name that was bound to an object. This is different from many other low
level languages. For example: in C, you can do

a=10;

And it will "set the value of the variable 'a' to 10". In other words:
"a" is not just a name, it refers to a certain location in memory where
an integer value is stored. And in C, it is not an object but a value of
a built-in type.

In contrast, this is what happens in Python:

  * An "Integer" object is constructed with the value 10.
  * This object is then bound to the name "a".

The key point is that "variables" are just names that may reference to
objects. There is a distinction between names and objects. Strictly
speaking, you cannot "set the value of a variable", because variables do
not hold values. They just refer to objects. In Python, you can only
"create an object", or "change the state of an object", and "bind a name
to an object".


From rosuav at gmail.com  Mon Nov 30 03:19:18 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 30 Nov 2015 19:19:18 +1100
Subject: variable vs. object
In-Reply-To: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
References: <2b4696d5-c9fb-4ca6-92a3-564e47712d59@googlegroups.com>
Message-ID: <CAPTjJmq0PrfdVVdy1K2axBsoSiVmD_BXcegHdYAd3RG=96NXNQ@mail.gmail.com>

On Mon, Nov 30, 2015 at 1:06 PM, fl <rxjwg98 at gmail.com> wrote:
> For example,
>
> a=10
>
> 'a' is an integer. Is it an object too?

Other people have explained the difference between the name "a" and
the object it's bound to... but to the extent that "a" is an integer,
yes it most definitely is an object. To be specific, the integer 10 is
an object, as you can see thus:

>>> a = 10
>>> a.to_bytes(4, "big")
b'\x00\x00\x00\n'
>>> (a*12+8).to_bytes(4,"big")
b'\x00\x00\x00\x80'

Every expression [1] in Python has a value which is some sort of
object, so you can do method calls on anything at all. Sometimes this
looks a bit odd, but it does work:

>>> 7.25.as_integer_ratio()
(29, 4)

The floating-point number 7.25 is represented in Python as a float
object, and float objects have methods, same as all objects do. In
this case, I've asked Python to tell me what this number would be as a
fraction (ratio) of integers - 29/4 is equal to 7.25, so that's what
it returns.

So yes! It is an object. Everything is an object!

ChrisA

[1] To silence the nitpickers: An expression could raise an exception,
or not terminate at all. As Grandpa said in The Princess Bride, you're
very clever, now shut up.


From marco.kaulea at gmail.com  Mon Nov 30 03:42:01 2015
From: marco.kaulea at gmail.com (Marco Kaulea)
Date: Mon, 30 Nov 2015 09:42:01 +0100
Subject: New JSON encoding method proposal for custom objects
In-Reply-To: <n3fnru$5sf$3@dont-email.me>
References: <aac1b6e8-e294-4916-9485-ffc031c3aeb3@googlegroups.com>
 <n3fnru$5sf$3@dont-email.me>
Message-ID: <CAF0cjT_gP5SiZt2YepMo-Rh1+qz1Ny6kbYs5XTDuByPHuhNp7A@mail.gmail.com>

Hi,

I think his goal is not to load the data back into python, but to use
it to provide some
kind of REST-Style interface. An example would be, if you have a class
instance of
a record of a movie, that it could be simply encoded and send over the
wire to display.
Without necessarily recreating the class on the other end.
This would prevent any security risks from the deserialization.

On Sun, Nov 29, 2015 at 9:40 PM, Denis McMahon <denismfmcmahon at gmail.com> wrote:
> That's all well and good, but firstly you need to both dumps and loads to
> work properly with json, and secondly there's no mechanism in json that
> tells you what class of object you have.

But I am not sure how useful that PEP/Change would be, assuming the
code in Peter's response
works.

- Marco Kaulea


From rosuav at gmail.com  Mon Nov 30 03:44:50 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 30 Nov 2015 19:44:50 +1100
Subject: Caret key quits idle on pt keyboard
In-Reply-To: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
References: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
Message-ID: <CAPTjJmoQZGaJyq9PqE9=kNcnGXCpy7e3ncuOYkByU6pCmwznMA@mail.gmail.com>

On Mon, Nov 30, 2015 at 12:30 AM, Osvaldo Dias dos Santos via
Python-list <python-list at python.org> wrote:
> I can?t enter a caret in regex on a Portuguese keyboard because by pressing it, IDLE quits.
> Any help ?

Hmm. This could be part of the known issues with Tk (on which Idle
depends) and non-BMP characters, but a caret should be safe. What OS
and Python are you running? Can you pull up a terminal (aka command
prompt or console) and run "python3 -m idlelib.idle"? (Or "python2 -m
idlelib.idle" if you're using Python 2.7.) Then try it again, and see
if there's an exception traceback shown in the terminal.

If you can't get Idle to start from a terminal, try opening Python's
interactive mode (if you have a standard Windows installation, you
should have a Python command line in the Start menu). From there, type
"import idlelib.idle" and it should fire up Idle.

ChrisA


From rosuav at gmail.com  Mon Nov 30 03:48:38 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Mon, 30 Nov 2015 19:48:38 +1100
Subject: convert php in to python
In-Reply-To: <CAP9M=4BabE0gg5svMB5rQJacAK-vEGR7_4suaJQ45u9NqwHqaQ@mail.gmail.com>
References: <CAP9M=4B6oBxOG1g8E2WJSKEtCNV=WcowvU_EO7sU=eA3jaMF1w@mail.gmail.com>
 <CAP9M=4BabE0gg5svMB5rQJacAK-vEGR7_4suaJQ45u9NqwHqaQ@mail.gmail.com>
Message-ID: <CAPTjJmrXk5-iZXCRK7aejixmO0uyTPiCDfMKwNLNRh2_2AhnVQ@mail.gmail.com>

On Fri, Nov 27, 2015 at 11:52 PM, RENISH RUDANI <delphicr at gmail.com> wrote:
> Please help me to convert this code in python.
>
>
> *Thanks & Regards,*
>
> *Renish Rudani*
>
> *Action Speaks Louder than Words*

Sure.

#!/usr/bin/python3
"""Emit no output"""

You didn't provide any PHP code, so the equivalent Python code is
actually an empty file. I put in a docstring and a shebang so you'd be
able to find what I wrote.

It's possible you included an attachment, but attachments don't always
survive as far as the newsgroup/mailing list.

Translating code from one language to another usually requires
comprehension of what the code's trying to accomplish. You might have
to dig into the code a bit and get to know it, and then recreate it in
Python. It's not a simple question, unless the code itself is
trivially simple.

Good luck! At least you're migrating to a better language.

ChrisA


From harvesting at is.invalid  Mon Nov 30 03:51:13 2015
From: harvesting at is.invalid (Jussi Piitulainen)
Date: Mon, 30 Nov 2015 10:51:13 +0200
Subject: I can't understand re.sub
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
 <mailman.26.1448872519.14615.python-list@python.org>
Message-ID: <lf54mg3eupq.fsf@ling.helsinki.fi>

Erik writes:

> On 29/11/15 21:36, Mr Zaug wrote:
>> This should be simple, right?
>
> It is. And it could be even simpler if you don't bother with regexes
> at all (if your input is as fixed as you say it is):
>
> >>> foo = "foo bar baz spam CONTENT_PATH bar spam"
> >>> ' Substitute '.join(foo.split(' CONTENT_PATH ', 1))
> 'foo bar baz spam Substitute bar spam'

Surely the straight thing to say is:

   >>> foo.replace(' CONTENT_PATH ', ' Substitute ')
   'foo bar baz spam Substitute bar spam'

But there was no guarantee of spaces around the target. If you wish to,
say, replace "spam" in your foo with "REDACTED" but leave it intact in
"May the spammer be prosecuted", a regex might be attractive after all.


From __peter__ at web.de  Mon Nov 30 04:14:16 2015
From: __peter__ at web.de (Peter Otten)
Date: Mon, 30 Nov 2015 10:14:16 +0100
Subject: Generate config file from template using Python search and
 replace.
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
 <0dd0db34-7f8f-4e8b-ad6a-c82ad19c2e5e@googlegroups.com>
Message-ID: <n3h417$srs$1@ger.gmane.org>

Mr Zaug wrote:

> On Sunday, November 29, 2015 at 5:50:51 PM UTC-5, Peter Otten wrote:
>> Mr Zaug wrote:
>> 
>> > When I run this script on OS X El Capitan, I see,
>> >   
>> >   # permission sensitive cache
>> >   $include "_dispatcher_shared_auth-checker:
>> > 
>> > Was I supposed to incorporate it into the script I posted?
>> 
>> Are you referring to my post? I'm sorry, I can't make sense of your
>> question.
> 
> Yes. The snippet you posted went way over my head. When I ran it, it
> printed
> 
> # permission sensitive cache
>   $include "_dispatcher_shared_auth-checker:

It's hard to tell from that problem description what might have gone wrong. 
However:

In your template file you have to enclose all words you want to replace in 
braces ("you have foo options" becomes "you have {foo} options"), to replace 
all literal { with {{ and all literal } with }}.

Did you do that?



From cescus92 at gmail.com  Mon Nov 30 07:35:13 2015
From: cescus92 at gmail.com (cescus92 at gmail.com)
Date: Mon, 30 Nov 2015 04:35:13 -0800 (PST)
Subject: New JSON encoding method proposal for custom objects
In-Reply-To: <mailman.32.1448873773.14615.python-list@python.org>
References: <aac1b6e8-e294-4916-9485-ffc031c3aeb3@googlegroups.com>
 <n3fnru$5sf$3@dont-email.me>
 <mailman.32.1448873773.14615.python-list@python.org>
Message-ID: <6f5cd8a5-6e14-4069-8dfe-4a1a00c05827@googlegroups.com>



Hello everyone and thank you for your interest!

The Peter's code is very similar to what I think the default JSON encoder should be.

The advantage of the method that I propose is that you should not care anymore about which encoder you're going to use even in case of different class instances. Imagine if you could just do

  json.dumps({[1,2,3], Obj(), [DifferentObj()] })

Probably it doesn't worth a PEP but it's a very small change that can be great for making painless REST interfaces as Marco underlined (it was exactly what I was meaning, thanks)!

Denis, the way back is not considered in my proposal. But using the standard json.loads() could be nice enough! :)

> Go to python-ideas for a lengthy discussion ;)
Where can I find it?

Thank you again, I hope now my idea is clearer!


From ryanshuell at gmail.com  Mon Nov 30 10:04:11 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Mon, 30 Nov 2015 07:04:11 -0800 (PST)
Subject: How can I count word frequency in a web site?
In-Reply-To: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
Message-ID: <a9dbdd7e-6c32-49aa-ae6c-9a4f42b8e497@googlegroups.com>

On Sunday, November 29, 2015 at 7:49:40 PM UTC-5, ryguy7272 wrote:
> I'm trying to figure out how to count words in a web site.  Here is a sample of the link I want to scrape data from and count specific words.
> http://finance.yahoo.com/q/h?s=STRP+Headlines
> 
> I only want to count certain words, like 'fraud', 'lawsuit', etc.  I want to have a way to control for specific words.  I have a couple Python scripts that do this for a text file, but not for a web site.  I can post that, if that's helpful.


This works great!  Thanks for sharing!!


From ryanshuell at gmail.com  Mon Nov 30 10:04:50 2015
From: ryanshuell at gmail.com (ryguy7272)
Date: Mon, 30 Nov 2015 07:04:50 -0800 (PST)
Subject: How can I count word frequency in a web site?
In-Reply-To: <mailman.18.1448851896.14615.python-list@python.org>
References: <6851e3b8-0d46-4808-9f7f-372b71bf327c@googlegroups.com>
 <AE33E0E3-35FA-4C1B-A708-BFD2F83A55D2@gmail.com>
 <mailman.18.1448851896.14615.python-list@python.org>
Message-ID: <b67bd51c-9f92-471c-b9ca-73292a8315d0@googlegroups.com>

On Sunday, November 29, 2015 at 9:51:46 PM UTC-5, Laura Creighton wrote:
> In a message of Sun, 29 Nov 2015 21:31:49 -0500, Cem Karan writes:
> >You might want to look into Beautiful Soup (https://pypi.python.org/pypi/beautifulsoup4), which is an HTML screen-scraping tool.  I've never used it, but I've heard good things about it.
> >
> >Good luck,
> >Cem Karan
> 
> http://codereview.stackexchange.com/questions/73887/finding-the-occurrences-of-all-words-in-movie-scripts
> 
> scrapes a site of movie scripts and then spits out the 10 most common
> words.  I suspect the OP could modify this script to suit his or her needs.
> 
> Laura


Thanks Laura!


From random832 at fastmail.com  Mon Nov 30 10:10:26 2015
From: random832 at fastmail.com (Random832)
Date: Mon, 30 Nov 2015 15:10:26 +0000 (UTC)
Subject: Caret key quits idle on pt keyboard
References: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
 <CAPTjJmoQZGaJyq9PqE9=kNcnGXCpy7e3ncuOYkByU6pCmwznMA@mail.gmail.com>
Message-ID: <n3hot2$fgb$1@ger.gmane.org>

On 2015-11-30, Chris Angelico <rosuav at gmail.com> wrote:
> Hmm. This could be part of the known issues with Tk (on which Idle
> depends) and non-BMP characters, but a caret should be safe.

Is there a known issue with dead keys? From what I can find the
Portuguese keyboard doesn't have a "proper" caret, it has a
circumflex dead key which you can press space or any non-vowel to
get a caret.  Seems to work fine for me though.



From rosuav at gmail.com  Mon Nov 30 10:57:15 2015
From: rosuav at gmail.com (Chris Angelico)
Date: Tue, 1 Dec 2015 02:57:15 +1100
Subject: Caret key quits idle on pt keyboard
In-Reply-To: <n3hot2$fgb$1@ger.gmane.org>
References: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
 <CAPTjJmoQZGaJyq9PqE9=kNcnGXCpy7e3ncuOYkByU6pCmwznMA@mail.gmail.com>
 <n3hot2$fgb$1@ger.gmane.org>
Message-ID: <CAPTjJmoRAZ5dR0wNgU2ZmyYLNJSW8_tN71bg_NHJw7O4HrYztw@mail.gmail.com>

On Tue, Dec 1, 2015 at 2:10 AM, Random832 <random832 at fastmail.com> wrote:
> On 2015-11-30, Chris Angelico <rosuav at gmail.com> wrote:
>> Hmm. This could be part of the known issues with Tk (on which Idle
>> depends) and non-BMP characters, but a caret should be safe.
>
> Is there a known issue with dead keys? From what I can find the
> Portuguese keyboard doesn't have a "proper" caret, it has a
> circumflex dead key which you can press space or any non-vowel to
> get a caret.  Seems to work fine for me though.

Ah, that might explain it. I don't have a system to test it on,
though. Definitely needs OS/Python version details.

ChrisA


From lac at openend.se  Mon Nov 30 11:13:00 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 30 Nov 2015 17:13:00 +0100
Subject: Caret key quits idle on pt keyboard
In-Reply-To: <CAPTjJmoRAZ5dR0wNgU2ZmyYLNJSW8_tN71bg_NHJw7O4HrYztw@mail.gmail.com>
References: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
 <CAPTjJmoQZGaJyq9PqE9=kNcnGXCpy7e3ncuOYkByU6pCmwznMA@mail.gmail.com>
 <n3hot2$fgb$1@ger.gmane.org>
 <CAPTjJmoRAZ5dR0wNgU2ZmyYLNJSW8_tN71bg_NHJw7O4HrYztw@mail.gmail.com>
Message-ID: <201511301613.tAUGD09O014134@fido.openend.se>

In a message of Tue, 01 Dec 2015 02:57:15 +1100, Chris Angelico writes:
>On Tue, Dec 1, 2015 at 2:10 AM, Random832 <random832 at fastmail.com> wrote:
>> On 2015-11-30, Chris Angelico <rosuav at gmail.com> wrote:
>>> Hmm. This could be part of the known issues with Tk (on which Idle
>>> depends) and non-BMP characters, but a caret should be safe.
>>
>> Is there a known issue with dead keys? From what I can find the
>> Portuguese keyboard doesn't have a "proper" caret, it has a
>> circumflex dead key which you can press space or any non-vowel to
>> get a caret.  Seems to work fine for me though.
>
>Ah, that might explain it. I don't have a system to test it on,
>though. Definitely needs OS/Python version details.
>
>ChrisA

I have a Swedish keyboard which has a caret dead-key that works 
as Random832 describes.  Idle works perfectly well for me.

There are a bunch of MacOS specific idle keyboard bugs.  I wonder
if this is (possibly another) one of them.

Laura



From carl at oddbird.net  Mon Nov 30 11:32:27 2015
From: carl at oddbird.net (Carl Meyer)
Date: Mon, 30 Nov 2015 09:32:27 -0700
Subject: Python 3 virtualenvs
In-Reply-To: <201511291412.tATECKN8006265@fido.openend.se>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <201511291412.tATECKN8006265@fido.openend.se>
Message-ID: <565C7A1B.2070202@oddbird.net>

Hi Laura,

On 11/29/2015 07:12 AM, Laura Creighton wrote:
> pyenv is going away.  python -m venv is the preferred way to get a venv
> 
> https://bugs.python.org/issue25154
> 
> Of course if you try it, you may get:
> 
>   Error: Command '['<directory>/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1
> 
> which turns out to mean:
> 
> Your Python isn't configured with ensure-pip!

AFAIK "isn't configured with ensurepip" is a thing which is only done to
Python by some downstream distributors (e.g. Linux packagers). If they
remove ensurepip, it should be their responsibility to also fix the venv
module accordingly (at least enough to provide a useful error message).
So I believe that's a bug that should be filed against whoever is
distributing the Python you're using.

> Right now, I personally don't know why there is a venv at all.

Because virtualenv is an ugly hack which is difficult to maintain (I
should know, I used to maintain it). In order to work at all, virtualenv
maintains its own patched copy of several stdlib modules (based
originally on Python 2.4(?) and modified since then) and uses them
instead of the version distributed with whatever version of Python you
are using. Some other stdlib modules it monkeypatches. As you might
expect, this regularly causes problems when new Python versions are
released, requiring even more hacks piled atop the previous ones.

It's a real testament to the dedication of the current virtualenv
maintainers (thank you, PyPA!) that it even works at all.

The built-in venv module in Python 3.3+ fixes that by building a minimal
level of support for virtual environments directly into the Python
interpreter and stdlib, removing the need for (monkey)patching. Of
course that interpreter support isn't available in Pythons prior to 3.3,
which is why virtualenv remains much more popular today.

(Also, the first version of venv in Python 3.3 didn't automatically
install pip into the envs, which made them less useful, because at that
point pip was a purely third-party project. That's been fixed with
ensurepip in Python 3.4+).

I very much hope that some day in the future, when all new Python
projects are in Python 3, almost everyone will use venv, and virtualenv
will be relevant only to those maintaining legacy Python 2 projects.

There has been some work towards writing a transitional version of
virtualenv that looks the same to users, but (under the hood) uses the
old code only for 2.x and uses venv for Python 3.

>  Despite
> the similarity of names, it doesn't seem to be about doing what virtualenv
> does.

I don't know what you mean by this. Venv is intended to do _exactly_
what virtualenv does, only better. Unless by "what virtualenv does" you
mean "also support Python 2."

> I think it is only meant to be used by people who want to install
> packages but not site-wide, but I am not sure about that.

I don't know what you mean by this either. Isn't the ability to "install
packages but not site-wide" precisely what virtualenv (and venv) give you?

> I don't think
> there are any plans to give venv the functionality of virtualenv,

What functionality do you mean?

> so
> presumably there are people who like it just fine the way it is now.
> They must have very different needs than I do.

I don't know, since you never said what it is about venv that doesn't
meet your needs :-)

Carl

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From rxjwg98 at gmail.com  Mon Nov 30 11:44:05 2015
From: rxjwg98 at gmail.com (fl)
Date: Mon, 30 Nov 2015 08:44:05 -0800 (PST)
Subject: Question about code writing '% i, callback'
Message-ID: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>

Hi,

I come across the following code snippet.





for i in range(10):
    def callback():
        print "clicked button", i
    UI.Button("button %s" % i, callback)




The content inside parenthesis in last line is strange to me. 

"button %s" % i, callback


That is, the writing looks like recognized as three items when I try with a
class definition (it can run with this):

class buibutton():
    print 'sd'
    def __nonzero__(self):
       return False
       
    def Button(str, ii, callbackk):
        
        return


Could you explain it to me?

The link is here:

http://effbot.org/zone/default-values.htm

Thanks,


From zachary.ware+pylist at gmail.com  Mon Nov 30 11:53:08 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 30 Nov 2015 10:53:08 -0600
Subject: Question about code writing '% i, callback'
In-Reply-To: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
Message-ID: <CAKJDb-Pd-fU+aj3nzgjm_D5UBow6X5BN=idotu5T8=0mj_7JcA@mail.gmail.com>

On Mon, Nov 30, 2015 at 10:44 AM, fl <rxjwg98 at gmail.com> wrote:
> The content inside parenthesis in last line is strange to me.
>
> "button %s" % i, callback

https://docs.python.org/library/stdtypes.html#printf-style-string-formatting

-- 
Zach


From zachary.ware+pylist at gmail.com  Mon Nov 30 11:54:53 2015
From: zachary.ware+pylist at gmail.com (Zachary Ware)
Date: Mon, 30 Nov 2015 10:54:53 -0600
Subject: Question about code writing '% i, callback'
In-Reply-To: <CAKJDb-Pd-fU+aj3nzgjm_D5UBow6X5BN=idotu5T8=0mj_7JcA@mail.gmail.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
 <CAKJDb-Pd-fU+aj3nzgjm_D5UBow6X5BN=idotu5T8=0mj_7JcA@mail.gmail.com>
Message-ID: <CAKJDb-N1HvFcKEQW8oCxa68b31FCwq4rb_dTwRwrz0bX__BHRw@mail.gmail.com>

On Mon, Nov 30, 2015 at 10:53 AM, Zachary Ware
<zachary.ware+pylist at gmail.com> wrote:
> On Mon, Nov 30, 2015 at 10:44 AM, fl <rxjwg98 at gmail.com> wrote:
>> The content inside parenthesis in last line is strange to me.
>>
>> "button %s" % i, callback
>
> https://docs.python.org/library/stdtypes.html#printf-style-string-formatting

Sorry, should have tested that link before sending.  That should be either

https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting

or

https://docs.python.org/2/library/stdtypes.html#string-formatting-operations

-- 
Zach


From ian.g.kelly at gmail.com  Mon Nov 30 12:01:55 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 30 Nov 2015 11:01:55 -0600
Subject: Question about code writing '% i, callback'
In-Reply-To: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
Message-ID: <CALwzidn0wCAUd9zQRYHp3Lgg3hYBY769aJF-OkZxgWxdNXi4Nw@mail.gmail.com>

On Mon, Nov 30, 2015 at 10:44 AM, fl <rxjwg98 at gmail.com> wrote:
> I come across the following code snippet.
>
> for i in range(10):
>     def callback():
>         print "clicked button", i
>     UI.Button("button %s" % i, callback)
>
> The content inside parenthesis in last line is strange to me.
>
> "button %s" % i, callback

These are the arguments being passed to UI.Button. The first argument is:

    "button %s" % i

This is an example of printf-style string formatting. See the link
that Zachary posted.

The second argument is the function named callback.

> That is, the writing looks like recognized as three items when I try with a
> class definition (it can run with this):
>
> class buibutton():
>     print 'sd'
>     def __nonzero__(self):
>        return False
>
>     def Button(str, ii, callbackk):
>
>         return
>
>
> Could you explain it to me?

How is this related to the example above?

Here, Button is defined as a method of a class. Since it's a method,
the first parameter is the "self" parameter, which will implicitly
take the value of the class instance that you're calling the Button
method on. If you're trying to call this like above, then the second
parameter "ii" will take the value of the string from the example
above, and callbackk will take the value of the callback argument from
above.

Thus, the method that you've defined has three parameters but only
takes two explicit arguments.


From framstag at rus.uni-stuttgart.de  Mon Nov 30 12:15:04 2015
From: framstag at rus.uni-stuttgart.de (Ulli Horlacher)
Date: Mon, 30 Nov 2015 17:15:04 +0000 (UTC)
Subject: static variables
Message-ID: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>


I try to to implement a "static variable" inside a function:

def main():
  a(1)
  a(2)
  a()
  print(a.x)
  if 'a.x' in globals(): print('global variable')
  if 'a.x' in locals():  print('local variable')

def a(x=None):
  if not x is None: a.x = x
  print(':',a.x)

main()

When I run this code, I get:

: 1
: 2
: 2
2

This is exactly what I expect.
But what is a.x?
It is neither a variable in globals() nor in locals()


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum IZUS/TIK         E-Mail: horlacher at tik.uni-stuttgart.de
Universitaet Stuttgart         Tel:    ++49-711-68565868
Allmandring 30a                Fax:    ++49-711-682357
70550 Stuttgart (Germany)      WWW:    http://www.tik.uni-stuttgart.de/


From lac at openend.se  Mon Nov 30 12:20:47 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 30 Nov 2015 18:20:47 +0100
Subject: Python 3 virtualenvs
In-Reply-To: <565C7A1B.2070202@oddbird.net>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <201511291412.tATECKN8006265@fido.openend.se> <565C7A1B.2070202@oddbird.net>
Message-ID: <201511301720.tAUHKlAe017071@fido.openend.se>

In a message of Mon, 30 Nov 2015 09:32:27 -0700, Carl Meyer writes:
>Hi Laura,

>I don't know what you mean by this. Venv is intended to do _exactly_
>what virtualenv does, only better. Unless by "what virtualenv does" you
>mean "also support Python 2."

That is exactly what I mean.

>> I think it is only meant to be used by people who want to install
>> packages but not site-wide, but I am not sure about that.
>
>I don't know what you mean by this either. Isn't the ability to "install
>packages but not site-wide" precisely what virtualenv (and venv) give you?

I rarely use it for that.  What I nearly always want is different
python interpreters.  CPython, PyPy, Jython for anything from 2.6 to
3.6.

Laura


From carl at oddbird.net  Mon Nov 30 12:28:46 2015
From: carl at oddbird.net (Carl Meyer)
Date: Mon, 30 Nov 2015 10:28:46 -0700
Subject: Python 3 virtualenvs
In-Reply-To: <201511301720.tAUHKlAe017071@fido.openend.se>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <201511291412.tATECKN8006265@fido.openend.se> <565C7A1B.2070202@oddbird.net>
 <201511301720.tAUHKlAe017071@fido.openend.se>
Message-ID: <565C874E.7060008@oddbird.net>

On 11/30/2015 10:20 AM, Laura Creighton wrote:
> In a message of Mon, 30 Nov 2015 09:32:27 -0700, Carl Meyer writes:
>>> I think it is only meant to be used by people who want to install
>>> packages but not site-wide, but I am not sure about that.
>>
>> I don't know what you mean by this either. Isn't the ability to "install
>> packages but not site-wide" precisely what virtualenv (and venv) give you?
> 
> I rarely use it for that.  What I nearly always want is different
> python interpreters.  CPython, PyPy, Jython for anything from 2.6 to
> 3.6.

If you just want the variety of interpreters, virtualenv doesn't give
you that -- you have to already have a given interpreter installed
system-wide for virtualenv to be able to use it. What virtualenv gives
you is isolated environments for package installations (which can use
any interpreter you have installed).

Venv does the same (and won't have any trouble with PyPy or Jython
either, once they reach Python 3.3 compatibility).

So I agree that for now you should be sticking with virtualenv (I use it
too), but I hope you'll take another look at venv a few years down the
road, if you find yourself in a situation where all the interpreters you
need are 3.3+.

(Or maybe virtualenv will make the transition sooner, and you'll start
using venv under the hood for 3.3+ without even realizing it.)

Carl

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From tjreedy at udel.edu  Mon Nov 30 12:30:03 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 30 Nov 2015 12:30:03 -0500
Subject: Caret key quits idle on pt keyboard
In-Reply-To: <201511301613.tAUGD09O014134@fido.openend.se>
References: <ADE3DE97-52FD-4A99-838D-4BEBCC5261D6@yahoo.com>
 <CAPTjJmoQZGaJyq9PqE9=kNcnGXCpy7e3ncuOYkByU6pCmwznMA@mail.gmail.com>
 <n3hot2$fgb$1@ger.gmane.org>
 <CAPTjJmoRAZ5dR0wNgU2ZmyYLNJSW8_tN71bg_NHJw7O4HrYztw@mail.gmail.com>
 <201511301613.tAUGD09O014134@fido.openend.se>
Message-ID: <n3i13n$810$1@ger.gmane.org>

On 11/30/2015 11:13 AM, Laura Creighton wrote:
> In a message of Tue, 01 Dec 2015 02:57:15 +1100, Chris Angelico writes:
>> On Tue, Dec 1, 2015 at 2:10 AM, Random832 <random832 at fastmail.com> wrote:
>>> On 2015-11-30, Chris Angelico <rosuav at gmail.com> wrote:
>>>> Hmm. This could be part of the known issues with Tk (on which Idle
>>>> depends) and non-BMP characters, but a caret should be safe.
>>>
>>> Is there a known issue with dead keys? From what I can find the
>>> Portuguese keyboard doesn't have a "proper" caret, it has a
>>> circumflex dead key which you can press space or any non-vowel to
>>> get a caret.  Seems to work fine for me though.

Older versions of tcl/tk had problems with some non-ascii keyboards. 
The fix was around 8.5.12.  The 8.5.9 that come with Mac does not have 
it.  Help | About Idle shows the tk version.

>> Ah, that might explain it. I don't have a system to test it on,
>> though. Definitely needs OS/Python version details.
>>
>> ChrisA
>
> I have a Swedish keyboard which has a caret dead-key that works
> as Random832 describes.  Idle works perfectly well for me.
>
> There are a bunch of MacOS specific idle keyboard bugs.  I wonder
> if this is (possibly another) one of them.

Some are fixed in the upcoming releases because Mark Roseman is a Mac 
user, tk expert, and now an IDLE contributor who submitted patches for 
the Mac bugs that bugged him.  Mac bugs not on the tracker are unlikely 
to be fixed, though.

-- 
Terry Jan Reedy



From jon+usenet at unequivocal.co.uk  Mon Nov 30 12:30:41 2015
From: jon+usenet at unequivocal.co.uk (Jon Ribbens)
Date: Mon, 30 Nov 2015 17:30:41 -0000 (UTC)
Subject: Python 3 virtualenvs
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <201511291412.tATECKN8006265@fido.openend.se>
 <565C7A1B.2070202@oddbird.net>
 <201511301720.tAUHKlAe017071@fido.openend.se>
 <mailman.43.1448904539.14615.python-list@python.org>
Message-ID: <slrnn5p22i.1t1.jon+usenet@frosty.unequivocal.co.uk>

On 2015-11-30, Carl Meyer <carl at oddbird.net> wrote:
> (Or maybe virtualenv will make the transition sooner, and you'll start
> using venv under the hood for 3.3+ without even realizing it.)

It does sound like that would be the ideal solution, and presumably
can't be very hard if venv is supposed to do exactly what virtualenv
does anyway - virtualenv just needs to say "if python >= 3.4 then
call venv".


From rxjwg98 at gmail.com  Mon Nov 30 12:36:09 2015
From: rxjwg98 at gmail.com (fl)
Date: Mon, 30 Nov 2015 09:36:09 -0800 (PST)
Subject: Question about code writing '% i, callback'
In-Reply-To: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
Message-ID: <f18de0eb-07f1-424a-90c3-62fbc9be128a@googlegroups.com>

On Monday, November 30, 2015 at 11:44:44 AM UTC-5, fl wrote:
> Hi,
> 
> I come across the following code snippet.
> 
> 
> 
> 
> 
> for i in range(10):
>     def callback():
>         print "clicked button", i
>     UI.Button("button %s" % i, callback)
> 
> 
> 
> 
> The content inside parenthesis in last line is strange to me. 
> 
> "button %s" % i, callback
> 
> 
> That is, the writing looks like recognized as three items when I try with a
> class definition (it can run with this):
> 
> class buibutton():
>     print 'sd'
>     def __nonzero__(self):
>        return False
>        
>     def Button(str, ii, callbackk):
>         
>         return
> 
> 
> Could you explain it to me?
> 
> The link is here:
> 
> http://effbot.org/zone/default-values.htm
> 
> Thanks,

Thanks for the replies. Now, I have the following code:



class buibutton():
    print 'sd'
    def __nonzero__(self):
       return False
       
    def Button(self, ii, callbackk):
        callbackk()
        return
UI=buibutton()


for i in range(10):
    def callback():
        print "clicked button", i
    UI.Button("button %s" % i, callback)
    

To my surprise, the output is not the original link expected. i.e. it is 
the same with binding to the current values:

for i in range(10):
    def callback(i=i):


I have the output for both:


%run "C:/Users/CCS6_1_Tiva_C/Python_prj0/uibutton1.py"
sd
clicked button 0
clicked button 1
clicked button 2
clicked button 3
clicked button 4
clicked button 5
clicked button 6
clicked button 7
clicked button 8
clicked button 9

%run "C:\Users\CCS6_1_Tiva_C\Python_prj0\uibutton0.py"
sd
clicked button 0
clicked button 1
clicked button 2
clicked button 3
clicked button 4
clicked button 5
clicked button 6
clicked button 7
clicked button 8
clicked button 9

I don't know why it does not have the not expected format output:

sd
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9
clicked button 9


Thanks,


From tjreedy at udel.edu  Mon Nov 30 12:36:56 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 30 Nov 2015 12:36:56 -0500
Subject: Question about code writing '% i, callback'
In-Reply-To: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
Message-ID: <n3i1gk$fk8$1@ger.gmane.org>

On 11/30/2015 11:44 AM, fl wrote:

> I come across the following code snippet.

> for i in range(10):
>      def callback():
>          print "clicked button", i
>      UI.Button("button %s" % i, callback)

> http://effbot.org/zone/default-values.htm

Note that the above is an intentional example of common buggy code.  It 
is followed by a version that works, with 'i=i' added to the callback 
header.

-- 
Terry Jan Reedy



From tjreedy at udel.edu  Mon Nov 30 12:38:40 2015
From: tjreedy at udel.edu (Terry Reedy)
Date: Mon, 30 Nov 2015 12:38:40 -0500
Subject: static variables
In-Reply-To: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>
References: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3i1jr$fk8$2@ger.gmane.org>

On 11/30/2015 12:15 PM, Ulli Horlacher wrote:
>
> I try to to implement a "static variable" inside a function:
>
> def main():
>    a(1)
>    a(2)
>    a()
>    print(a.x)
>    if 'a.x' in globals(): print('global variable')
>    if 'a.x' in locals():  print('local variable')
>
> def a(x=None):
>    if not x is None: a.x = x
>    print(':',a.x)
>
> main()
>
> When I run this code, I get:
>
> : 1
> : 2
> : 2
> 2
>
> This is exactly what I expect.
> But what is a.x?
> It is neither a variable in globals() nor in locals()

a.x is an attribute of the object a.


-- 
Terry Jan Reedy



From lac at openend.se  Mon Nov 30 12:46:21 2015
From: lac at openend.se (Laura Creighton)
Date: Mon, 30 Nov 2015 18:46:21 +0100
Subject: Python 3 virtualenvs
In-Reply-To: <565C874E.7060008@oddbird.net>
References: <1mekmrs.1xn5n6010b7a1xN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5jb72.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <1mem3lu.1327fd91org8tkN%real-not-anti-spam-address@apple-juice.co.uk>
 <slrnn5k8e4.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <8737vp0zh9.fsf@metapensiero.it>
 <mailman.7.1448800035.14615.python-list@python.org>
 <slrnn5lv6n.1t1.jon+usenet@frosty.unequivocal.co.uk>
 <201511291412.tATECKN8006265@fido.openend.se> <565C7A1B.2070202@oddbird.net>
 <201511301720.tAUHKlAe017071@fido.openend.se> <565C874E.7060008@oddbird.net>
Message-ID: <201511301746.tAUHkLRI017661@fido.openend.se>

In a message of Mon, 30 Nov 2015 10:28:46 -0700, Carl Meyer writes:

>So I agree that for now you should be sticking with virtualenv (I use it
>too), but I hope you'll take another look at venv a few years down the
>road, if you find yourself in a situation where all the interpreters you
>need are 3.3+.

I will, but these days I am playing with fades, which I only discovered
a week ago, when Facundo made an announcment.
https://pypi.python.org/pypi/fades/3

And it looks like this will make my life a whole lot easier.

Laura


From rxjwg98 at gmail.com  Mon Nov 30 12:50:42 2015
From: rxjwg98 at gmail.com (fl)
Date: Mon, 30 Nov 2015 09:50:42 -0800 (PST)
Subject: Question about code writing '% i, callback'
In-Reply-To: <mailman.45.1448905059.14615.python-list@python.org>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
 <mailman.45.1448905059.14615.python-list@python.org>
Message-ID: <06c312b2-a137-46e1-b31c-c9c2224224ad@googlegroups.com>

On Monday, November 30, 2015 at 12:37:52 PM UTC-5, Terry Reedy wrote:
> On 11/30/2015 11:44 AM, fl wrote:
> 
> > I come across the following code snippet.
> 
> > for i in range(10):
> >      def callback():
> >          print "clicked button", i
> >      UI.Button("button %s" % i, callback)
> 
> > http://effbot.org/zone/default-values.htm
> 
> Note that the above is an intentional example of common buggy code.  It 
> is followed by a version that works, with 'i=i' added to the callback 
> header.
> 
> -- 
> Terry Jan Reedy

With the following code, there is no bug as the original author said.


class buibutton():
    print 'sd'
    def __nonzero__(self):
       return False
       
    def Button(self, ii, callbackk):
        callbackk()
        return

for i in range(10):
    def callback():
        print "clicked button", i
    UI.Button("button %s" % i, callback)

only to find that all callbacks print the same value (most likely 9, in this case). 

Why does it have no bug?


From ian.g.kelly at gmail.com  Mon Nov 30 13:24:23 2015
From: ian.g.kelly at gmail.com (Ian Kelly)
Date: Mon, 30 Nov 2015 11:24:23 -0700
Subject: Question about code writing '% i, callback'
In-Reply-To: <f18de0eb-07f1-424a-90c3-62fbc9be128a@googlegroups.com>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
 <f18de0eb-07f1-424a-90c3-62fbc9be128a@googlegroups.com>
Message-ID: <CALwzidkw9kgW2PQ=jgX_=go2KjZn0eM0sroo50+V4LuORcjSxw@mail.gmail.com>

On Mon, Nov 30, 2015 at 10:36 AM, fl <rxjwg98 at gmail.com> wrote:
> Thanks for the replies. Now, I have the following code:
>
>
>
> class buibutton():
>     print 'sd'
>     def __nonzero__(self):
>        return False
>
>     def Button(self, ii, callbackk):
>         callbackk()
>         return
> UI=buibutton()
>
>
> for i in range(10):
>     def callback():
>         print "clicked button", i
>     UI.Button("button %s" % i, callback)
>
>
> To my surprise, the output is not the original link expected. i.e. it is
> the same with binding to the current values:

The callback function is being called immediately, in the body of the
loop, not stored and called later. The value of i in the closure has
not actually changed yet at the point you're calling it. If you
instead store the callback and call it later, you'll find that each
message says "button 9".


From rxjwg98 at gmail.com  Mon Nov 30 13:55:23 2015
From: rxjwg98 at gmail.com (fl)
Date: Mon, 30 Nov 2015 10:55:23 -0800 (PST)
Subject: Question about code writing '% i, callback'
In-Reply-To: <mailman.41.1448902962.14615.python-list@python.org>
References: <25af8ac3-5fc7-44bd-a73f-7a870b69515a@googlegroups.com>
 <mailman.41.1448902962.14615.python-list@python.org>
Message-ID: <53ef7ef4-cfec-4c91-a45c-5b847dde8fad@googlegroups.com>

On Monday, November 30, 2015 at 12:02:57 PM UTC-5, Ian wrote:
> On Mon, Nov 30, 2015 at 10:44 AM, fl <ail.com> wrote:
> > I come across the following code snippet.
> >
> > for i in range(10):
> >     def callback():
> >         print "clicked button", i
> >     UI.Button("button %s" % i, callback)
> >
> > The content inside parenthesis in last line is strange to me.
> >
> > "button %s" % i, callback
> 
> These are the arguments being passed to UI.Button. The first argument is:
> 
>     "button %s" % i
> 
> This is an example of printf-style string formatting. See the link
> that Zachary posted.
> 
> The second argument is the function named callback.
> 
> > That is, the writing looks like recognized as three items when I try with a
> > class definition (it can run with this):
> >
> > class buibutton():
> >     print 'sd'
> >     def __nonzero__(self):
> >        return False
> >
> >     def Button(str, ii, callbackk):
> >
> >         return
> >
> >
> > Could you explain it to me?
> 
> How is this related to the example above?
> 
> Here, Button is defined as a method of a class. Since it's a method,
> the first parameter is the "self" parameter, which will implicitly
> take the value of the class instance that you're calling the Button
> method on. If you're trying to call this like above, then the second
> parameter "ii" will take the value of the string from the example
> above, and callbackk will take the value of the callback argument from
> above.
> 
> Thus, the method that you've defined has three parameters but only
> takes two explicit arguments.

"How is this related to the example above? 

Here, Button is defined as a method of a class. Since it's a method, 
the first parameter is the "self" parameter, which will implicitly 
take the value of the class instance that you're calling the Button 
method on."

Thanks Ian. I created the class because I want to use the original example
line 

 UI.Button("button %s" % i, callback)

Is there another way to use the above line without my class definition?
I do feel that my created class does not match well with the above line
because the first item "button %s" does not fit __self__ in the class.
My understanding about the above line code may not correct. This may further
result in not the original bug pops up.

Thanks,


 




From bc at freeuk.com  Mon Nov 30 15:32:26 2015
From: bc at freeuk.com (BartC)
Date: Mon, 30 Nov 2015 20:32:26 +0000
Subject: static variables
In-Reply-To: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>
References: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>
Message-ID: <n3ibkd$nl0$1@dont-email.me>

On 30/11/2015 17:15, Ulli Horlacher wrote:
> def main():
>    a(1)
>    a(2)
>    a()
>    print(a.x)
>    if 'a.x' in globals(): print('global variable')
>    if 'a.x' in locals():  print('local variable')

Try this:

    if 'x' in a.__dict__:  print('attribute of a')

-- 
Bartc


From pcmanticore at gmail.com  Mon Nov 30 18:42:46 2015
From: pcmanticore at gmail.com (Claudiu Popa)
Date: Tue, 1 Dec 2015 01:42:46 +0200
Subject: Pylint 1.5.0 / Astroid 1.4.1 released
Message-ID: <CAMy=CLpp1SfTpkpktFyFVg0NwUZrq3LgXd75ZNqCyp7kDgjFAg@mail.gmail.com>

Hello,


I'm happy to announce you the release of Pylint 1.5.0,
respectively Astroid 1.4.1.

It's been over a year since the last major release
and the amount of changes that were brought into pylint
in this time is humongous, with over 30 new checks
and tons of bug fixes.

I would like to use this occasion for thanking for their contributions
the new committers who joined pylint's team in the past months,
ceridwen and Dmitry, as well as thanking the
contributors that made this release possible.

Here are some of the major changes of this release:

- We finally support Python 3.5 in both projects.

- We stopped depending on logilab-common, which
  means that users of the popular testing framework
  pytest will finally stop being confused by having
  two executables with the same name doing different
  things.

- Almost 30 new checks you might enjoy not having in
  your project. These checks fall into multiple categories,
  regarding maintainability, readability, recommendations
  for improving the code, as well as new type-checking
  capabilities. They are:

    'wrong-import-order', 'ungrouped-imports', 'wrong-import-position',
    'unneeded-not', 'simplifiable-if-condition', 'too-many-boolean-expressions'
    'too-many-nested-blocks', 'multiple-imports', 'duplicate-except',
    'using-constant-test', 'confusing-with-statement', 'singleton-comparison',
    'misplaced-comparison-constant', 'consider-using-enumerate',
    'nonlocal-and-global', 'continue-in-finally', 'misplaced-bare-raise',
    'nonlocal-without-binding', 'yield-inside-async-function',
    'too-many-star-expressions', 'invalid-star-assignment-target',
    'import-star-module-level, 'star-needs-assignment',
    'unexpected-special-method-signature', 'repeated-keyword'.

    Some new type checks for finding violations of the type system
    are 'unsubscriptable-object', 'unsupported-membership-test',
    'not-an-iterable', 'not-context-manager', 'not-async-context-manager',
    'duplicate-bases' and 'inconsistent-mro'.


- We also added a new 'extensions' component, which contains optional
  checkers that needs to be activated explicitly.

  These includes 'extensions.check_docs', which verifies a bunch of
  properties of the docstrings, such as checking that all function,
  method and constructor parameters are mentioned
  in the params and types part of the docstring. Also, it checks that
  there are no naming inconsistencies between the signature and
  the documentation, i.e. also report documented parameters that are missing
  in the signature. This is important to find cases where parameters are
  renamed only in the code, not in the documentation.

  Activate this checker with:

      --load-plugins=pylint.extensions.check_docs

Most of the work was put into astroid though, which got more capable in this
period of time. Unfortunately, more than half of the work that went into it was
postponed for astroid 1.6 and astroid 2.0, since it wasn't deemed stable
enough for this release.
New features worth mentioning are:

  - Python 3.5 support

  - some of the nodes were renamed in order to be more similar to
    builtin's ast module, such as Class to ClassDef, Function to
    FunctionDef Getattr to Attribute etc, the old names being slated
    for removal in astroid 2.0.
    This affects the plugins as well, since it means that the visit
    methods should use the new names instead (so visit_classdef for class).
    Old names are still supported in visit methods for a while, until
    pylint 2.0. Activating the warnings when running should result in
    spurious PendingDeprecationWarnings when using the old node names.

  - add proper grammatical names for `infered` and `ass_type` methods,
    namely `inferred` and `assign_type`.

    The old methods will raise PendingDeprecationWarning, being slated
    for removal in astroid 2.0.

  - we added a new convenience API, `astroid.parse`, which can be used
    to retrieve an astroid AST from a source code string, similar to how
    ast.parse can be used to obtain a Python AST from a source string.

  - There's a new separate step for transforms.

    Until now, the transforms were applied at the same time the tree was
    being built. This was problematic if the transform functions were
    using inference, since the inference was executed on a partially
    constructed tree, which led to failures when post-building
    information was needed.

  - Better support for understanding builtins.

    We're understanding a bunch of new builtins, but unfortunately
    most of them weren't released, since they weren't stable
    enough for now, due to some inherent problems that astroid
    has. The most important that's released though is the understanding
    of super, which means that we can now detect problems of sort:

    class A(B, C, D):
      def __init__(self):
          super(A, self).call_missing_method()

You can read the complete changelog here
https://bitbucket.org/logilab/astroid/raw/4f45b6fc4c23b80b4f7154add1b9d9cee3a54297/ChangeLog
and https://bitbucket.org/logilab/pylint/raw/2871c4d7084478b5db02f384e4e5167641c698f2/ChangeLog

Now with every release there's going to be new false positives or regressions
or things that could be improved. Don't hesitate to open an issue or to
send a PR if you notice something's amiss and we'll try to have new
bug fix releases as soon as possible (you might have noticed that's
astroid 1.4.1..)

As a final note, we're planning to switch to GitHub soon, which will mean an
improved CI for us, resulting in less maintenance pain.


Thank you for reading all this and enjoy pylinting!


Claudiu


From steve at pearwood.info  Mon Nov 30 20:00:46 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 01 Dec 2015 12:00:46 +1100
Subject: Is vars() the most useless Python built-in ever?
Message-ID: <565cf141$0$1612$c3e8da3$5496439d@news.astraweb.com>

I'm trying to understand why vars() exists. Does anyone use it?

Every time I try to use it, I find it doesn't quite do what I want. And even
if it did, there are more obvious and/or correct alternatives.

For instance, I want to check whether a particular name is an instance
attribute. So first I write:

"name" in obj.__dict__

but when I see the dunder name I think that's an implementation detail. And
sure enough, not all instances have a __dict__ (e.g. if it uses __slots__
instead) and so I re-write it as:

"name" in vars(obj)

but that also fails if obj has no instance __dict__.

But why am I looking just in the instance __dict__? Chances are I should be
looking for the attribute *anywhere* in the instance/class/superclass
hierarchy: 

hasattr(obj, "name")

Or, if you are worried about triggering dynamic attributes using
__getattr__, you can do this:

sentinel = object()
inspect.getattr_static(obj, "name", sentinel) is not sentinel

which only checks for pre-existing attributes without triggering
__getattr__, __getattribute__, or the descriptor protocol.


Either way, vars() doesn't solve the problem. What problem does it solve?



-- 
Steven



From steve at pearwood.info  Mon Nov 30 20:01:21 2015
From: steve at pearwood.info (Steven D'Aprano)
Date: Tue, 01 Dec 2015 12:01:21 +1100
Subject: static variables
References: <n3i06o$9ot$1@news2.informatik.uni-stuttgart.de>
 <n3ibkd$nl0$1@dont-email.me>
Message-ID: <565cf163$0$1612$c3e8da3$5496439d@news.astraweb.com>

On Tue, 1 Dec 2015 07:32 am, BartC wrote:

> On 30/11/2015 17:15, Ulli Horlacher wrote:
>> def main():
>>    a(1)
>>    a(2)
>>    a()
>>    print(a.x)
>>    if 'a.x' in globals(): print('global variable')
>>    if 'a.x' in locals():  print('local variable')
> 
> Try this:
> 
>     if 'x' in a.__dict__:  print('attribute of a')


That will work in this specific case, but it isn't guaranteed to always
work. Not all objects have a __dict__, even if they can hold attributes,
and not all attributes are stored in a __dict__.

A better and more general test is:

if hasattr(a, 'x'): print('attribute of a')

 

-- 
Steven



From jfong at ms4.hinet.net  Mon Nov 30 20:03:28 2015
From: jfong at ms4.hinet.net (jfong at ms4.hinet.net)
Date: Mon, 30 Nov 2015 17:03:28 -0800 (PST)
Subject: python response slow when running external DLL
In-Reply-To: <3ec6a016-dae5-4986-b035-c1a8cd4dc3e7@googlegroups.com>
References: <dc290806-c537-4546-b802-88dff14d81c0@googlegroups.com>
 <mailman.169.1448615930.20593.python-list@python.org>
 <f4cf8b4f-94e7-4d97-b144-65f59c20fbc1@googlegroups.com>
 <mailman.173.1448626828.20593.python-list@python.org>
 <d6c59a36-38ba-4f26-b949-18f2b226e7e3@googlegroups.com>
 <mailman.184.1448705627.20593.python-list@python.org>
 <3ec6a016-dae5-4986-b035-c1a8cd4dc3e7@googlegroups.com>
Message-ID: <1450e163-23f7-47b7-8e8d-40d304ea003f@googlegroups.com>

jf... at ms4.hinet.net at 2015/11/29  UTC+8 10:55:28AM wrote?
> > >     .....
> > >     .....
> > >     #do the rest
> > >     var_status.set('Download...')
> > >     _thread.start_new_thread(td_download, ())  #must use threading
> > > 
> > > def td_download():
> > >     result = mydll.SayHello()
> > >     if result:
> > >         var_status.set("Download Fail at %s" % hex(result))
> > >         showerror('Romter', 'Download Fail')
> > >     else:
> > >         var_status.set('Download OK')
> > >         showinfo('Romter', 'Download OK')
> > 
> > As td_download() runs in the other thread the var_status.set() methods are 
> > problematic.
> 
> No idea what kind of problem it will encounter. Can you explain?

It might be not a good idea to update GUI in a spawned thread, according to Mark Lutz's book "Programming Python", section "Using Threads with tkinter GUIs"

"If you do use threads in tkinter programs, however, you need to remember that only the main thread (the one that built the GUI and started the mainloop) should generally make GUI calls. At the least, multiple threads should not attempt to update the GUI at the same time..." 
 
> > Another complication that inevitably comes with concurrency: what if the 
> > user triggers another download while one download is already running? If you 
> > don't keep track of all downloads the message will already switch to 
> > "Download OK" while one download is still running.
> 
> Hummm...this thought never comes to my mind. After take a quick test I found, you are right, a second "download" was triggered immediately. That's a shock to me. I suppose the same event shouldn't be triggered again, or at least not triggered immediately, before its previous handler was completed. ...I will take a check later on Borland C++ builder to see how it reacts!
> 
> Anyway to prevent this happens? if Python didn't take care it for us.

then don't use thread if you prefer the GUI freeze.



From python at lucidity.plus.com  Mon Nov 30 20:26:11 2015
From: python at lucidity.plus.com (Erik)
Date: Tue, 1 Dec 2015 01:26:11 +0000
Subject: I can't understand re.sub
In-Reply-To: <lf54mg3eupq.fsf@ling.helsinki.fi>
References: <af27abe4-f81e-4d44-a504-c58d9e71986a@googlegroups.com>
 <mailman.26.1448872519.14615.python-list@python.org>
 <lf54mg3eupq.fsf@ling.helsinki.fi>
Message-ID: <565CF733.7040004@lucidity.plus.com>

On 30/11/15 08:51, Jussi Piitulainen wrote:
> Surely the straight thing to say is:
>
>     >>> foo.replace(' CONTENT_PATH ', ' Substitute ')
>     'foo bar baz spam Substitute bar spam'

Not quite the same thing (but yes, with a third argument of 1, it would be).

> But there was no guarantee of spaces around the target.

I know. It was just an example to show that there might be an option 
that's not a regex for the specific use indicated. It's up to the OP to 
decide whether they think the spaces (or any other, or no, delimiter) 
would actually be required or useful. Or whether they really prefer a 
regex after all.

> If you wish to,
> say, replace "spam" in your foo with "REDACTED" but leave it intact in
> "May the spammer be prosecuted", a regex might be attractive after all.

But that's not what the OP said they wanted to do. They said everything 
was very fixed - they did not want a general purpose human language text 
processing solution ... ;)

E.


From rxjwg98 at gmail.com  Mon Nov 30 21:14:22 2015
From: rxjwg98 at gmail.com (fl)
Date: Mon, 30 Nov 2015 18:14:22 -0800 (PST)
Subject: Could you explain this rebinding (or some other action) on "nums
 = nums"?
In-Reply-To: <mailman.37.1435191416.3674.python-list@python.org>
References: <94c2e42e-1e5f-40cf-9259-26035e277bf3@googlegroups.com>
 <mailman.37.1435191416.3674.python-list@python.org>
Message-ID: <b48d4b38-a28a-4408-8271-f79e850f453f@googlegroups.com>

On Wednesday, June 24, 2015 at 8:17:08 PM UTC-4, Chris Angelico wrote:
> On Thu, Jun 25, 2015 at 9:52 AM, fl <rxjgmail.com> wrote:
> > The reason is that list implements __iadd__ like this (except in C, not Python):
> >
> > class List:
> >     def __iadd__(self, other):
> >         self.extend(other)
> >         return self
> > When you execute "nums += more", you're getting the same effect as:
> >
> > nums = nums.__iadd__(more)
> > which, because of the implementation of __iadd__, acts like this:
> >
> > nums.extend(more)
> > nums = nums
> > So there is a rebinding operation here, but first, there's a mutating operation, and the rebinding operation is a no-op.
> 
> It's not a complete no-op, as can be demonstrated if you use something
> other than a simple name:
> 
> >>> tup = ("spam", [1, 2, 3], "ham")
> >>> tup[1]
> [1, 2, 3]
> >>> tup[1].extend([4,5])
> >>> tup[1] = tup[1]
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: 'tuple' object does not support item assignment
> >>> tup
> ('spam', [1, 2, 3, 4, 5], 'ham')
> >>> tup[1] += [6,7]
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: 'tuple' object does not support item assignment
> >>> tup
> ('spam', [1, 2, 3, 4, 5, 6, 7], 'ham')
> 
> The reason for the rebinding is that += can do two completely
> different things: with mutable objects, like lists, it changes them in
> place, but with immutables, it returns a new one:
> 
> >>> msg = "Hello"
> >>> msg += ", world!"
> >>> msg
> 'Hello, world!'
> 
> This didn't change the string "Hello", because you can't do that.
> Instead, it rebound msg to "Hello, world!". For consistency, the +=
> operator will *always* rebind, but in situations where that's not
> necessary, it rebinds to the exact same object.
> 
> Does that answer the question?
> 
> ChrisA

I have revisit the past post. In the example code snippet:

type(tup[1])
Out[162]: list

'list' is mutable. Why does the following line have errors?
In practical Python code, error is not acceptable. Then, what purpose is
for the following code here to show?

Thanks,


>>> tup[1] += [6,7] 
Traceback (most recent call last): 
  File "<stdin>", line 1, in <module> 
TypeError: 'tuple' object does not support item assignment 


From python at mrabarnett.plus.com  Mon Nov 30 22:32:31 2015
From: python at mrabarnett.plus.com (MRAB)
Date: Tue, 1 Dec 2015 03:32:31 +0000
Subject: Could you explain this rebinding (or some other action) on "nums
 = nums"?
In-Reply-To: <b48d4b38-a28a-4408-8271-f79e850f453f@googlegroups.com>
References: <94c2e42e-1e5f-40cf-9259-26035e277bf3@googlegroups.com>
 <mailman.37.1435191416.3674.python-list@python.org>
 <b48d4b38-a28a-4408-8271-f79e850f453f@googlegroups.com>
Message-ID: <565D14CE.30708@mrabarnett.plus.com>

On 2015-12-01 02:14, fl wrote:
> On Wednesday, June 24, 2015 at 8:17:08 PM UTC-4, Chris Angelico wrote:
>> On Thu, Jun 25, 2015 at 9:52 AM, fl <rxjgmail.com> wrote:
>> > The reason is that list implements __iadd__ like this (except in C, not Python):
>> >
>> > class List:
>> >     def __iadd__(self, other):
>> >         self.extend(other)
>> >         return self
>> > When you execute "nums += more", you're getting the same effect as:
>> >
>> > nums = nums.__iadd__(more)
>> > which, because of the implementation of __iadd__, acts like this:
>> >
>> > nums.extend(more)
>> > nums = nums
>> > So there is a rebinding operation here, but first, there's a mutating operation, and the rebinding operation is a no-op.
>>
>> It's not a complete no-op, as can be demonstrated if you use something
>> other than a simple name:
>>
>> >>> tup = ("spam", [1, 2, 3], "ham")
>> >>> tup[1]
>> [1, 2, 3]
>> >>> tup[1].extend([4,5])
>> >>> tup[1] = tup[1]
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>> TypeError: 'tuple' object does not support item assignment
>> >>> tup
>> ('spam', [1, 2, 3, 4, 5], 'ham')
>> >>> tup[1] += [6,7]
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>> TypeError: 'tuple' object does not support item assignment
>> >>> tup
>> ('spam', [1, 2, 3, 4, 5, 6, 7], 'ham')
>>
>> The reason for the rebinding is that += can do two completely
>> different things: with mutable objects, like lists, it changes them in
>> place, but with immutables, it returns a new one:
>>
>> >>> msg = "Hello"
>> >>> msg += ", world!"
>> >>> msg
>> 'Hello, world!'
>>
>> This didn't change the string "Hello", because you can't do that.
>> Instead, it rebound msg to "Hello, world!". For consistency, the +=
>> operator will *always* rebind, but in situations where that's not
>> necessary, it rebinds to the exact same object.
>>
>> Does that answer the question?
>>
>> ChrisA
>
> I have revisit the past post. In the example code snippet:
>
> type(tup[1])
> Out[162]: list
>
> 'list' is mutable. Why does the following line have errors?
> In practical Python code, error is not acceptable. Then, what purpose is
> for the following code here to show?
>
> Thanks,
>
>
>>>> tup[1] += [6,7]
> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
> TypeError: 'tuple' object does not support item assignment
>
When you write:

     x += y

Python tries to do:

     x = x.__iadd__(y)

If x doesn't have the "__iadd__" method, Python then tries to do:

     x = x.__add__(y)

The "__iadd__" method should mutate the object in-place and then return
itself.

Here's an example where it returns something else instead:

# Example

class Test:
     def __init__(self):
         self.string = ''

     def __iadd__(self, other):
         self.string += other
         return "Surprise!"

t = Test()
t += 'foo'
print(t)

# End of example

In the case of:

     tup[1] += [6, 7]

what it's trying to do is:

     tup[1] = tup[1].__iadd__([6, 7])

tup[1] refers to a list, and the __iadd__ method _does_ mutate it, but
then Python tries to put the result that the method returns into
tup[1]. That fails because tup itself is a tuple, which is immutable.



From josef.pktd at gmail.com  Mon Nov 30 22:45:42 2015
From: josef.pktd at gmail.com (Josef Pktd)
Date: Mon, 30 Nov 2015 19:45:42 -0800 (PST)
Subject: Is vars() the most useless Python built-in ever?
In-Reply-To: <565cf141$0$1612$c3e8da3$5496439d@news.astraweb.com>
References: <565cf141$0$1612$c3e8da3$5496439d@news.astraweb.com>
Message-ID: <98d1c37d-0c25-45fd-a06f-244eca5e3f6a@googlegroups.com>

On Monday, November 30, 2015 at 8:01:14 PM UTC-5, Steven D'Aprano wrote:
> I'm trying to understand why vars() exists. Does anyone use it?
> 
> Every time I try to use it, I find it doesn't quite do what I want. And even
> if it did, there are more obvious and/or correct alternatives.
> 
> For instance, I want to check whether a particular name is an instance
> attribute. So first I write:
> 
> "name" in obj.__dict__
> 
> but when I see the dunder name I think that's an implementation detail. And
> sure enough, not all instances have a __dict__ (e.g. if it uses __slots__
> instead) and so I re-write it as:
> 
> "name" in vars(obj)
> 
> but that also fails if obj has no instance __dict__.
> 
> But why am I looking just in the instance __dict__? Chances are I should be
> looking for the attribute *anywhere* in the instance/class/superclass
> hierarchy: 
> 
> hasattr(obj, "name")
> 
> Or, if you are worried about triggering dynamic attributes using
> __getattr__, you can do this:
> 
> sentinel = object()
> inspect.getattr_static(obj, "name", sentinel) is not sentinel
> 
> which only checks for pre-existing attributes without triggering
> __getattr__, __getattribute__, or the descriptor protocol.
> 
> 
> Either way, vars() doesn't solve the problem. What problem does it solve?

I'm using dir and vars pretty often when I'm trying to figure out new code or review a pull request, or when I'm reviewing code that I don't remember.

Both are convenient for quickly checking which attributes are available at the moment. I never realized that there might be issues with "fancy" problems. 

`vars` is convenient, for example, to check which attributes have been initialized to None, and which already have assigned values. And checking again after some calculations, I roughly see which attributes have been added or changed in the mean time.

aside: I'm boring and like code that has no magic, especially if I have to maintain it.

Josef

> 
> 
> 
> -- 
> Steven



From matthew.herzog at gmail.com  Mon Nov 30 23:54:24 2015
From: matthew.herzog at gmail.com (Mr Zaug)
Date: Mon, 30 Nov 2015 20:54:24 -0800 (PST)
Subject: Generate config file from template using Python search and
 replace.
In-Reply-To: <mailman.33.1448874871.14615.python-list@python.org>
References: <73046000-f634-40f2-9c83-f03a5db134e6@googlegroups.com>
 <mailman.3.1448752087.14615.python-list@python.org>
 <4f923003-4f85-4a69-bfda-165194211bb4@googlegroups.com>
 <mailman.11.1448837430.14615.python-list@python.org>
 <0dd0db34-7f8f-4e8b-ad6a-c82ad19c2e5e@googlegroups.com>
 <mailman.33.1448874871.14615.python-list@python.org>
Message-ID: <8c787187-910c-40df-9235-9e4c2dafb19c@googlegroups.com>

On Monday, November 30, 2015 at 4:14:48 AM UTC-5, Peter Otten wrote:
> Mr Zaug wrote:
> 
> > On Sunday, November 29, 2015 at 5:50:51 PM UTC-5, Peter Otten wrote:
> >> Mr Zaug wrote:
> >> 
> >> > When I run this script on OS X El Capitan, I see,
> >> >   
> >> >   # permission sensitive cache
> >> >   $include "_dispatcher_shared_auth-checker:
> >> > 
> >> > Was I supposed to incorporate it into the script I posted?
> >> 
> >> Are you referring to my post? I'm sorry, I can't make sense of your
> >> question.
> > 
> > Yes. The snippet you posted went way over my head. When I ran it, it
> > printed
> > 
> > # permission sensitive cache
> >   $include "_dispatcher_shared_auth-checker:
> 
> It's hard to tell from that problem description what might have gone wrong. 
> However:
> 
> In your template file you have to enclose all words you want to replace in 
> braces ("you have foo options" becomes "you have {foo} options"), to replace 
> all literal { with {{ and all literal } with }}.
> 
> Did you do that?

Yup, I sure did. So here is my current script. The only remaining task now is figuring out how to write the contents to a new file.

#!/usr/bin/env python
import os
import sys

script, template_file = sys.argv
print "Opening the template file..."

print "What is the serial number of the site?",
nnn = raw_input()

print "What is the brand, or product name?",
brand = raw_input()

print "What is the (fqdn) ServerName?",
server_name = raw_input()

print "What is the content path?",
content_path = raw_input()

print "What is the DAM path?",
dampath = raw_input()

print "Which environment is this for?",
env = raw_input()

print "What is the cache document root?",
cache_docroot = raw_input()

with open (template_file, "r") as a_string:
    data=a_string.read().replace('{SERVER_NAME}', server_name).replace('{BRAND}', brand).replace('{CONTENT_PATH}', content_path).replace('{DAMPATH}', dampath).replace('{ENV}', env).replace('{CACHE_DOCROOT}', cache_docroot)